TreeHugger has been looking at the issues of solar power vs energy efficiency for years, how people pile solar panels on the roof to offset energy consumption instead of insulating, increasing supply instead of reducing demand. But since I first complained about this back in 2012 the price of rooftop solar has dropped in half. Under those circumstances, does it still make sense to tout efficiency over solar?
Over on Energy Vanguard, Allison Bailes III has a look at the numbers to see which is a better investment, writing The Cost of Solar Energy Keeps Dropping, But... He first points to an earlier article on Green Building Advisor by Steven Nadel, who says solar and energy efficiency need to work together like peanut butter and jelly. (or, given the Jewish holiday season and the contents of my fridge, lox and cream cheese) Nadel explains why people have been going solar first:
In recent years, some solar companies and some consumers have been employing a solar-first strategy in the residential sector — installing solar systems without paying much attention to energy efficiency. This strategy has been spurred in part by substantial solar tax credits, net-metering rules in place in most states, and the availability of solar financing that reduces or even eliminates the initial purchase price, replacing the up-front cost with monthly payments that extend over many years.
Whereas efficiency means renovations and mess and money up front. However the data show that even with the current price of solar and all the subsidies and support that solar has, efficiency is still far cheaper. He concludes:
Energy efficiency will generally be less expensive per kWh than solar. And by lowering consumption, energy efficiency will stretch the available rooftop solar resource farther, allowing solar to serve a higher percent of residential consumption while also allowing a smaller and less expensive solar system. These are two simple analyses but they make a clear case that jelly (efficiency) is needed to help peanut butter (solar) do its best.
Allison Bailes comes to the same conclusion and adds:
Here's the thing. The battle between solar and efficiency isn't a battle at all. They need to be working together. Yes, we need solar energy. But we can't forget about energy efficiency just because the installed cost of solar has fallen so much. They need to work together.
Bailes also reminds us of the Duck Curve, where the utilities have to be designed to cope with demand occurring after the sun goes down. I explained this on MNN, how "power use peaks now at in the morning and end of the day, but as more and more solar comes online, the power used in the middle of the day drops significantly. But companies need to make sure the power plants and the distribution system ramp up fast to deal with the evening peak, which is pretty much the same with or without the help of solar power. No wonder the utilities are freaking out."
Designing for efficiency reduces that demand, because efficient houses act like a thermal battery. I have written that “a really efficient building can trim the peaks and troughs of our energy production as effectively as any other kind of battery. A properly designed house would need so little cooling or heating that it can be maintained at any time without making a big difference in energy use, without all this complication.”
There are a couple of other points that Allison Bailes and Steven Nadel miss that tip the balance even more toward efficiency first instead of solar first.
Resilience. As Mike Eliason notes, also writing in Green Building Advisor, “A grid-tied PV won’t keep you warm at night during a blackout.”
Urban Design. I have written: “Rooftop solar disproportionately favors those who have rootops, preferably big ones on one-story houses on big suburban lots. Those people tend to drive a lot.” We have to live more closely together in walkable and cyclable communities, and that means less roof area per capita. And as I also wrote on MNN, “Young, urban or poor people living in apartments don’t have a lot of roof or the opportunity to install solar panels, and they'll probably pay more for electricity. So this becomes yet another subsidy to the American suburbanite. However, efficiency works for everyone everywhere, around the clock.”
Trees. I know, it is not the biggest issue, but the best air conditioner in the world is a big tree that shades the house. Mat notes: “The net cooling effect of single, young healthy tree is equivalent to 10 room-sized air conditioners, running for 20 hours a day. 10 air conditioners, a single tree!!” Trees can reduce cooling loads by 15 percent. But tree power and solar power do not play nice together and proponents of each have been fighting in the courts for years. And given the name of this site, it should be clear whose side we are on.
Nadel concluded that solar and efficiency go together like peanut butter (solar) and jelly (efficiency). Bailes concludes “So, yeah, solar energy has sex appeal. But a comprehensive energy strategy includes lots of energy efficiency, too.”
Nadel and Bailes are treating them with some equivalence; I do not think that's true. Efficiency is better for the electrical system, for resilience, for urban form, for the environment and for the trees. It's good for everyone. Reducing demand is better than increasing supply. I will have a jelly sandwich, please, hold the PB.