Author Topic: solar panel installation  (Read 59086 times)

sol

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solar panel installation
« on: June 28, 2014, 09:40:26 PM »
Since it recently came up in this other thread, I thought I'd detail our solar panel installation in Washington State.  NWEdible has a very similar cost breakdown posted over at her blog, and hers is already up and running.

The summary is that we're installing twenty eight 270 watt panels on our south-facing roof, at a cost of $32,400 up front, to replace an estimated 75% of our home energy usage.  (edit 2015: turns out they replace more than 100% of our home energy use.)  This system should more than pay for itself before 2020, after which we will essentially be getting free energy (edit 2019: it paid for itself in August of 2018, after four years of operation).

The Equipment:
In order to get the Washington State production incentives of 54 cents/kWh produced, we have to use all made-in-Washington components.   The 28 panels are each about 40x65 inches and produce 270 watts, or 275 watts if I wanted to wait an additional month to get the newer panels.  We're using two Eltek THEIA string inverters to convert DC to AC for the house.  Our circuit breaker is already rated for 220 amps and it has plenty of unused slots, so we won't have to pay for any additional house wiring.  Included in our total cost is about $500 for permitting and inspection fees, and the installation of a production meter from our local utility company that will measure how much power we generate, which is used to determine how much to pay us for having solar panels through our net metering agreement.  The total system size should be 7560 kW, and in this part of the world that size of an array should produce about 1:1 on an annual basis.  So we should generate about 7500 kWh of power over the course of the year, most of which will be May through September with only about 3% of the yearly total in December.  At more southerly latitudes, the seasonal variation is less pronounced.

The Installation:
One of the reasons we bought the house was the unobstructed view of the south-facing roof.  Our 28 panels will go in a 4x7 grid, wired together and sent through the roof into our crawlspace/attic, across the house, out one of the birdholes on the side of the house above the garage and straight down to the production meter.  The inverters will be on the interior of the garage on the same wall, behind the power meter.  The panels will take up most of our available roof space, and be mounted flush to the roof on 4 inch standoffs that allow installation over top of shower fan vents and the sewer vent stacks that would otherwise be in the way.  Normally they want you to hose the panels down twice a year, but our roof is higher than all surrounding trees so I expect less maintenance than usual.

The Financial Payback:
The federal tax credit is good until Dec31 2016 and offers a 30% tax credit.  That means we'll get an extra $9720 back on our taxes next April.
If the system produces the expected amount of power, we expect our utility company to cut us a check for about $4200/year every July for the next six years.
Our local production then offsets our local consumption of power, so we buy less power from the power company.  Electricity is only about 8 cents/kWh in this part of the country, so unless you're a real power hog this isn't a major component of the payback, about $50/month.

Add those numbers up and we're expecting about $38520 in payments between now and July 2020 for our $32400 in up front cost.  In my mind, this works out to locking in a return of about 3% per year on $32.4k for the next six years, in exchange for getting most of our power for free after that.  The math is a bit more complicated than that because almost half of that cost comes back to me within a year.

Paying for the system was a complicated mixture of using a 0%-for-9-months credit card with 1% cash back and selling some investments from our taxable account in a way that tried to minimize our capital gains taxes.  We've also turned our W-2 withholding down to $0 for the remainder of the tax year in anticipation of that $9720 tax credit.  I see no point in letting Uncle Sam hold all that money for me.

One Wrinkle
We live in a development with an HOA.  I had to fill out a form notifying the architectural committee of my intentions to install solar panels.  I gave them a schematic drawing of the proposed array and a copy of the state law that makes it illegal for an HOA to prevent a homeowner from doing something that both the state and the federal government are trying to incentivize.   We'll see if they try to protest.

I'll update thread with details as the system is installed, permitted, turned on, and starts paying me.

« Last Edit: March 01, 2019, 09:16:41 AM by sol »

Zombie Burger

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Re: solar panel installation
« Reply #1 on: June 28, 2014, 10:03:18 PM »
That is pretty awesome! I can't wait to hear how this works out. 

Rural

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Re: solar panel installation
« Reply #2 on: June 29, 2014, 03:03:48 AM »
Very cool. I'm excited for you, and my turn is coming...

TomTX

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Re: solar panel installation
« Reply #3 on: June 29, 2014, 06:19:25 AM »
I'm actually very surprised at how short the payback period is.  This is awesome.  Six years is nothing. 

What's the expected life of the panels?   And what costs are you expecting for maintenance and upkeep?

State incentives will do that.

One caveat: I believe the federal solar tax credit is NON refundable. It will take your taxes to zero, but won't result in Uncle Sam cutting you a check. If we do this, we plan to look at doing a Traditional-> Roth conversion

Phy to FI

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Re: solar panel installation
« Reply #4 on: June 29, 2014, 07:00:01 AM »
This is really cool. Thanks for all the details.

teen persuasion

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Re: solar panel installation
« Reply #5 on: June 29, 2014, 08:05:12 AM »
I'm actually very surprised at how short the payback period is.  This is awesome.  Six years is nothing. 

What's the expected life of the panels?   And what costs are you expecting for maintenance and upkeep?

State incentives will do that.

One caveat: I believe the federal solar tax credit is NON refundable. It will take your taxes to zero, but won't result in Uncle Sam cutting you a check. If we do this, we plan to look at doing a Traditional-> Roth conversion

The non refundable credits is the reason we have not done this.  Low income families that owe no income tax to fed or state effectively cannot take advantage of the credits.

sol

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Re: solar panel installation
« Reply #6 on: June 29, 2014, 08:30:38 AM »
The tax credit can be carried over to multipe years if you can't use it all this year, so even lower income folks can benefit.  If you're low enough income to never pay any taxes at all then the credit would be wasted.

Expected lifetime is decades. Panels are warrantied for 25 years but there are panels built in the 70s still going strong.  It's not like they have any moving parts, so as long as you don't throw rocks at them they should be fine.  The inverters are also all solid state and apparently they fail under warranty in the first month or not at all.

Maintenance and upkeep should be negligible since we have no nearby trees to shed on them.  I'll hose them off when I clean my gutters annually, sooner if I see the performance dropping.

sol

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Re: solar panel installation
« Reply #7 on: July 25, 2014, 06:28:36 PM »
Our solar panels went up today.

