Over much of the years after the crisis of the 1973 oil embargo, I was reading NASA technical bulletins delivered by mail each month.
I learned that a coil of cheap black pipe is the most cost effective solar water heater period — a loop on the roof. The pipe can degrade and requires attention to be safe and secure, but it works.
That anything dark brown, green or blue absorbs no less than 97% as effectively as anything costly solid black in order to capture heat. The cost benefits of hi-tech and ultra-absorption systems usually fail.
That piles and piles of cheap rock or huge tubs of (safe) water under and near where you live at night will keep and convey more heat (or cool) than a dozen new technologies, tax incentives or sales discounts.
That discovering the heat gain/loss angle within 10 or 15 degrees of a window or a wall can alter a monthly utility bill more than 30%.
Temperature is where you find it. Often three feet above or fifteen feet under.
I was the State of California’s #88 license as a Certified Energy Manager, founder of the western branch of the Assoc. of Energy Engineers, held an 8000 store contract with the Independent Grocers Association to teach owners how to insulate, install usage timers and heat curtains that you might remember over the milk section, plus energy manager of 11,000 church buildings for the Cal. Ecumenical Association.
Because so much of “new energy” merely boils down to dark surfaces, shadows, angles, and old fashioned “brains”, the commerce of “new energy” did not become profitable during my generation. Even these days, it’s a risky gamble to expect any new energy option to suceed.
For cheap energy at home: Color, angle and mass remain the most effective, the least costly, the most neglected.
Temperature differential is the first tool to move energy. Shade, height and mass are the methods.