You know what we're going to say: talk to a professional. The most reliable estimates of what equipment you'll need come from people who've already installed dozens of renewable energy systems in your area. However, we know you're going to try to figure it out for yourself, so here are some guidelines!
There are three main ways of figuring out how much PV space you'll need: daily use, net-zero and a simplified guesstimate.
Photovoltaic panels (or PV panels) are typically flat, rectangular boxes full of cells which capture the sun's energy and turn it into DC (direct current) electricity. This current can be converted into AC (alternating current) by means of an inverter and used in a normal, grid-connected home.
If you've decided to go the whole hog and switch your entire home over to renewable electrical sources, there are a few issues of which you should be aware. They may not affect you, depending on your circumstances and location, but you need to understand that it's not necessarily all roses.
Before you start looking at systems to provide renewable electricity to your home, you need to decide whether you're going to go the whole hog or not. In other words, are you going to go 100% electrical or are you going to mix in some natural gas, an old-style fireplace, a wood-burning stove or other options.
When you install a solar thermal system, you always need a collector (the bit that does the heating) and often need a tank (unless you're able to use a simple "batch system"). The tank is pretty simple but the collector format and setup is more complex.
Before you decide what kind of solar thermal system to install, you need to estimate your home's hot water use. There are two important parts to this equation: your actual water usage and your pattern of use. By changing the latter, you affect the former, so it's worth not only estimating but understanding how you and your family use water.
One of the first questions you need to ask yourself when considering solar thermal systems for hot water supply is whether you will need extra storage.
At their simplest, solar thermal systems simply heat water and send it to a standard, insulated hot-water tank, from where your home takes its supply. If the tank contains enough water for your needs, you may be able to opt for what's called a "batch system".
Solar thermal systems don't generate electricity: they just heat water. This means that they'll never give you a net-zero or net-positive effect if they're used on their own. On the other hand, they're more efficient than renewable electrical systems, have fewer demands and can take care of pretty much all your domestic hot water needs.
One of the more common misconceptions with homes using renewable energy is that they are totally independent, off-grid setups. In the vast majority of cases, this is not true: the home remains on the grid but offsets any external energy use with renewable sources so that the net cost or net use is zero (or better).
Completely off-grid, self-sufficient homes are still rare. Although the idea of renewable energy is to avoid using non-renewable sources, in practical terms this is a net effect for most people: through the year, your systems will provide enough energy that it counterbalances the grid power used. This means that your home will stay grid-tied even though you generate your own power.