Installation took 2 days and went exactly as described above.  28 panels for a total of 7560 watts. 

My power meter is currently running backwards, generating approximately $20/day in free money for the month of August.

Pictures attached are our roof before, during, and after the installation.
« Last Edit: July 25, 2014, 06:46:25 PM by sol »

dragoncar

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Re: solar panel installation
« Reply #8 on: July 25, 2014, 07:32:32 PM »
Sweet... so they rerouted the thingamajiggers (technical term) coming out of the roof?  Like the vent pipes and you lost the skylights?

I haven't even moved into my new house yet, but I'm considering solar.  California doesn't have incentives as sweet as yours, but I think the payback period is still pretty darn good.  But we'd likely have to go w/ net metering and thus would not want to oversize the system.  So my question is this:  Should I wait a whole year to determine our annual electricity usage in order to size the panel?  Or just go by a few months of data?  Any thoughts?

I also plan to have some skylights installed, and would probably want to do both projects at the same/similar time.  Would that make sense?

sol

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Re: solar panel installation
« Reply #9 on: July 25, 2014, 07:40:45 PM »
Sweet... so they rerouted the thingamajiggers (technical term) coming out of the roof?  Like the vent pipes and you lost the skylights?

We didn't have any skylights to lose.  The vent pipes are just for burping your plumbing when you flush so you don't get sewer gas backup, and thus they only need to be open to the atmosphere.  They were shortened, and are still there under the panels.  The square things near the roof ridge are attic vents, they didn't move at all.  The panels go right over them.

They put one new hole in our roof to route the power cable into and across our attic, out a bird hole, and down the far side of the house to the inverters and meters.

We are going to put in a solatube over our main staircase, but those things are pretty flexible.  It will just come out on a different roof surface.

Quote
Should I wait a whole year to determine our annual electricity usage in order to size the panel?  Or just go by a few months of data?  Any thoughts?

Our power company provides a whole year of records online.  We sized this system based on our summertime power consumption at our old house, because that house had some electric heating that this house doesn't.  When our first bimonthly power bill at the new house came in at 867kWh for our family of five, I thought maybe we had installed too many panels.  But then I realized our winter consumption is going to be way higher because we don't really use lights in the summer, and the furnace blower isn't on.  And we'll get an electric car in a year or two, so that will use up a bunch of our solar production.  And even if we don't use it on site, the power company still pays us for whatever we produce and it gets used by our immediate neighbors instead.  Net metering solves all problems.

Quote
I also plan to have some skylights installed, and would probably want to do both projects at the same/similar time.  Would that make sense?

Unless the skylights and the solar panels are going to compete for roof space, I don't think it matters.  The condition of your roof matters, though.  If the roof is going to need to be replaced in the next five or ten years, I'd consider doing that first.
« Last Edit: July 25, 2014, 07:43:55 PM by sol »

Roland of Gilead

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Re: solar panel installation
« Reply #10 on: July 25, 2014, 07:56:39 PM »
Very nice.   We have four of those same 270 watt panels that we are going to install on our truck camper.  No tax credit but generating electricity with a gasoline generator is $$$.

dragoncar

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Re: solar panel installation
« Reply #11 on: July 25, 2014, 08:07:05 PM »
We sized this system based on our summertime power consumption at our old house, because that house had some electric heating that this house doesn't.
...
Unless the skylights and the solar panels are going to compete for roof space, I don't think it matters.  The condition of your roof matters, though.  If the roof is going to need to be replaced in the next five or ten years, I'd consider doing that first.

Yeah, I'm now wondering how solar power compares to a gas furnace, and whether it would make sense to oversize and use any extra to do some resistive heating during winter (for example, a space heater just in the master bedroom, and lowering the thermostat for the rest of the house).

Unfortunately, the skylights and solar panels both want to be on my south facing slope.  But I have potential shadow sources, so it's not clear cut if that's the best option.  I'll have to observe....

edit: or run a hot tub off electric vs. a more expensive to install gas option, electric car in the future, etc. etc.  For all I know, I have plenty of space for both, it all really comes down to the details.
« Last Edit: July 25, 2014, 08:08:40 PM by dragoncar »

monarda

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Re: solar panel installation
« Reply #12 on: July 25, 2014, 10:29:17 PM »
Congrats, sol!

We have a much smaller system on one of our rentals, 8 panels for 1920 watts, installed in 2012. We'll add 9 more panels someday, but not for a couple of years.  We have Enphase microinverters on our system.  I know there are several different options for inverters,  (string inverters?). I know that microinverters can get expensive for large systems.  I'm curious about the options your installer presented to you.

dragoncar, skylights work really well on north-facing slopes. Don't rule that out...

dragoncar

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Re: solar panel installation
« Reply #13 on: July 25, 2014, 10:41:03 PM »
dragoncar, skylights work really well on north-facing slopes. Don't rule that out...

Sorry sol, I never met a thread I wouldn't hijack. 

Thanks for the note, monarda.  Didn't even think about that, although the north slope already has a skylight and that area gets enough light.  But maybe there's a way to build/paint the light wells on the north slope so that it gets reflected back down to the south side, which is pretty dark.  Or, more likely, there's enough room anyways.  I'm sure later on I'll post pictures and solicit contractor recommendations for the bay area.  There's a lot to learn about frugal home ownership.

Thegoblinchief

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Re: solar panel installation
« Reply #14 on: July 26, 2014, 07:33:47 PM »
Very cool. Wondering what the payback will look like in 5-10 years when we're on house number two. Too much uncertainty right now about how long we are staying here to put panels on this house.

Lizzy B.

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Re: solar panel installation
« Reply #15 on: October 08, 2014, 01:04:12 PM »
I know I'm bringing this thread back from the dead, but thanks very much for all these details. We're in the process of weighing our options and running the numbers on a solar instal and this breakdown was very helpful, even though we're in a different state with different incentives.

Now that you've lived with the system for a few months, what do you think of it? Any surprises?

sol

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Re: solar panel installation
« Reply #16 on: October 12, 2014, 01:25:23 PM »
Now that you've lived with the system for a few months, what do you think of it? Any surprises?

