Typical U.S. Homes Reduce Their Energy Bills Most Significantly With Rooftop Solar Energy Systems

[jpak]

http://www.marketwatch.com/story/typical-us-homes-reduce-their-energy-bills-most-significantly-with-rooftop-solar-energy-systems-2010-11-09?reflink=MW_news_stmp

A White Paper entitled "Reducing Home Energy Costs by Combining Solar and Energy Efficiency" was released today showing that typical U.S. homes will reduce their energy bills the most by generating their own power -- rather than implementing energy efficiency measures. The complete text of the paper is available for download at http://www.westinghousesolar.com/whitepapers. The White Paper was written with the support of the California Solar Energy Industries Association (CALSEIA) and Westinghouse Solar.

The White Paper used Department of Energy software to evaluate three different ages of homes (old, typical and new) in ten cities in the U.S. for a total of 30 different test simulations to determine what combination of energy efficiency and renewable generation makes the most sense for homeowners. The conclusions are significant given that the residential sector consumes 22% of the energy in the United States, and there are only two ways to structurally reduce a home's energy costs: energy efficiency and energy generation.

The results of these 30 different home simulations are that climate, local utility rates and home condition are the biggest factors in determining what are the most cost effective energy savings measures. Lighting retrofits are always cost effective. Weatherization and insulation energy efficiency measures are most cost effective in old homes in cold climates, but are not cost effective in newer homes or in temperate climates. Basic building shell and ventilation energy efficiency measures are most cost-effective in cold climates, but have long paybacks in more temperate zones. Rooftop solar power systems have good paybacks regardless of home condition in sunny areas and in areas with either high electric rates or high solar incentives. Solar thermal systems have good paybacks when the fuel source for hot water is electricity. Upgrades to Energy Star appliances and equipment are generally cost-effective when replacing broken or obsolete equipment, but are generally not cost effective when the existing equipment is still functional (analogous to not upgrading to a new, higher mileage car if the old one still works).

"In almost all of the U.S. housing stock built since the mid-1980s the 'low hanging fruit' of basic energy saving measures have already been harvested through energy efficiency regulations and rebate programs for energy efficiency measures," said Sue Kateley, Executive Director of CALSEIA. "Consequently, for a typical home in the U.S., rooftop solar energy systems (electric and thermal), will generate six times more energy than can be saved with lighting, weatherization and insulation retrofits combined. Generating the remaining energy required by the home will have the biggest impact on reducing home energy consumption. Put simply, it is time for policymakers to reevaluate loading order priorities to ensure that the state and national policies to reduce energy consumption will be achieved in a cost effective manner."

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[phantom power]

1. ???

They must not be comparing savings-per-dollar-invested.

:shrug:

[AlecBGreen]

4. i had the exact same thought

nt

[joshcryer]

8. edit: correction, it appears they are. I don't see how a 2kw system can provide...

...such savings, though.

[joshcryer]

9. dupe

[joshcryer]

13. $10,000 3 kw rig at 20% capacity factor here in Colorado:

(3 * 365 * 24) * .20

kilowatts * days * hours / capacity factor

5256 kwh a year.

Residential electrical prices are 11.25 cents a kwh here in Colorado (some of the highest rates in the country).

5256 * .1125 = $591 in savings, per year.

The whitepaper is claiming $714 savings a year and a payback time of 13.5 years.

Savings are off but not by too much. I will have to determine average CO usage to determine if their payback time is accurate but I got to get going.

Also 20% capacity factor is going to be wrong. Doing it for 10% is much more reasonable but I'd get yelled at for "cooking the numbers" or something. Point is that their calculation is off and there's something wrong with their methods.

[Fledermaus]

23. Solar Radiation for Flat-Plate Collectors Facing South at a Fixed Tilt, Uncertainty +- 9%

Its better to use real data then make up a capacity factor.



