What is a solar thermal water heating system?
There are two basic types of solar panels: flat panels and evacuated tubes. Evacuated tubes are usually more expensive, but easily outperform flat plate collectors in certain conditions.
Evacuated Tubes consist of a copper pipe running through the middle of a glass tube which is sealed to create a vacuum. This design helps to avoid heat loss through convection and radiation. Evacuated tubes suit colder regions where the sun is less effective.
How does solar thermal work?
- In the simplest panels, Sun heats water flowing in a circuit through the collector (the panel on your roof).
- The water leaving the collector is hotter than the water entering it and carries its heat toward your hot water tank.
- The water doesn't actually enter your tank and fill it up. Instead, it flows into a pipe on one side of the tank and out of another pipe on the other side, passing through a coil of copper pipes (the heat exchanger) inside the tank and giving up its heat on the way through.
- You can run off hot water from the tank at any time without affecting the panel's operation. Since the panel won't make heat all the time, your tank will need another source of heating as well-usually either a gas boiler or an electric immersion heater.
- The cold water from the heat exchanger returns to the panel to pick up more heat.
- An electric pump (powered by your ordinary electricity supply or by a solar-electric (photovoltaic) cell on the roof keeps the water moving through the circuit between the collector and the water tank.
What are the pros and cons of solar thermal?
| Advantages | Disadvantages |
|---|---|
| Provides both the energy efficient of solar and the consistent temperature of gas or electric systems | A booster is required to bring the temperature up to the desired setting |
| Most solar hot water heaters will already offer a gas or electric booster as part of the system | The booster will need some sort of fuel to work; how often is needed will determine how efficient your system is |
| Buyers can claim substantial and federal government rebates for these systems | The initial cost of purchase and installation is greater than conventional gas and electric systems |
