Today I wanted to show you in brief 5 good ways to use solar energy to produce useful heat. Most people probably at this moment think about solar thermal collectors for domestic hot water, but there are many other possibilities.

Of course I will write about solar collectors, though it’s not a device I suggest to use or purchase.

I hope this article will be an inspiration for further research and reading for you.

1. Solar thermal collectors for hot water

This is the traditional way many people in modern Europe use solar energy. The solar irradiation heat the fluid circulating in flat plate or evacuated tube collectors. If frost is not a concern, this fluid is simply domestic water, while in colder climates some solution of glycol has to be used. In the latter case an additional heat exchanger must be used.

In Polish cold climate in my opinion those collectors in many cases are a waste of money. It’s much better to build your own solar collector.

2. Solar air heat collectors

In my opinion, such collectors are much better. The heat is used in lower temperature, as air can heat up the home even at 25°C (77°F), without the use of heat transfer medium, gives us better efficiency and less heat losses.

Solar air collectors of course are unable to heat your domestic hot water, they can only be a renewable source of energy for heating.

3. Trombe walls

Trombe wall is a combination of well-insulated wall, heat storage, air collector and greenhouse.

This wall is exposed to sunlight during the day, which allows it to become warmer. A part of the heat is delivered immediately to the room behind the wall, but significant part is stored in the wall itself. This heat is given out to the room during the night. And it all happens without any fan or controller.

4. Solar ovens

Solar energy can also be used to cook or bake. Solar ovens are nothing more fancy than well-insulated containers, painted black inside. They are covered with glass that allows the sun to warm it and also contains the heat inside. Some ovens also have additional mirrors that direct extra energy inside.

They can be used to bake bread or cook meat for a meal. They are difficult to use daily, though, as you don’t have enough sunny weather. And you have to bake longer in solar oven than you would in electric one…

5. Passive solar heating through large windows

The basic heat source for passive houses. Such buildings get most of the energy for heating through large windows on the south-facing wall. During winter the sun is so low on the sky that the irradiation is able to penetrate deep into the rooms.

Such system is called passive solar heating, as it doesn’t require any additional devices or energy sources. You only need to buy windows that are well insulated, or cover them with movable insulations.