Thermal solar energy

Photovoltaic panels aren’t the only way to produce electrical energy from Sun. In this post will be shown the thermal solar energy.

Working principle

Mirrors in shape of trough focus sunlight. In the focal point there is a dark tube, because dark color absorbs more heat from light. Inside the tube, there is synthetic oil which can reach temperature of 450ºC. To obtain temperature until 200ºC, it is used demineralized water or ethyleneglycol (C_{2}H_{6}O_{2}). In the future the fluid will be replaced by molten sodium, because it allows high temperature without too high pressure.

The heated liquid goes to a heat exchanger, where it is produced steam to turn a turbine and produce electrical energy. After pass through the turbine, the steam is condensed and goes to the heat exchanger in form of water.

This energy system can be complementary with a gas power plant to produce steam in cloudy days or during the night.

Other type of thermal solar energy

This is another system to obtain thermal solar energy. It is used to heat water.

A liquid is driven by a pump to the tubes which receive solar light, the sunlight heat the tubes. The hot fluid leaves the collector to a heat exchanger and hot water is produced for consumption. A controller with temperature sensors is used to control the pump and a boiler is used as reserve in days there is not enough solar radiation.

In some solar panels, the heat exchanger stays closer to solar collector.

Comparing to photovoltaic panels for generation of electricity

I wrote 2 posts about photovoltaic panels. Click in the buttons below to read the posts.

Photovoltaic panels (Part 1)Click here

Photovoltaic panels (Part 2)Click here

The advantages of thermal solar energy are:

• Can work with other fossil fuel sources, reducing it’s environmental impact;
• The second type ones can reduce the necessity of electric shower.

The disadvantages of the trough type are:

• Requires plain terrain to installation;
• The best spots can be far from transmission lines;
• Needs water for cooling, depending on the local can be hard to find.

The advantages of photovoltaic panels are:

• Can be installed in many places, including urban areas, saving up in the transmission;
• Low maintenance cost.

While the main disadvantage:

• Still have low efficiency.