Solar Radiation Data Manual for Flat-Plate and Concentrating Collectors

http://rredc.nrel.gov/solar/pubs/redbook/PDFs/CO.PDF

http://rredc.nrel.gov/solar/pubs/redbook/

[Lorien]

2. Amazing that this is getting unreccs

seems like common sense...but then we did have that huge influx of fossil fuel apologists after the BP gusher.

[joshcryer]

10. Get a bad reputation people unrec regardless.

[OnlinePoker]

3. A company that makes solar equipment has a study that says solar is good.

I'm shocked.

[joshcryer]

11. The source document is not very comprehensive, but that doesn't mean it's innacurate.

We need harder data.

[kristopher]

5. Kick

[Fledermaus]

6. How can you tell if a solar panel is working by taking its temperature?

A working solar panel is cooler that one that is broken. 11% of the suns energy is turned into electricity reducing the temperature of the panel.

A large array will help keep a home cooler just from the shade. Usually they are 6 inches above the roof and they provide shade.

[Confusious]

7. lets not mention the 30 large it costs

maybe going as low as 15 out of pocket.

Most people I know can't stretch their budgets that far. Maybe 1 out of 100. and he's a millionaire.

[joshcryer]

12. They're assuming $5.50 a watt, which is actually higher than it is here...

[quakerboy]

14. Overestimate, I think

I got a quote from a local installer, just to see what the numbers were. The system install is about 21k, but by the time all the tax and instant credits are calculated, it goes down to 5k for a 4kWh roof system. That starts looking a lot more affordable.

[phantom power]

15. That doesn't change the cost, it just means taxpayers are picking it up.

[quakerboy]

19. Ok. but be fully fair about it

How much of our energy comes from petrol powered stations and coal powered stations? And how much of the true cost for those are tax payers picking up? And how much of the environmental cost is being passed on into health care, and how much more onto future generations.

But, setting that aside, the person I was responding to was commenting as to the out of pocket costs of a solar system. And the credits and tax rebates play a huge roll in figuring out a persons immediate cost to install a system.

[joshcryer]

21. Tax payers are going to pay for fossil fuel use, eventually.

It's too bad they're not actually being made to do it now...

[Confusious]

16. Average American home uses twice that 4Kwh

Maybe your state gives more in tax credits.

[quakerboy]

18. Cutting ones energy cost in half is significant, no?

Its possible so on the credits. Oregon is nice that way.

I dunno. I was doing the math, and if I had the money, it might almost be worth buying a cheap bit of land somewhere and slapping in a grid feed system. Assuming that energy costs keep rising, it might just pay for itself in not to terribly long.

[txlibdem]

17. Rooftop solar is a good thing, if you can afford the upfront costs

I don't know where the other poster can get 4kW for $5k out of pocket. In my area, quotes are minimum $10k. Maybe they're just talking parts and materials without labor?

The best application for rooftop solar is to provide fuel for an electric vehicle. First, you need a smaller solar array and high gasoline prices decrease the payoff time significantly.

[happyslug]

20. The key is the phase "Since the mid 1980s".

Basically in homes built since the 1970s energy efficiency was built right into the home, most building codes require it AND most home owners BUILDING a home required it. If the home was built for "stock" the builder installed energy efficiency into the home for it provided a higher price and thus profit margin.

Thus it is probably true that for homes BUILT since 1985, a solar electrical energy system would be more cost effective then additional insulation. How much more insulation do you need if you already have more then the called for maxi mun in your area of the Country? The return on investments of such additional insulation will be quite low (as opposed to older homes where the biggest saving will be the insulation of insulation and replacement of old single pane windows).

Just pointing why this may be true, but given most homes were built prior to 1985 NOT as big a deal as the headline makes it out to be.

[joshcryer]

22. The numbers are definitely off, and payback time is going to be into 15 years, but it's promising.

As prices continue to drop it will only get better. Once it hits $10k payback 5 years, I'm in.