Living with solar panels has become very mundane.  They just work.  There is no maintenance, no hassle, no problems.  At least not yet.  It's just like having regular electricity, except that now I can sit on my deck drinking a beer that has been cooled by the sun.

They've been running for 72 days and have generated approximately 2700 kWh of power, a bit more than I was expecting based on my initial calculations.  Multiplied by the $0.54/kWh production incentive rate, I've already earned almost $1500.  About $20/day average even as the days have been getting shorter.

Our first power bill came in a while back.  We get billed every two months, and we had our panels up and running for about six weeks of the billing period for a net surplus of 1402 kWh produced in excess of what we used.  Our semi-monthly power bill went from $83 to -$103 dollars after the $11 "customer connection charge" is included.

The $103 credit on our bill was applied against our water bill, lowering our total bill even further.  Not quite to zero, though. 

The real question will be what happens with the costs next year.   Our early tax forms suggest we should qualify for $9720 in tax rebate next April and I'm expecting about $4200 in incentive payment from the utility next July/August.  I'll report back when we get there.


« Last Edit: October 12, 2014, 01:30:52 PM by sol »

TomTX

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Re: solar panel installation
« Reply #17 on: October 12, 2014, 03:07:23 PM »
Washington has some really impressive incentives.

hwstar

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Re: solar panel installation
« Reply #18 on: October 12, 2014, 06:33:57 PM »
I've got a small 1kW battery backup/UPS system not connected to the grid I designed and installed myself just to see what was involved in self-installation. It powers my computers and electronics in the house on a dedicated circuit.

The biggest risk was is getting the brackets for the panels installed into the rafters. It requires precise measuring skills.

I think that having a system installed by a professional almost triples the total system cost. There are lots of contractors on my area running full page ads in the newspapers. To cover the cost of running those ads, you know they are charging way more than necessary.

Looking on the web, I see 3kW grid tie Enphase kits selling for $6.5k. If you are electrically and mechanically inclined, I would check out what is being offered,
but make sure you don't have issues with insurance or permits before purchasing a system.


sol

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Re: solar panel installation
« Reply #19 on: February 18, 2015, 08:51:41 PM »
An update on our solar panels as winter draws to a close...

My 7560W of rooftop solar panels have produced about 4300 kWh of electricity since going live July 30.  That's 6.5 months through the dark northwest winter. 

The insolation maps predict that the 7 months of August through February should produce 43% of our annual energy.  Doing the math on what my system has produced, I expect our 7500W are going to produce close to 10,000 kWh in the first year, which at 54 cents/kWh produced means we're going to exceed the $5000/year maximum state production incentive payment. 

I'm not really complaining about leaving money on the table.  In fact I'm thrilled they're producing so much more than expected.  Maybe because it's been such an unusually sunny and dry winter?

If my math holds up, this higher-than-expected production value means that by the time our incentive payments stop in 2020 we will have collected $30k in payments plus $8800 in reduced power costs for an effective rate of return of 3.7 percent (on my $32.4k outlay) over six years instead of the 2.95% I was previously expecting.  I'm thinking of this like buying a 3.7% tax free bond with a six year duration, and in exchange I get free power for the remaining life of my system.  Which I'm hoping is 20+years.

A second side effect of this new higher production is that combined with some efficiency improvements, I'm pretty sure my house is going to end up with a net negative electricity consumption for the year.  Do I get a sticker?
« Last Edit: February 18, 2015, 09:04:31 PM by sol »

gimp

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Re: solar panel installation
« Reply #20 on: February 18, 2015, 11:39:31 PM »
Yeah you get a fucking sticker. Awesome.

The EE in me wonders about future wiring for houses - quite a lot of our devices operate on DC power, solar panels generate DC power, but it gets converted to AC and back since all our sockets, wiring, fuses, etc etc, operates on AC. I wonder if in the future we'll have an amount of pure DC sockets, with simple compatibility for simple devices (like heating elements). For example, if a house has an electric heating system, building it to operate on AC or DC would be a major efficiency boost since it's one of the biggest electric costs. Ditto boiler / water heater, oven, fridge - the big expensive energy-slurping devices. Bit more up-front expense on designing the proper home electrical system, and the proper dual-type electrical devices, but hopefully over the long term it would be worth it with efficiency gains.

I also think we will shortly need to rethink the way we bill power - there should be two line items: fixed costs for grid maintenance, expansion, and operation; and variable costs for energy usage. Some places already do this, but some will need to. No matter how much power we generate with solar panels, we still have to pay for the grid! (Especially since time-variable power sources like wind and solar require a somewhat different approach to storage and on-demand generation.)

Anyways, cool stuff. The more we can generate off rooftop power, the less we have to rely on single sources of power. The more we buy, the cheaper it gets. I'm looking forward to control microprocessors embedded into each solar cell on each solar panel.

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Re: solar panel installation
« Reply #21 on: February 19, 2015, 12:40:31 AM »
Thanks for all the detailed information Sol.  I plan to install solar in the distant future, so it was interesting to read your experience. 

What's awesome is that solar technology has a lot of room for improvement, so we'll be able to generate even more power in smaller spaces each few years.

Roland of Gilead

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Re: solar panel installation
« Reply #22 on: February 19, 2015, 06:25:12 AM »
$0.54 per Kwh?   We pay about $0.10 per Kwh for our electricity in the NW.


At $0.54 per Kwh I could make money by running a gasoline generator using $2 a gallon gas (get about 10kwh out of a gallon)

A 10kw generator running for an hour would cost $2 and generate a profit of $3.40.

1000 hours = $3400.


Hmmm...

brooklynguy

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Re: solar panel installation
« Reply #23 on: February 19, 2015, 06:45:50 AM »
I'm thinking of this like buying a 3.7% tax free bond with a six year duration, and in exchange I get free power for the remaining life of my system.

What about the market value of the solar panel system itself?  Does it materially enhance the value of your home (or perhaps detract from it)?

What's awesome is that solar technology has a lot of room for improvement, so we'll be able to generate even more power in smaller spaces each few years.

