The bottom line with any renewable energy solution is, of course, whether it's worth the investment. Since solar thermal systems don't generate electricity and will never be a single solution for a net-zero or net-positive home, are they worth the money?

The simple answer is, as always, "it depends". Your particular location and circumstances will always determine whether any given option is suitable so you should look for a local expert with whom you can discuss options and possibilities.

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.

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".

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).