What they produce
Photovoltaic panels turn light into electricity. Solar thermal collectors absorb radiation and heat a fluid, which passes the heat on to the water in the hot water cylinder. They are different technologies, with different roles.
A quick comparison
| Aspect | Photovoltaic | Solar thermal |
|---|---|---|
| What it produces | Electricity | Heat for water |
| How it is used | Appliances, lighting, battery, grid | Domestic hot water, sometimes heating |
| Key components | Panels, inverter, optional battery | Collectors, solar cylinder, pump station |
| Best when | You use electricity during the day or have a battery | You use hot water steadily |
| Watch out for | Shading, orientation, inverter | Excess heat in summer, frost protection |
When to choose each one
If electricity is your main cost, photovoltaics is the place to start. If hot water accounts for a significant part of your consumption, especially in summer and in large households or guesthouses, a solar thermal system can be useful. Some households combine the two, but each system has its own installation and its own cost.
Sometimes water can be heated with photovoltaic energy, through an electric water heater or a heat pump; this is a third option, with its own advantages and limits.
Further details
Read the pages on photovoltaic panels and solar hot water systems. If you also heat with wood, see the fireplace with a heat exchanger.