Author Topic: Going solar  (Read 4678 times)

meadow lark

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Going solar
« on: March 23, 2013, 09:42:56 PM »
Of the people who have solar power or heat, or people who have researched the hell out of it, any suggestions?  I am considering buying a solar system (haha, that sounds like I have a God complex) in the next several years.  I live in New Mexico, so we got the sun!  It would be grid-tied, no battery.  What is the most efficient use of money?  When I researched it a couple years ago it was definitely most efficient to go in this order:
1 - Efficiency, insulation, reduce use.
2 - solar hot water heaters
3 - solar air heaters
4 - solar electricity

  This house will is 750 sq ft, and we will certainly use energy star appliances, a front loader washing machine.  It has double-paned windows.  We will install low-flow faucets, and a shower head.  And we'll check out LED vs CFLs when the time comes.
  Any other suggestions on efficiency?  We will need to replace the roof in a couple years, so we will probably wait until that is necessary to actually buy any solar panels, so they don't have to be moved once they are placed.
  This house is currently a rental we will be moving into in a few years.  Does anyone know if it would make better financial sense to do this when it is still a rental?  Of course, that might make us replace the roof before it is necessary...  Hmm, I wonder if the tax benefit on replacing a roof is worth doing it 4 or so years before necessary...

Catbert

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Re: Going solar
« Reply #1 on: March 24, 2013, 02:08:04 PM »
We went tied-to-the grid solar 3 years or so ago.  It's been successful in that over a year's time we generate as much electricity as we use.  I'm not sure how much of a money winner its really been, however.   It cost around 25K minus state and federal credits of about 10k (too lazy to look up the actual figures).  At the time it was projected to pay for itself in about 12 years.  A decent deal since we plan on living in this house forever.  I would not put in a future rental until/unless that became the norm for rentals in your area.

I agree that general efficiency and insulation is the best first step (which you've already done).  Our water heater is gas and I was told at the time (by the solar power salesman) that we were better off keeping as it was rather than going for solar heating.  That may be because in Southern California the sun isn't as consistent as it may be where you are.  I've never heard of solar air heaters - they sound like more of a desert thing which isn't my neighborhood.

I *think* that solar is getting cheaper all the time so by the time your roof needs replacing it pay be a quicker payback.  (MMM commented somewhere that some day it will be a do-it-yourself, get the kit at Costco project.) 


Nords

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Re: Going solar
« Reply #2 on: March 24, 2013, 07:34:37 PM »
1 - Efficiency, insulation, reduce use.
2 - solar hot water heaters
3 - solar air heaters
4 - solar electricity

  This house will is 750 sq ft, and we will certainly use energy star appliances, a front loader washing machine.  It has double-paned windows.  We will install low-flow faucets, and a shower head.  And we'll check out LED vs CFLs when the time comes.
  Any other suggestions on efficiency?  We will need to replace the roof in a couple years, so we will probably wait until that is necessary to actually buy any solar panels, so they don't have to be moved once they are placed.
  This house is currently a rental we will be moving into in a few years.  Does anyone know if it would make better financial sense to do this when it is still a rental?  Of course, that might make us replace the roof before it is necessary...  Hmm, I wonder if the tax benefit on replacing a roof is worth doing it 4 or so years before necessary...
If you have a gas water heater then you'd need to do more research on the payback.  It might be a lot longer than the typical 3-8 years for going from electric to solar water heater.

