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Energy Solutions

Green Building Myth: Adding Solar is the Best Way to Green a Home

While highly visible, adding a solar energy system is not the best place to put your money in greening a home

This home in Maumee, Ohio, built by Decker Homes of Lambertsville, MI, has a building-integrated PV system on the roof.
Image Credit: Decker Homes

The last several weeks I’ve written about common myths of green building: that it has to cost more to build green, that green building is mostly about materials, that green products don’t work as well as conventional products, and that it’s hard to find green products. This week I’ll cover the myth that adding solar panels is the best way to green a home.

Without question, solar-electric (photovoltaic, PV) or solar water heating panels are the most visible green feature of many environmentally responsible homes. Either roof-mounted or installed on separate racks, those solar panels are in full view, they’re unusual enough to be noteworthy, and they convey–almost shout–a commitment to the environment. And rest assured, I’m a huge fan of both photovoltaics and solar water heating. (My first two real jobs–in New Mexico and then Vermont back in the late ’70s and early ’80s–were for organizations advancing solar energy, and solar is still dear to my heart.)

But I strenuously resist the temptation of builders, remodelers, homeowners, and commercial building owners to green their buildings simply by slapping solar panels on the roof. Solar should be the icing on the cake–added after doing all the really important work of improving the energy performance of the building envelope and upgrading heating and cooling systems, appliances, and lighting with top-efficiency products.

These measures aren’t as visible, but they usually yield far greater energy savings, financial return, and environmental benefit than a comparable investment in solar. Homeowners wanting to green their existing homes should start by getting a comprehensive energy audit to identify–and prioritize–energy saving measures. Likely measures will include adding insulation, upgrading windows (perhaps with new, low-e storms), air-tightening, replacing incandescent light bulbs with compact-fluorescent lamps (CFLs), replacing older heating or cooling systems, and switching to more efficient appliances. To reduce water heating costs, start by reducing your use of hot water by installing water-conserving showerheads, clothes washers, and dishwashers. After these investments, if your budget permits, by all means add a solar water heating or solar-electric system.

Anyone thinking of building a new home should hire an architect or designer familiar with ultra-low-energy building practices, including passive solar design (a less noticeable but usually more cost-effective application of solar energy). If you do a really good job with all this and get your heating, cooling, and electrical loads low enough, you then might be able to satisfy all of those needs with solar–creating a “net-zero-energy” house.

The temptation to start with solar is strong, especially with the very attractive 30% federal tax credits that exist for solar systems (see “Tax Credits for Solar Energy Systems”). Such generous solar tax credits, I fear, will result in a whole lot of money going into solar systems that yield considerably less energy savings than would have been realized by putting that money into energy conservation. When solar systems–especially PV systems–are installed on inefficient houses, the percent savings and return on investment can be very low; if you’re spending that much money (and the rest of us tax payers are helping out by subsidizing the tax credit) you might as well get some boasting rights!

Yes, you should install solar water heating and solar-electric systems, but before you do that you should invest in the low-hanging fruit of energy conservation.

I invite you to share your comments on this blog.

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5 Comments

  1. Lucas Durand - 7A | | #1

    Good advice.
    Martin's blog on the energy-efficiency pyramid:
    https://www.greenbuildingadvisor.com/blogs/dept/musings/energy-efficiency-pyramid

    Renewable energy ahead of conservation measures puts the cart before the horse. I'm guessing a smaller total capital investment is required if you put the horse and cart the right way around.

  2. Joseph Benga | | #2

    Have your cake and eat it too...
    Alex,
    I agree that homeowners and business should look at their whole energy profile and take care of the items that bring the most return on investment. Changing light bulbs, caulking, energy star appliances, etc. are no brainers. However, I believe you can do both the solar and the more traditional green initiatives, it just takes educating the consumer on what the options are with a realistic and honest explanation of the pros and cons of those options.
    Solar is evolving at a rapid pace. Prices for PV solar panels have been dropping considerably over the last year which is shortening the payback period if a direct purchase is chosen. However, probably the most important development in the solar industry over the last 3 years is the use of PPA’s (Power Purchase Agreements). PPA’s are not new in the energy industry, but they are new for solar. PPA’s are becoming almost mandatory on commercial PV projects and they are starting to gain traction on residential projects. For those that don’t know what a PPA is I will give a condensed explanation; the owner pays no system or installation costs, but only agrees to purchase the power generated by the system at a similar KWh rate to what they would normally pay their local utility. Even with a yearly escalator of 3 to 5 percent, in the long run, the customer will pay less per per KWh after a few short years than what they will be paying their utility. The owner also has no maintenance obligations. So, since no upfront money is being expended on the PV system the business or homeowner can use that money to do the other green initiatives.
    Another thing that should be considered is that solar panels are warranted for 25 years. What other green product carries that type of warranty? Labs like NREL have proven that solar panels 30+ years old are still producing power. So, after the payback period, that is free energy. Yes, inverters don’t last that long, but they are getting better. We are starting to see 10 and 15 year warranties. Energy Star appliances will be lucky if they last 10 years. You will, replace that appliance 3 times in course of the life of a solar PV system.
    I will make one final observation; Geographical location will also determining factor on when you should invest in solar. In the extremes weather areas like the New England states or the desert south west, caulking, insulation high efficiency HVAC systems should probably be 1st and foremost. In area’s like San Francisco (where I live now) heating and AC is less of an issue. Also irradiance for your location is a driving factor. There are a lot more intangibles that go into doing the low hanging fruit or solar, but that’s for a deeper discussion on another day.

  3. Lucas Durand - 7A | | #3

    A cart is good, but the horse should still go out front.

    Another thing that should be considered is that solar panels are warranted for 25 years. What other green product carries that type of warranty?

    I don't know about warranties, but insulation and a good air barrier could last the life of the structure and also require little or no maintenence.

  4. Joseph Benga | | #4

    Horses, Carts, Cakes...
    Lucas,
    I figured someone would point out insulation. I agree with you, but only if it is installed correctly. And not all manufactures provide a warranty. I have taken down too many walls where the insulation was over compressed, not fully covering the full height of a stud bay, full of dirt through air infiltration, mold (fiberglass itself does not support mold, but the contaminates that imbed between the fibers through air infiltration supports mold). Also, rodents love living in fiberglass. There are other insulation products but fiberglass is the most commonly used and the others types have issues also. So, based on questionable installations, are you getting the benefit of the full R-Value over the life time of the building?
    For my own education I went to different insulation manufacturers web sites and found warranties go from zero, to one year, to limited lifetime. One of the biggest and best known (think pink) has no warranty on their insulation products, but they do show warranties for their other products.

  5. Bryan Turner | | #5

    Well said. The word picture
    Well said. The word picture you draw with solar as the icing on the cake is perfect.

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