How quickly is solar panel technology expected to advance?  If this technology is going to follow the path of the personal computer and allow a pocket-sized panel to power a city in the near future, I wouldn't want to be an early adopter stuck with today's lumbering panels on my roof.  It was an easier decision for sol because WA's generous incentives speed up the breakeven point, but the last time I looked into the possibility of solar power the math didn't work out in my favor.  And my initial layman's assessment was that my small roof doesn't have sufficient space for the panels between the skylights and other obstructions.  Also, the possibility of installing solar panels competes in my mind with the possibility of installing a living green roof, unless it is possible for those two systems to coexist on my roof.

Thegoblinchief

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Re: solar panel installation
« Reply #24 on: February 19, 2015, 06:46:52 AM »
$0.54 per Kwh?   We pay about $0.10 per Kwh for our electricity in the NW.


At $0.54 per Kwh I could make money by running a gasoline generator using $2 a gallon gas (get about 10kwh out of a gallon)

A 10kw generator running for an hour would cost $2 and generate a profit of $3.40.

1000 hours = $3400.


Hmmm...

The $0.54 rate is the inflated reimbursement rate because it's renewable electricity.

dragoncar

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Re: solar panel installation
« Reply #25 on: February 19, 2015, 11:29:46 AM »
I'm thinking of this like buying a 3.7% tax free bond with a six year duration, and in exchange I get free power for the remaining life of my system.

What about the market value of the solar panel system itself?  Does it materially enhance the value of your home (or perhaps detract from it)?

What's awesome is that solar technology has a lot of room for improvement, so we'll be able to generate even more power in smaller spaces each few years.

How quickly is solar panel technology expected to advance?  If this technology is going to follow the path of the personal computer and allow a pocket-sized panel to power a city in the near future, I wouldn't want to be an early adopter stuck with today's lumbering panels on my roof.  It was an easier decision for sol because WA's generous incentives speed up the breakeven point, but the last time I looked into the possibility of solar power the math didn't work out in my favor.  And my initial layman's assessment was that my small roof doesn't have sufficient space for the panels between the skylights and other obstructions.  Also, the possibility of installing solar panels competes in my mind with the possibility of installing a living green roof, unless it is possible for those two systems to coexist on my roof.

I'm with you - although solar appeals to me, I expect to reap the benefits through reduced grid prices once solar becomes cheap enough.  The only thing making it attractive now is external incentives (which aren't so hot anymore in my area).  I'll still run the numbers once a year.

gimp

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Re: solar panel installation
« Reply #26 on: February 19, 2015, 01:44:25 PM »
Quote
How quickly is solar panel technology expected to advance?  If this technology is going to follow the path of the personal computer and allow a pocket-sized panel to power a city in the near future, I wouldn't want to be an early adopter stuck with today's lumbering panels on my roof.

Computers have advanced because they benefit from moore's law - and let me belabor the point a little because so many people get this wrong.

Moore's law is an observation, that guides R&D spending for the big dogs; the observation is this: every ~2 years, give or take, the number of transistors you can place cheaply in a certain area doubles. That is, if today's chip has 1 billion transistors in 100 square millimeters, two years from now the same price buys you either 2 billion transistors, or half the silicon area (price) buys you the same 1 billion. This is only a law while it lasts, but it has lasted about 40-45 years, and will probably last a while yet - all doom and gloom predictions have thus far failed to materialize (though undoubtedly there are limits to the way we do things now, we change the way we do things as time goes on; traditional planar scaling ended at 90nm about 5 generations / ~10 years ago, but you haven't noticed.)

What does not really go down is the price of silicon itself. In fact, the price of silicon wafers only really goes down when wafers transition sizes - 8 inch to 12, or the upcoming 12 to 18. Interesting side note: each transition has knocked out about half the competition, because dealing with bigger wafers means massive expenses.

So you see, moore's law benefiting computers is economics more so than physics.

Solar panels, however, don't benefit from smaller transistors. Solar panels are silicon but the cost of silicon is... well, the cost of obtaining, purifying, growing, cutting, processing, and shipping sand, more or less.

Efficiency gains in solar panel energy production don't follow moore's law - entirely different beast. (If they did, we'd have nearly infinite energy in a couple decades, just as we now have seemingly infinite compute power compared to two decades ago.)

Advancement in solar panels is as follows, roughly speaking:

- Efficiency, small improvements, using different materials and geometries. There're black solar panels, which are far more efficient than your usual panels, but also prohibitively expensive for all but the most critical applications (space).
- Cost reduction; high volume manufacturing means cost all along the supply chain can reduce; time and money make this happen.
- Weight reduction: cutting panels thinner makes them weigh less; less material means less cost, and you also get less cost since they're easier to transport and install.
- Power conversion efficiency in surrounding systems - that is, better and cheaper inverters that last longer.
- Sun-following and weather-predicting gets more power and helps grids balance better.
- Form factors for different needs. For example, foldable flexible solar panel sheets that can be rolled up and carried in a backpack. Downside: far less power generated.
- We'll most likely start putting controllers right into the solar panel silicon - microchips embedded into each cell to improve efficiency by rerouting power around poorly-performing cells (also see solar tracking and weather prediction.)

The short of it all is this: if you put a solar panel up on the roof today, the panels in 20 years will be cheaper, lighter, smarter, but not nearly efficient enough to make your old panels useless.

dragoncar

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Re: solar panel installation
« Reply #27 on: February 19, 2015, 03:30:58 PM »
Quote
How quickly is solar panel technology expected to advance?  If this technology is going to follow the path of the personal computer and allow a pocket-sized panel to power a city in the near future, I wouldn't want to be an early adopter stuck with today's lumbering panels on my roof.

Computers have advanced because they benefit from moore's law - and let me belabor the point a little because so many people get this wrong.

Moore's law is an observation, that guides R&D spending for the big dogs; the observation is this: every ~2 years, give or take, the number of transistors you can place cheaply in a certain area doubles. That is, if today's chip has 1 billion transistors in 100 square millimeters, two years from now the same price buys you either 2 billion transistors, or half the silicon area (price) buys you the same 1 billion. This is only a law while it lasts, but it has lasted about 40-45 years, and will probably last a while yet - all doom and gloom predictions have thus far failed to materialize (though undoubtedly there are limits to the way we do things now, we change the way we do things as time goes on; traditional planar scaling ended at 90nm about 5 generations / ~10 years ago, but you haven't noticed.)

