by Greg Bryant
If we're to reduce carbon emissions, then we need to start reducing our energy needs dramatically. We also need to meet our energy needs locally, but we must do this in a way that doesn't produce more carbon (here or elsewhere) than we can absorb locally. We cannot offshore, or outsource, our obligations. We must localize energy.
This means that everyone, everywhere, must develop local technical competency, adapted to the lifestyle that the local community determines is appropriate. Not everyone needs electricity (we did without it for most of human history) but if we want it, we can't destroy the world to get it. If we produce the technology locally, we will be able to properly regulate our own production. Global industrialization defies regulation and fights restriction, so we must do everything we can to divorce civilization from it.
This means we need freely accessible, freely shared research on the alternatives to industrial production of, for example, solar power. We also need a local micro-industry making use of, and contributing to this knowledge. What local materials can we make wire from? What processes use only local resources to create solar cells?
Let's start with a few basic observations about solar power.
An average US home uses 3 kilowatts of electricity. It uses another 3 kilowatts if it's charging heavy transportation, such as an electric car. (This is only one reason that we need to severely limit the production of private cars, of any kind. Only enough for the minimum needs of community-owned carsharing.) A house needs another 3 kilowatts if there are significant power requirements for heating and cooling. Hopefully, with insulation and cycling and urban planning and other improvements, that 9 kilowatt household expenditure can be reduced to less than a kilowatt. (Note: this doesn't include upstream energy expenditure for food, infrastructure, entertainment, etc.) Still, we'll need to produce solar panels locally. Most places in the world will need to.
A few notes on solar panels on the home.
Solar panels heat up. If they are mounted flush against your roof, your roof will heat up through heat conduction. If they are raised for better ventilation and cooling, you must consider the bracing's snow weight capacity, and ability to resist wind uplift.
Solar panels become less efficient when they are hot. It is worth raising them, and dedicating some of the solar energy towards cooling the panels themselves.
If solar panels are immobile, they will have a peak distribution based on where they are pointed. Mobile or tracking panels can follow the sun and stay closer to peak output during the day.
These are just some of the reasons why solar roof shingles won't be able to directly replace contemporary roof shingles. But it is possible to create a vented false roof of better-looking tiles, for improved insulation, protection, and aesthetics. However, it would be better to find a way to make these roofs pretty with micro tracking panels, so electricity could be gathered throughout the day.
Solar panels do not deliver energy at night. If you tie your panels to the electric grid, that's a balancing problem for your electric utility (which hopefully is publicly or coöperatively owned, and doesn't distribute over long distances or transform power levels unnecessarily ). If you're off-grid, you need to find a way to store electricity if you want to use it at night. There are many ways to do this, and it's best if this is an adaptation based on the context. For example, if you're on a hill, and have enough land, consider pumped storage.
It's easy to uglify a pretty house with poorly-considered solar panel placement. Consider harmonious unfolding for your design.