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Solar Thermal vs. Photovoltaic (PV) - Which Should You Choose?

When most people think "solar" they think in terms of solar power - electricity! Solar electric systems, or photovoltaic's (PV for short) allow you to power your home with the sun as fuel.

But if you're shopping for your first solar system, it pays to do your homework. PV isn't the only type of solar energy out there - and it may not be the most sensible place to start. If you are an average to heavy user of hot water - or would like to be - a solar thermal system may be your best bet.

Click here to use our online Solar PV Calculator

Solar Water Heating the benefits

Solar thermal, or solar hot water, uses energy from the sun to heat your domestic hot water supply. Put simply, it works like this: an antifreeze solution flows through collectors mounted on your roof, the side of your house or on the ground. The solution is pumped to a heat exchanger, where the heat is transferred to your domestic hot water supply. The heated water is then kept in an insulated storage tank until you're ready to use it. Solar thermal can also be used for space heating purposes.

Solar Hot Water vs. Solar Electric: A Cost Comparison

The cost to put in a solar water heater is not much different than installing PV. Solar thermal panels cost about the same as PV panels per unit, and the balance of the system plus labor is usually comparable in price.

The difference is in efficiency. Thermal panels average about 40 square feet rather than 15 square feet for the PV collector. That means you'll get almost 2 1/2 times the solar energy coming in. Plus, the thermal panel converts over 50% of that energy into heat, while a good PV panel will average 15% conversion.

Add it all up and the solar water heater will give you about 10 times the energy output per dollar invested.

What's Your Best Choice?

Is solar thermal always the best choice? Not necessarily. If you use very little hot water you may not be able to take full advantage of it - but most people benefit from putting in solar water heating first unless they the feedback tariff as an investment set precedence. Fulfilling your domestic hot water needs with a properly sized system will give you a lot more benefit for your money invested.

Once you've done that, it makes sense to add solar electric. The advantage of PV is that you can sell your excess solar power to the grid where the Government have set guaranteed tariffs index linked.

If you have the finances of course it would be a benefit to install both systems. This way you get the best of both generating heat/hot water and electricity. Please feel free to look at the tariffs that are current by clicking onto our Tariffs Section.