What does not really go down is the price of silicon itself. In fact, the price of silicon wafers only really goes down when wafers transition sizes - 8 inch to 12, or the upcoming 12 to 18. Interesting side note: each transition has knocked out about half the competition, because dealing with bigger wafers means massive expenses.

So you see, moore's law benefiting computers is economics more so than physics.

Solar panels, however, don't benefit from smaller transistors. Solar panels are silicon but the cost of silicon is... well, the cost of obtaining, purifying, growing, cutting, processing, and shipping sand, more or less.

Efficiency gains in solar panel energy production don't follow moore's law - entirely different beast. (If they did, we'd have nearly infinite energy in a couple decades, just as we now have seemingly infinite compute power compared to two decades ago.)

Advancement in solar panels is as follows, roughly speaking:

- Efficiency, small improvements, using different materials and geometries. There're black solar panels, which are far more efficient than your usual panels, but also prohibitively expensive for all but the most critical applications (space).
- Cost reduction; high volume manufacturing means cost all along the supply chain can reduce; time and money make this happen.
- Weight reduction: cutting panels thinner makes them weigh less; less material means less cost, and you also get less cost since they're easier to transport and install.
- Power conversion efficiency in surrounding systems - that is, better and cheaper inverters that last longer.
- Sun-following and weather-predicting gets more power and helps grids balance better.
- Form factors for different needs. For example, foldable flexible solar panel sheets that can be rolled up and carried in a backpack. Downside: far less power generated.
- We'll most likely start putting controllers right into the solar panel silicon - microchips embedded into each cell to improve efficiency by rerouting power around poorly-performing cells (also see solar tracking and weather prediction.)

The short of it all is this: if you put a solar panel up on the roof today, the panels in 20 years will be cheaper, lighter, smarter, but not nearly efficient enough to make your old panels useless.

Moore's law is actually about the number of transistors per package at which manufacturing cost is minimum.  This can (and has) meant larger total chip area, so it's not necessarily density per se.

Everyone interested should read the original paper, which is only about 3 pages of actual text.
http://www.monolithic3d.com/uploads/6/0/5/5/6055488/gordon_moore_1965_article.pdf

Sunny

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Re: solar panel installation
« Reply #28 on: February 19, 2015, 03:55:33 PM »
It was wonderful to read about your installation and success.  My installation in Illinois was completed in late August 2014.  Despite issues with ComEd installing the proper meter five months late, our production has been great.   Today's I checked at 4 pm and we had produced 45.50 KWH.   Solar around here is rare and I'm planning to start a blog as I educate myself about what a residential solar homeowner needs to know.

I am currently getting used to real-time pricing, which solar owners are encouraged to use.

Illinois offers a 25% renewable energy rebate and the 2014 awards are being held up by our new Governor Rauner. 

Just heads up too, regarding the 30% federal tax credit presently ends with the 2016 tax year.  It is impossible to say at this point If it will be renewed. 

Mrs. PoP

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Re: solar panel installation
« Reply #29 on: February 19, 2015, 05:53:22 PM »
Missed this when it was first posted, but the timing is great as our system is scheduled to begin installation next week. 

Ours will be very similar in size to Sol's, 28 panels arranged 2x14 on our south facing back roof deck with excellent exposure to the sun in S FL.  The system will be rated for ~7.56kW, but should produce over 10,000 kWh of power throughout the year, enough to power 100% of our power needs. 

Our upfront costs are ~$30K, $9K of which will be coming back to us on our 2015 federal taxes, and ~$15K of which will be coming  back to us a couple of months after we finish the installation in the form of FPL (our utility company) rebates to the tune of $2/watt that we successfully applied for in January. 

Our net out of pocket will be $6K, which equates to just about 5 years worth of energy cost based on the past couple of years worth of usage (~$100/mo average). 

I'm really excited to have them go up!  Fingers crossed the installation goes smoothly. 

gimp

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Re: solar panel installation
« Reply #30 on: February 19, 2015, 09:36:05 PM »
Quote
Moore's law is actually about the number of transistors per package at which manufacturing cost is minimum.  This can (and has) meant larger total chip area, so it's not necessarily density per se.

Splitting hairs. I have both his paper and speech hosted on my website as well. Considering that the cost of wafers hasn't changed much over the past couple generations for given requirements, having the same cost per piece of silicon almost necessitates having a very similar area. All the other factors - margin for profit, margin to pay for R&D, margin to pay for tooling and fabs - are also a different topic.

Quote
The complexity for minimum component costs has increased at a rate of roughly a factor of two per year (see graph on next page). Certainly over the short term this rate can be expected to continue, if not to increase.

Quote
The new slope might approximate a doubling every two years, rather than every year, by the end of the decade.

We can also chat about packaging costs, which people seem to forget - but between generations, they also don't change much (at least not for single chips, certainly in aggregate a 30 cent difference matters.)

Anyways. We can agree solar panels don't do these things.

sol

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Re: solar panel installation
« Reply #31 on: February 20, 2015, 06:57:58 PM »
At $0.54 per Kwh I could make money by running a gasoline generator using $2 a gallon gas (get about 10kwh out of a gallon)

Yea, that crazy 54 cent number is because Washington is trying to encourage people to install panels and inverters made in Washington by Washington companies.  If you use out-of-state equipment the incentive payments are less attractive.

So naturally the locally made equipment costs more.  It's basically a subsidy to the local companies by the state legislature, by way of intermediate consumers like me.  But those companies are smart enough to figure out what to charge so that consumers will opt to pay more for local equipment and get the higher incentive payments.

What about the market value of the solar panel system itself?  Does it materially enhance the value of your home (or perhaps detract from it)?

As a ballpark, I think the panels are worth roughly half of their retail installation cost after one year, but it doesn't matter much to me because we're not planning on selling until the panels are fully depreciated.

What's awesome is that solar technology has a lot of room for improvement, so we'll be able to generate even more power in smaller spaces each few years.

