I want solar panels that can look and function like a normal roof and will keep working for hundreds of years and not significantly damaged by bullet holes and not harmed by grapefruit-sized hail. I also only want temperatures slightly higher than room temperature (but not damaged by high temperatures such as fire or not cooled in full sun on a hot day). I figure the key requirement of the materials is to have a very low coefficient of expansion so different materials are not harmed being bound together. A surface of microscopic grooves will capture more light as any light reflected off the surface will just reflect to the other side of the groove for a second chance to be absorbed. This will also prevent infrared light coming off the hot surface from going into space but rather hitting the other side of the groove to be absorbed. The obvious problem is that these grooves will just fill with dust if exposed to the air. Evacuated tube collectors and a lot of high temperature situations including the surfaces of space vehicles that need to survive reentry are made of a type of glass that has a very low coefficient of expansion. There are two types of responses to infrared light that are important to solar collectors and they are generally only good with one of these two for most materials. One of those factors is how much of the infrared light (and visible light too) that gets absorbed instead of reflected. Generally the best of these are black in color. The other factor is how much infrared light is emitted from the surface due to the temperature of the surface. Generally metals and thermally conductive materials are good at this (emit very little infrared light). This is why metal gets so hot in the sun even if it is shiny. The solution is the oxides of certain metals which are black in color but only due to the single layer of oxygen atoms stuck to the surface metal atoms. One of these metals is nickle and another is platinum (I will have to double check this as I am going by memory). One metal alloy with a very low coefficient of expansion is a particular mix of iron and nickle... they are still not sure why this particular alloy has such an unexpectedly low expansion. My idea is to take a layer of scratch resistant glass made for cellphone screens and cover it with a thin layer of aerogel that is relatively clear then cover that with this low-expansion glass and etch it for the grooves then vapor-deposit the metal oxide then the iron-nickle alloy thick enough for welding. Then weld lots of metal fins on this for conducting the heat to the surface below. Trays of a ceramic material (there are a lot of ceramic materials with a low coefficient of expansion) with small cups for holding liquid are designed for the fins welded to the unit described above to go into these cups. The cups are filled with paraffin wax designed to melt at the desired temperature (slightly above room temperature). On the underside of this ceramic layer will be grooves for a refrigerant to make a "heat tube" to conduct that heat to the top of the collector where finned pipes will condense the vaporized refrigerant to return to the underside of the ceramic layer. A layer of butyl chalking can be added to all surfaces of this heat pipe area to seal up any holes such as bullet holes.
I usually see "green" buildings built and promoted by rich people who try to say they are saving the world due to global warming or some other BS to green-wash their activities. Sure, buildings which use little to no energy are definitely doing your part to not contribute to greenhouse gases but this is like plugging a pin-hole in a sinking ocean-liner... too little too late. My goal is far more pressing... dealing with economic collapse but from the perspective of being one of the "99%" of poor suckers with no money to lose in an economic collapse. When USSR fell, it was simply that the government's money was no longer useful for buying stuff so they could no longer pay for police and everybody else who worked for the government enough for them to keep working. Because the black market was so strong, USSR just turned into Russia with the black market mob leaders taking rotational positions in the positions of power. Venezuela also had economic collapse but without as strong a black market so people starved as there was nothing to buy at any price in any currency. If (or more likely "when") the economy of my country or your country fails, a building that does not need electricity or gas to remain comfortable will go a long way to keeping you alive and making stuff you can trade or sell. Greenhouse tech and ways to raise small mammals indoors will also help. Of course you are going to need to make these things legal and rather hidden for the time before the unpredictable economic collapse. Then after things go bad, you are going to have to not be obviously advantaged or someone is going to be stealing or damaging your advantages. Modesty is the key to looking normal but helping other poor people to do the same stuff as you also keeps you from being a target. So, renovating old houses then selling them to newly-formed housing coops and have their payments going to a non-profit making intellectual property like books and movies should keep me funded without actually owning anything worth stealing or damaging.