Efficiency: 
1.  A newer, smaller, energy-efficient fridge.  After the water heater, the fridge is the #2 energy hog.  You may want to consider getting rid of the garage fridge and the chest freezer unless you're a volume buyer... people frequently buy those to "save money on bulk purchases" but rarely follow through.  If you can find a Craigslist fridge that's just a couple years old then it's a bonus.
2.  Look for a convection microwave oven (Craigslist again).  It cooks food more efficiently than a convection oven because it's heating a much smaller volume.  The new models have a longer payback because you're paying for caché and décor as well as the engineering.  The used ones have a great payback because hardly anyone appreciates them.
3.  Power strips or switched receptacles for all your vampire appliances & electronics.
4.  Consider insulating your roof with two inches (or more) of polyisocyanurate foam panels, or spraying icynene foam in the attic.  We did the former on our south roof (with 2"x2" furring strips supporting sheathing over the 2"-thick 4'x8' panels) and it's wonderful.  Put reflective foil insulation on top of the ISO panels.  (We used plywood sheathing with integrated reflective foil insulation.)  It's totally changed our indoor climate.  We rarely open the windows in summer and now it's actually a bit chilly around here on winter mornings.  While you're replacing the roof, spend a little extra for reflective Solarex shingles. 
5.  Solar exhaust fans for attic spaces will drop the attic temperature 30-40 degrees.  We also have one at the top of a stairwell to cool our cathedral ceilings via chimney effect.  However I'm not sure if this is appropriate for attics in freezing climates.

If you buy a solar water heater, buy a real solar water heater (not a water heater used for gas/electric installations).  The solar models have several different pre-plumbed penetrations for your design, and the thermocouple wiring may be installed inside the shell instead of running up the outside.  It makes a huge difference having the hot return from the roof collector going into the tank on the side instead of on top-- the former has much less reverse circulation when the pump is off.  The more expensive ("12-year warranty") tanks also have higher-quality components and thicker insulation.  Your tank will be storing water at 150 degrees (or a little hotter) so it may even be worth your while to wrap a water-heater blanket around it, or have cross-flow ventilation in your garage to keep from heating it up in August.  You may also want to keep your piping clean by installing a whole-house water conditioner (ion-exchange resin) to avoid mineral buildup inside the solar water system.  You'll clean toilets & sinks much less often, too.

Good question on the rental.  I'm not sure about the federal tax credits, but many state/utility credits & rebates are only for owner-occupied properties.  From a tax perspective, deducting it on Schedule E just reduces your rental income at your marginal tax bracket (15%-25%).  Taxing a tax credit, though, reduces your taxes at a 100% bracket...

If you already have double-paned windows then I'm not sure how much more you'll gain from UV tinting.  We can really tell the difference between one pane and two, but so far the only detectable tinting benefit is minimizing UV damage to shades/drapes, carpets, & upholstery.

Jamesqf

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Re: Going solar
« Reply #3 on: March 24, 2013, 09:10:03 PM »
The problem with efficiency upgrades, at least for me, is that I got to a point where - since my average monthly electric bill is in the low $40s - the payback time for solar electric would be about 30 years.  So not likely to happen until I can buy a used plug-in hybrid.

One point on an electric or gas water heater: turn down the temperature so that it's only about as hot as you'd want for a shower.

Kazimieras

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Re: Going solar
« Reply #4 on: March 25, 2013, 11:52:23 AM »
One point on an electric or gas water heater: turn down the temperature so that it's only about as hot as you'd want for a shower.

I would caution against doing that since depending on the water source/quality you can end up with some stuff growing in your hot water tank. Typically tanks are kept at a higher temperature in order to keep bacteria and other baddies from taking up residence. Too low of a temperature can have some health consequences, at least this is what I've read.

Jamesqf

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Re: Going solar
« Reply #5 on: March 25, 2013, 10:10:10 PM »
I've never heard of that.  I doubt if it would actually work, since many bacteria live just fine in the near-boiling waters of hot springs.  OTOH, if they grow in water heaters, why would they not grow in the cold water of your well tank?

Kazimieras

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Re: Going solar
« Reply #6 on: March 25, 2013, 10:21:30 PM »
I've never heard of that.  I doubt if it would actually work, since many bacteria live just fine in the near-boiling waters of hot springs.  OTOH, if they grow in water heaters, why would they not grow in the cold water of your well tank?

The bacteria that live in the near boiling hot springs are non pathogenic in nature (aka they don't get you sick), and actually have trouble living outside those extreme temperatures. The ones that tend to get people sick prefer around body temperature - which is not oddly the same temperature most people take their showers.