Solar panels are ultimately limited by the energy available in sunlight at your location.  They might get two or three times better over the coming century, but they won't ever get 10 times better. 

I think the biggest risk, for a homeowner looking at a solar installation, isn't that the panels will be made more efficient but that they'll be made obsolete by some other power technology that essentially solves the energy crisis.  We'll all feel pretty silly about paying $30k for residential solar panels if power costs drop to to 1 cent per kWh plus grid maintenance costs.  I don't think anyone expects that to happen in the next 20 years, but over the century timescale I think it's possible.

sol

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Re: solar panel installation
« Reply #32 on: February 20, 2015, 07:13:46 PM »
Thinking about this today has made me think I've done my math wrong because I neglected the 30% federal tax credit in the above analysis in post 19.

My up front cost was 32,400.  That money is gone, so I'm $32,400 in the hole on day one.  Over the next six years I'll collect $30,000 in incentive payments, $9720 in tax rebate, and about $800/year in reduced power bills for a six year total of $44,520.

My $32,400 initial investment would have to grow at 6.56% per year to be worth $44,520 after six years, assuming annual compounding.

And my return should actually be a little better than that, because I'm getting about a third of that total ($9720+$5000+$800) back in the first year, not at the end.  So I can reinvest it elsewhere for the remaining five years of the six year cycle.  Also power costs might go up over that six years, slightly increasing my return a bit more.

Someone check my math on this?  I feel like I'm missing something important here.  My original estimate was to expect about 3.2% return (in original post up top) based on 7560 kWh of production per year, and my new estimate is about 6.5% return based on 10,000 kWh of production. 

It amazes me that a 30% higher than expected production number has almost doubled my ROI on these solar panels, but between the 54 cents/kWh incentive and the 8.5 cents/kWh reduction in power purchased, it adds up in a hurry.  Of course, that 30% apparent increase in production is just based off of six dark months so far, so we'll have to see how it actually pans out after a full year.
« Last Edit: February 20, 2015, 07:15:41 PM by sol »

ChrisLansing

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Re: solar panel installation
« Reply #33 on: February 20, 2015, 07:45:38 PM »
Yeah you get a fucking sticker. Awesome.

The EE in me wonders about future wiring for houses - quite a lot of our devices operate on DC power, solar panels generate DC power, but it gets converted to AC and back since all our sockets, wiring, fuses, etc etc, operates on AC. I wonder if in the future we'll have an amount of pure DC sockets, with simple compatibility for simple devices (like heating elements). For example, if a house has an electric heating system, building it to operate on AC or DC would be a major efficiency boost since it's one of the biggest electric costs. Ditto boiler / water heater, oven, fridge - the big expensive energy-slurping devices. Bit more up-front expense on designing the proper home electrical system, and the proper dual-type electrical devices, but hopefully over the long term it would be worth it with efficiency gains.

I also think we will shortly need to rethink the way we bill power - there should be two line items: fixed costs for grid maintenance, expansion, and operation; and variable costs for energy usage. Some places already do this, but some will need to. No matter how much power we generate with solar panels, we still have to pay for the grid! (Especially since time-variable power sources like wind and solar require a somewhat different approach to storage and on-demand generation.)

Anyways, cool stuff. The more we can generate off rooftop power, the less we have to rely on single sources of power. The more we buy, the cheaper it gets. I'm looking forward to control microprocessors embedded into each solar cell on each solar panel.

Before rural electrification a lot of farms had wind turbines that produced DC power.   The outlets/lights were DC.    32 volts, if memory serves.   

Maybe you would know this - can LED lights work on DC?   

gimp

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Re: solar panel installation
« Reply #34 on: February 20, 2015, 08:08:22 PM »
I did not know that about rural areas using DC. Turbines / generators can be built to produce either DC or AC, without much issue (different geometries, not bulky / expensive / lossy converters.) Just how you can have DC and AC motors. 32 volts, very interesting. Good information!

LEDs work on DC. LED lights in place of lightbulbs take your AC from the socket and rectify it back into DC. Actual light bulbs don't give a shit whether it's AC or DC, they just heat a filament till it produces light regardless of how the electrons are wiggling or moving.

LEDs work on DC because LEDs - light emitting diodes - are diodes, meaning they pass current one way. (Okay, ignore breakdown voltages and zener diodes.) They are very simple devices to use.

Cool LED facts:

They're a bit of an art to make - certainly science, but a bit of an art as well, due to things like color variation.

White LEDs are actually blue. It's actually more complicated than that but that's a decent summary. A more expensive way to do it is to mix two colors (eg, blue and yellow) or three (red-green-blue). Fancy LED bulbs can have controllable color - simply grab a remote and make it more yellow, or more red, or more white, or whatever you want.

Superbright LEDs are complicated to design because they take so much power. A light bulb might be a 60W device, but it's very simple - metal contacts, glass shell, filament, no air inside. Everything is designed to deal with the heat properly, and it's a known design, and trivial now. A superbright LED that takes 3W, on the other hand, sits on a circuit board which unlike a piece of metal does not like heat nearly as much. So a 12W LED bulb might have several LEDs, which much be arranged in a careful pattern, with proper heat sinks. Not only that, but they have to be mindful that heat builds up and has nowhere to go; they don't stick fans on these things, and especially if the bulb is on the ceiling upside-down... the heat builds up. So the bulbs have the be designed very carefully to not fail due to heat in reasonable operating conditions. This was, and still is, a large reason for the high cost of LED bulbs. I can buy superbrights for a few cents each, and the rectifier and other circuitry might be a dollar in low volume... but the enclosure, and spacing, and layout, all took quite a bit of R&D to get right, and that has to be paid for. For this reason, LED bulbs get cheaper every year; I would not be surprised to see them in the $2 range within a few years at hardware stores.

ChrisLansing

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Re: solar panel installation
« Reply #35 on: February 21, 2015, 06:21:36 AM »
@ gimp   Thank you, interesting info.   

@ OP  A very inspiring thread.    I'm going to look into the incentives here in MI.     

Question, how do you repair the shingles under the panels?   Do they just get removed when the time comes to re-shingle?   Is it manageable for one or two people to remove the panels?   

