Author Topic: solar panel installation  (Read 65363 times)

sol

  • Walrus Stache
  • *******
  • Posts: 8465
  • Age: 45
  • Location: Pacific Northwest
Re: solar panel installation
« Reply #200 on: August 29, 2018, 06:01:28 PM »
I did do a net present value calculation on my expected future payments, when I was first buying the solar panels, and decided the discounted repayments were worth about 3.2% per year.  At this point, I have no idea if that analysis is still anywhere near valid.  Looking back over this thread, there are too many complications to consider.  I'm pretty sure a creative accountant could justify six different answers, and I hate math problems with no right answer.

But as I've previously stated, I didn't buy solar panels solely as a profit-seeking venture.  There were environmental reasons, and fun technology toy reasons, and setting a good example for my kids reasons.
« Last Edit: August 29, 2018, 06:56:28 PM by sol »

monarda

  • Handlebar Stache
  • *****
  • Posts: 1193
  • Age: 62
Re: solar panel installation
« Reply #201 on: August 30, 2018, 08:06:01 AM »
But as I've previously stated, I didn't buy solar panels solely as a profit-seeking venture.  There were environmental reasons, and fun technology toy reasons, and setting a good example for my kids reasons.

Like.
:-)

Prairie Stash

  • Handlebar Stache
  • *****
  • Posts: 1795
Re: solar panel installation
« Reply #202 on: August 30, 2018, 08:56:29 AM »
I did do a net present value calculation on my expected future payments, when I was first buying the solar panels, and decided the discounted repayments were worth about 3.2% per year.  At this point, I have no idea if that analysis is still anywhere near valid.  Looking back over this thread, there are too many complications to consider.  I'm pretty sure a creative accountant could justify six different answers, and I hate math problems with no right answer.

But as I've previously stated, I didn't buy solar panels solely as a profit-seeking venture.  There were environmental reasons, and fun technology toy reasons, and setting a good example for my kids reasons.
That's fair, I'm just pointing out that your NW, assuming the panels have $0 value, will be higher (not quite yet, therres still 2 tranches coming) then if you had left the money in the market. Sometimes you get rewarded for doing something good. Next time you're on your deck drinking a beer chilled by the sun, feel free to enjoy looking at them and seeing those panels as the one time you beat the market.

I think you're downplaying your success, let me congratulate you even if you don't want to hear it.

sol

  • Walrus Stache
  • *******
  • Posts: 8465
  • Age: 45
  • Location: Pacific Northwest
Re: solar panel installation
« Reply #203 on: November 03, 2018, 01:17:30 PM »
update:

I finally got paid for my 2017/18 production, the max $5k allowable by state law, and my solar panels have now more than paid for themselves since I started this thread.

nereo

  • Senior Mustachian
  • ********
  • Posts: 15906
  • Location: Just south of Canada
    • Here's how you can support science today:
Re: solar panel installation
« Reply #204 on: November 03, 2018, 02:18:04 PM »

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.

update:

I finally got paid for my 2017/18 production, the max $5k allowable by state law, and my solar panels have now more than paid for themselves since I started this thread.

That's pretty freakin' awesome @sol - you've paid back your initial upfront cost more than a year sooner than estimated, and your energy production has more than eclipsed your usage since installation.
« Last Edit: November 03, 2018, 02:19:42 PM by nereo »

monarda

  • Handlebar Stache
  • *****
  • Posts: 1193
  • Age: 62
Re: solar panel installation
« Reply #205 on: November 03, 2018, 03:57:00 PM »
Nice, sol!

Our much smaller system installed in Dec 2011 has produced 17 MWh, still exceeding expectations. What's your MWh total production since installation if I might ask?

Ours has not paid for itself yet, but we don't have as sweet a payback here in WI.

sol

  • Walrus Stache
  • *******
  • Posts: 8465
  • Age: 45
  • Location: Pacific Northwest
Re: solar panel installation
« Reply #206 on: November 03, 2018, 06:58:21 PM »
you've paid back your initial upfront cost more than a year sooner than estimated, and your energy production has more than eclipsed your usage since installation.

and

What's your MWh total production since installation if I might ask?

both need the same answer.  I installed about 7500 Watts of panels on my roof and expected to get about 7500 kWh of production per year, based on the estimates from websites and solar installers, but have instead been getting closer to 10,000 kWh per year. 

Since my panels went live in July of 2014, they have produced 42,834 kWh.  I just walked outside and looked at the production meter.  That's 42.8 MWh in 4.3 years, or just about 10 MWh per year, and it's been worth about $800 per year in avoided utility bills because we only pay about 8 cents per kWh instead of the national average of 12 cents/kWh.  That includes some down time when one of the inverters went out for a month and had to be replaced (under warranty, free to me).

Our household energy usage has also risen significantly since installation, almost doubling after we added the Leaf and replaced our gas furnace with the heat pump, but this still works out okay.  It turns out to be more cost effective for us to use that surplus solar power to displace the gasoline in our vehicle than to sell it back to the grid, so from a financial perspective we're shooting for net zero, with no surplus.  This year will be close.

nereo

  • Senior Mustachian
  • ********
  • Posts: 15906
  • Location: Just south of Canada
    • Here's how you can support science today:
Re: solar panel installation
« Reply #207 on: November 04, 2018, 07:46:56 AM »
(asking here because you seem to keep on top of these things...)
since 2014 how has the hardware changed?  I hear there has been big drops in the cost of micro-converters... what about the panels themselves?  Seem to recall a lot of talk about how the goal for newer panels wasn't maximum output so much as better output during lower photo-intensity days (e.g. cloudy/rainy conditions).  Are 'model year 2018 panels' substantially better than the ones you put up in '14?

TomTX

  • Magnum Stache
  • ******
  • Posts: 4763
  • Location: Texas
Re: solar panel installation
« Reply #208 on: November 04, 2018, 08:36:50 AM »
(asking here because you seem to keep on top of these things...)
since 2014 how has the hardware changed?  I hear there has been big drops in the cost of micro-converters... what about the panels themselves?  Seem to recall a lot of talk about how the goal for newer panels wasn't maximum output so much as better output during lower photo-intensity days (e.g. cloudy/rainy conditions).  Are 'model year 2018 panels' substantially better than the ones you put up in '14?

Panels have gotten cheap enough as a percentage of installed cost that it is becoming more common to "overprovision" by adding some extra panels, especially ones aimed East/West to increase early/late/overcast production. More likely to have the peak production clipped by hitting the max on your inverter, of course.

Panel quality, heat sensitivity and yield vary a lot.

mycoding

  • 5 O'Clock Shadow
  • *
  • Posts: 2
Re: solar panel installation
« Reply #209 on: May 03, 2020, 12:05:47 AM »
  Interesting topic thank you.