They could grow in the cold tanks, however living things hate the cold and grow super slowly most of the time (e coli can double each 20 minutes in peak conditions, which is around 37 degree Celsius) and with that temperature the flow of water keeps the bacterial levels down.

There was a great study done on this here:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2094925/

Spork

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Re: Going solar
« Reply #7 on: March 26, 2013, 08:48:23 AM »
Caveat: I haven't tried this and the setup at my house isn't really optimal for it but...

I read an article a few years back in Mother Earth on just pre-heating*.  I.e. you have a solar water heater that feeds a traditional heater.  The theory is that dumping all that cold water in a tank (or throwing it at a tankless) is what costs all the money.  Maintenance of hot: not so much.

So you could set your water heater to "safe temp" and preheat it with solar.  Win-win?


*This was really something as stupidly simple as taking an old water heater tank, stripping it of insulation, painting it black and mounting it in a "greenhouse" style box. 

Rollin

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Re: Going solar
« Reply #8 on: March 26, 2013, 11:03:45 AM »
4.  Consider insulating your roof with two inches (or more) of polyisocyanurate foam panels, or spraying icynene foam in the attic.  We did the former on our south roof (with 2"x2" furring strips supporting sheathing over the 2"-thick 4'x8' panels) and it's wonderful.  Put reflective foil insulation on top of the ISO panels.  (We used plywood sheathing with integrated reflective foil insulation.)  It's totally changed our indoor climate.  We rarely open the windows in summer and now it's actually a bit chilly around here on winter mornings.  While you're replacing the roof, spend a little extra for reflective Solarex shingles. 
5.  Solar exhaust fans for attic spaces will drop the attic temperature 30-40 degrees.  We also have one at the top of a stairwell to cool our cathedral ceilings via chimney effect.  However I'm not sure if this is appropriate for attics in freezing climates.


If you fully foam your attic like I did you don't want to vent it.  I did vent another house with a solar vent that I installed - made a big difference in attic temps.  My fully foamed attic is now "conditioned" similiar to my living space.  All the vents and roof were covered with 2 inches of blue icynene.  The theory is that your HVAC is now in 80-85 degree temps in summer as opposed to 135-160.  Makes it last a lot longer and run way less - at least 50% on both.  In winter, we use heat maybe 15 days here in Florida, but same goes - except that 30% savings more likely.  An additional bonus is that the roof is stuck on tight and very hard for a hurricane to rip it off - so I get insurance discounts.  It also has a secondary water penetration barrier of 99% - another discount.  I need a summer to edxperiment before I can document all these costs savings though.  I do read the outside temps vs. the attic vs. inside the house regularly.  These are being charted to see if the pattern expected occurs.

I have coupled this with solar hot water (three teenage kids and the Mrs can use a lot of water) that paid for itself in about 2 years (make sure it has a circulating system).  And general lighting changes - all either compact flourescent or LEDs.  No TV helps in many ways too.  Dryer and washer in garage instead of in the house - for obvious energy related reasons.  Variable speed pool pump saves $50/month too.  Shaded east and west sides of the house for summer.

You may want to reverse some of this if you are trying to save in colder climates.

Right now I don't see PVs in our (near) future.

happy

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Re: Going solar
« Reply #9 on: March 30, 2013, 05:11:22 AM »
  What is the most efficient use of money? 

The most efficient use of money I did was to seal doors and gaps between the floor and skirtings. Cost <$100. YMMV: Aussie houses are very leaky, in fact prior to 1960 we had a standard to make them so (doh!).

Second FREE big difference was to turn off peak electric hot water from 70C to 60C which HALVED the electricity cost.  There is virtually no risk going to 60C but my research led me to conclude that below 60C it was a bit more uncertain, so I haven't gone lower. Some people claim if you use a mains chlorinated water supply this is safer if you don't heat to 60C, than if you use rainwater.

I've done lots of other stuff, but they all cost many more dollars: these were by far and away the most efficient in terns of cost.

If you are doing solar hot water  the  evacuated tubes are more efficient than a PV based system.