A second question,  my house has a gable at the S side, could I mount panels on the S wall instead of on the roof?      I know they can be mounted that way, but I'm wondering about having the correct angle.   

brooklynguy

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Re: solar panel installation
« Reply #36 on: February 21, 2015, 06:23:11 AM »

My $32,400 initial investment would have to grow at 6.56% per year to be worth $44,520 after six years, assuming annual compounding.

...

Someone check my math on this?  I feel like I'm missing something important here.  My original estimate was to expect about 3.2% return (in original post up top) based on 7560 kWh of production per year, and my new estimate is about 6.5% return based on 10,000 kWh of production. 

If you're trying to figure out your rate of return with annual compounding, your arithmetic is off.  Your expected return using your original numbers should have been 2.93%.  Your expected return using your updated numbers is 5.44%.  However, none of this changes either of your overall points, that (i) this is a great return on investment (especially considering that, as you said, the return is actually higher because some of your return of capital is front-loaded, your energy savings may be higher than projected (but of course this could cut the other way too, if power rates go down), and you are ignoring for purposes of this calculation the almost-free energy you will be getting for the remaining life of the system after the six year period) and (ii) the higher-than-expected energy production almost doubled your return on investment. 

That said, the ROI figures you quotes are closer to the actual ROI without compounding (which are actually 3.1%, using the original numbers, and 6.2%, using the updated numbers).  For your analysis, I think it makes more sense to ignore compounding (treating your investment like a bond that pays interest annually, rather than a zero-coupon bond that compounds interest).  As stated above, by using annually compounded rate of return as your metric and ignoring the effect of the early return of capital, you are materially understating your return.  Because so much of your return of capital is front-loaded, you are correct that your true return is even higher than the nominal 6.2% figure (even if you continue to ignore the other factors identified above that make your actual return higher still).

An even better analysis would treat your investment as a bond that makes payments exactly when you will actually be receiving your payments so we don't have to ignore the effect of front-loaded payments, but I'm way too lazy to attempt to calculate ROI that way.

NaturallyHappier

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Re: solar panel installation
« Reply #37 on: February 21, 2015, 06:54:55 PM »
Great investment.   Here is a summary of my solar journey.


Initial Install                       $90,136.00
PA Grant                              -$22,500.00
Federal rebate                      -$27,014.00
Expansion                               $33,610.00
Federal rebate                      -$10,083.00
Total Out of Pocket               $64,149.00
   
Srec Sales 2010   -$2,580.00
Srec Sales 2011   -$4,070.00
Srec Sales 2012   -$4,810.00
Srec Sales 2013   -$10,070.00
Srec Sales 2014   -$10,832.50
Srec Sales 2015   $0.00
Total Srec          -$32,362.50
   
Power Saved/Income 2010   -$1,757.45
Power Saved/Income 2011   -$2,300.66
Power Saved/Income 2012   -$2,455.59
Power Saved/Income 2013   -$3,265.91
Power Saved/Income 2014   -$3,406.98
Power Saved/Income 2015   $209.73
Total Power Saved.Income   -$12,976.87
   
Remaining Payoff    $18,809.63
   
Projected Yearly Income   $14,200.00
Years left for payback            1.32462202112676
Payoff Date                           5/21/2016
« Last Edit: February 21, 2015, 06:59:00 PM by FranklinBuffett »

monarda

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Re: solar panel installation
« Reply #38 on: February 22, 2015, 10:25:47 AM »
Nice numbers, FranklinBuffett!

What's the size of your system?  It seems to be that the larger the system, the quicker the payback.

NaturallyHappier

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Re: solar panel installation
« Reply #39 on: February 22, 2015, 10:53:00 AM »
It was 11.5 KW when I initially installed it in April of 2010.  I expanded it in April of 2013 to 17.5 KW. 

I got somewhat lucky.  When I installed the system in 2010 Solar Renewable Energy Credits (SRECs) in PA were bring $325.00 per MW generated.  The market crashed and then went down to $5.00.  In 2010 PA residents could sell SRECs in Washington DC and Ohio as well as PA.  When the PA market crashed DC revised their laws to exclude out of state SRECs except if the system was registered prior to JAN 2011.  Now I sell my SRECs to DC for $480.00 each.  PA SRECs are currently only selling for $50.00 each.

I capitalized on my good luck and expanded the system in 2013, or it would be paid off already.

MrFrugalChicago

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Re: solar panel installation
« Reply #40 on: February 22, 2015, 01:25:15 PM »
I heard the solar panels lose a little bit of efficiency each year, and after 10 or so years are only making half the power.  Is this no longer true? Or do they lose power faster?

sol

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Re: solar panel installation
« Reply #41 on: February 22, 2015, 01:35:54 PM »
I heard the solar panels lose a little bit of efficiency each year, and after 10 or so years are only making half the power.  Is this no longer true? Or do they lose power faster?

Not quite that fast.  Most of the estimates for new panels are less than 1% per year, with the fastest degradation happening in places where it is sunny and hot, like Arizona.  Solar panels are more efficient and last longer in cooler temperatures.

Here in Washington we tend to get a lot of sunny but cooler days, so the panels shouldn't degrade quite so quickly.  We also benefit from regular rain to wash of the dust and grime that degrades panels in other parts of the country.

NaturallyHappier

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Re: solar panel installation
« Reply #42 on: February 22, 2015, 02:38:06 PM »
I heard the solar panels lose a little bit of efficiency each year, and after 10 or so years are only making half the power.  Is this no longer true? Or do they lose power faster?

Not quite that fast.  Most of the estimates for new panels are less than 1% per year, with the fastest degradation happening in places where it is sunny and hot, like Arizona.  Solar panels are more efficient and last longer in cooler temperatures.

Here in Washington we tend to get a lot of sunny but cooler days, so the panels shouldn't degrade quite so quickly.  We also benefit from regular rain to wash of the dust and grime that degrades panels in other parts of the country.

I have not observed any degradation of output after 5 years, but I have to admit that it would be very hard to tell because of the variability of the weather.

If I had to guess, I would say they will eventually fail like a window would fail in your home.  The seal will break between the glass and the frame and moisture will get into the panel.

