Before we begin, we would like to remind you that there are two types of solar panelsphotovoltaic solar panels, which are those that directly generate electricity due to the chemical reactions produced by the panels themselves, and the solar thermal panels or heatersThese are those that use the sun's energy to heat water, and with this, either to use it for domestic use as it is or to take advantage of the pressure of the steam generated to create electrical energy from a turbine driven by the steam in question. This time we will show you how to making solar thermal panels.
First, let's be a little clearer about the circuit that will make the water to be able to use it in our home, here is a diagram of everything:
We can distinguish two main parts in this project, the tank part, which is where the hot water will be stored, and the panel part, which is what will actually heat the water. The supply tank belongs to the normal circuit of each house, you don't have to have it.
The idea of operation is to use the greenhouse effect to concentrate the sun's rays and its heat between the tube or pipe that will carry the water and the greenhouse housing. I have seen three basic ways of doing this, with soda cans painted black, with the glass of fluorescent bulbs and with PET plastic bottles. For me personally, the latter seems to be the most appropriate.
The steps to follow to create this solar thermal panel are as follows:
1.- Get a bunch of plastic bottles of the same size, remove the stickers, glue and caps. The number of bottles to collect varies depending on the size you want to build. The normal size is 5 bottles per row and about 25 rows, that is to say 125 bottles, so keep up the search ;D
2.- Cut the bottom of the bottles to the same height, it should be about 30cm long.
3.- Collect as many TetraBricks of milk or juice as bottles we are going to use and give it this shape, and paint the part facing the sun black (the smooth part facing the sun and painted black, the part with the folds facing downwards).
4.- Get copper or black plastic tubes with the same diameter as the mouths of the plastic bottles (normally 20mm) and the length of the 5 bottles joined together (about 105cm). Introduce the bottles until the mesh is complete (remember, 5 bottles per row in 25 rows), you must also introduce the TetraBricks underneath the tube, as shown in the second image:
5.- The top and bottom joints will be connected with this type of T-piece and connected to each other with the same tube (8.5cm long) that you used inside the bottles, the elbows are for the terminations (we will only use two per panel), remember that one of the top corners must have a T-pipe (hot water outlet) and the other with an elbow, and at the bottom, the opposite corner in T (cold water inlet) and the opposite corner with an elbow.
6.- Remember that the whole panel assembly must have an inclination towards the hot water outlet side, this is achieved by leaving about 4 cm of distance towards the floor on that side. In addition, the good orientation is about 45º with respect to the floor. When we have the whole panel assembled, it will look something like this:
The tank is somewhat more complicated to build (and its size will depend on the use of water in your home) as we must differentiate very well the water inlets and outlets (six in total, three inlets and three outlets) and where they will go, here its scheme:
Note: The percentages you see on the sides of the tank are the heights of the different holes.
1.- It is the water inlet from the normal mains water supply, it has a device, like the one in the toilet cisterns, which prevents water from continuing to enter the tank after it is full. It also has a water dosing device so that the water does not mix with the already heated water:
The dosing device will go just after the water inlet pipe, and surrounding it will be a tube that will reach from the upper edge of the water level to the bottom of the tank, leaving some openings so that the water can be included in the tank.
2.- It is simply a hole so that if the system of 1 fails, it does not overflow from above, but from there.
3.- This would be the hole to supply the house with cold water.
4.- This is where the cold water inlet for the panels will go. This hole will be fitted with a system to regulate the temperature of the tank manually:
If we put the system horizontally, it will take cold water and heat it (summer mode) and if we put it vertically, it will take hot water and heat it even more (winter mode).
5.- This is where the house will be supplied with hot water. This also has a similar system:
When this system is in horizontal position, it will take all the water from the hot water side (winter mode) and when it is in vertical position it will take both hot and cold water (summer mode).
6.- This other hole is where the heated water from the panels will come through.
The tank can have another external tank so that by filling the gap between them with an insulating material, the heat is better stored in our main tank, you can see an example here:
With the tank and panel finished, the only thing left to do is to join them together following the completed circuit above and start to enjoy our heater.
Any questions regarding the solar thermal panel or heater; Link.
Full PDF tutorial in English created by How to do; Link.
The documentation for this article was obtained from Ikkaro, Gratis Energia, ISon21, Make and the PDF created by the Brazilian government in collaboration with José A. Alano.