Solar Thermal describes solar energy devices that capture the sun’s light as heat (to create a clear contrast to Solar PV electricity). This is more efficient, generally, for processes that actually need heat (such as creating hot water for washing). It is most familiar application to Sydneysiders as Solarhart rooftop solar hot water units.
Solar Thermal at its most basic level is a mature, simple and well understood concept. The breakthroughs now are coming in the form of:
- ways to store heat (such as with molten salt, refrigerant, or even water) for use when there is no sunlight;
- reducing the rate at which heat is lost to the surrounding air (such as with evacuated tube collectors for home hot water systems);
- increasing the temperature at which the heat is captured (with concentrator lenses, or with arrays of mirrors); and
- increasing the period of time during the day heat can be captured (by tracking the sun as it crosses the sky, possibly with a dish).
Storage provides opportunities to supply baseload power, whilst the higher temperatures reached with new technologies means better compatibility with existing coal fired generation plants.