I have had to replace 4 panels and an inverter because I had a lightning strike, but this was covered by my homeowners insurance.  I also replaced one panel because it blew off the racking.  This was caused by it not being installed correctly.

gimp

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Re: solar panel installation
« Reply #43 on: February 24, 2015, 02:13:35 PM »
I heard the solar panels lose a little bit of efficiency each year, and after 10 or so years are only making half the power.  Is this no longer true? Or do they lose power faster?

The entire system loses efficiency over time. Solar panels get less efficient, and also inverters, batteries, and anything else you have, gets less efficient with age as well. This is different from outright failure going from full to zero after a hailstorm or something.

The current figures are something like: 25 years should still see at least 80% of the original efficiency. Some do better. http://energyinformative.org/lifespan-solar-panels/

If you get one of those deals, like from solarcity, where someone else pays for the solar panels and takes your federal/state refund and sells you the resultant energy at a lower cost than the grid, they don't do so in perpetuity - after, for example, 20 years (depending on the contract) your business relationship is finished and you keep the panels. That means you'd estimate about 10 years of free (less maintenance if applicable) generation after 20 years of paid-for power. Generally speaking, modern panels are considered to last 30 years. I assume that they will usually last longer than that.

HelloImNotHome

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Re: solar panel installation
« Reply #44 on: March 01, 2015, 11:28:24 PM »
If anyone has questions about how SolarCity financing options work let me know. I can also send a blank copy of the contract if you wanna see the fine print. If you have questions about system size and options I know a few of the little things they don't specifically advertise to customers that can get you a lower effective rate for power depending on the plan and a few details about the home.

I work there as a PV Designer / Energy Consultant.

Also, dunno if people know this but just like Ting (the referral thread being how I found this site) SolarCity has a sweet option that gives you $250 ( you have to agree to be sent a 1099 at the end of the year) for every referral you submit to a Consultant that gets installed.

Happy to help with any questions.

HelloImNotHome

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Re: solar panel installation
« Reply #45 on: March 01, 2015, 11:35:01 PM »
Hello Gimp,

Just so you know with SolarCity if you select a plan that allows SolarCity to collect the Tax Credit then you are in effect leasing the system. If you select the lease option you are never give the option to buy the system, after 20 years you can renew for an additional 10 (keeping your same fixed rate). On a power purchase agreement (PPA) at any point past the 5 year mark or when you sell your home you may purchase the system at fair market value as determined by an independent 3rd party. In my opnion the PPA is the best option for people that are not in a tax liability position but want to own the system eventually.

Hope this helps

- Robert
SolarCity PV Designer / Energy Consultant.


I heard the solar panels lose a little bit of efficiency each year, and after 10 or so years are only making half the power.  Is this no longer true? Or do they lose power faster?

The entire system loses efficiency over time. Solar panels get less efficient, and also inverters, batteries, and anything else you have, gets less efficient with age as well. This is different from outright failure going from full to zero after a hailstorm or something.

The current figures are something like: 25 years should still see at least 80% of the original efficiency. Some do better. http://energyinformative.org/lifespan-solar-panels/

If you get one of those deals, like from solarcity, where someone else pays for the solar panels and takes your federal/state refund and sells you the resultant energy at a lower cost than the grid, they don't do so in perpetuity - after, for example, 20 years (depending on the contract) your business relationship is finished and you keep the panels. That means you'd estimate about 10 years of free (less maintenance if applicable) generation after 20 years of paid-for power. Generally speaking, modern panels are considered to last 30 years. I assume that they will usually last longer than that.

b4u2

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Re: solar panel installation
« Reply #46 on: March 27, 2015, 08:47:39 AM »
Being an electronic technician I have always wanted solar power for my house. I have just never figured out how to pay for it. I am still in debt payoff leg of reaching FI. I did build one panel myself from scratch a few years ago. It works but never had enough money to build or buy more. I see these $30k systems being installed and love the idea but just don't know how to pay for it. Iowa does not have, at least to my knowledge, a very good incentive plan for solar. The front of my house faces south with roof and would be ideal, I think, for a solar panel system. I plan on being in this house 10-15 more years but not sure if it would still be worth it for me.

gimp

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Re: solar panel installation
« Reply #47 on: March 27, 2015, 12:32:26 PM »
Good to know, solarcity guy.

b4u2, perhaps you should talk to the solarcity guy who posted right above yours.

Axecleaver

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Re: solar panel installation
« Reply #48 on: March 27, 2015, 12:47:22 PM »
Related to the discussion on Moore's law and how the price of solar panels is changing... Good article and graph here about solar panel installation prices:

http://www.pv-magazine.com/news/details/beitrag/us-installed-solar-pv-costs-continue-to-fall_100016490/#axzz3Th5jnVCr

Median installed price in 2013 was $4.70/watt. Compare to $12/watt in 1998. Prices today in my area are around $3.50/watt (under 10k watts). The ROI breakeven for us in upstate NY is about 4-5 years, due to weather (bad), being quite a ways north (bad), but high cost of electricity (gov't here is very tax-heavy).

brooklynguy

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Re: solar panel installation
« Reply #49 on: April 07, 2015, 08:19:13 AM »
Came across this yesterday and thought it sounded interesting:

http://www.gocloudsolar.com/

It's a start-up that basically allows you to purchase one or more solar panels (or a fractional interest in a single solar panel), then let the company install and maintain your panel(s) in their solar farm and, on your behalf, sell the electricity generated by your panel(s).

A single full panel costs $750, and CloudSolar estimates that the total economic output over a 25-year period is $2,250 (of which CloudSolar will take a 20% cut for their services).  But the website's disclosure is woefully inadequate regarding the details of this estimate.

The website makes a half-hearted attempt to couch this whole enterprise in non-investment terms ("we're selling solar panels and related services, not an investment vehicle")--no doubt primarily to avoid securities law issues--but it's interesting to compare the expected return to what an individual homeowner can expect to achieve.  The stated expected return (which, according to the website's FAQ, seems to include anticipated government tax credits and incentives) falls short of sol's anticipated return (as outlined earlier in this thread), even before reduction for the company's 20% fee.  But it might compare more favorably with the economic performance of a solar system for an individual residing outside Washington State with less generous incentive programs.