TOP 5 methods to increase efficiency of a solar collector

Описание: This video will not describe traditional and well-known methods. For example, I will not describe this Danish solar collector with this additional polymer film which significantly increases the collector efficiency if it must produce heat of high temperatures. This type of solar collector forms the world's largest solar thermal station which produces heat for the district heating of the Danish city of Silkeborg.

Or for example, we understand that reducing the distance between these pipes of the absorber of a solar collector increases its efficiency Therefore we can come up with the idea of this solar collector with this absorber, which was made in Finland from two thin sheets of stainless steel. Or we can come up with the idea of this homemade absorber which should be placed under a glass sheet, and now I show how that absorber was made of steel sheets.

So, I will not talk about traditional methods, for example, about radical increase in efficiency of a collector due to selective coating of its absorber, or about increasing the thickness of the thermal insulation of the north wall of a collector. However this video will describe a ranking of the following 5 non-traditional methods, from the least effective to the simplest and most effective method.

We know about these solar panel rotation systems according to the movement of the sun across the sky from morning to evening. A similar system is called a “tracker”, and it increases the electricity production from its solar panels by 20-40 %. These percentages can be noticeably greater for cases where a solar collector is installed on such a tracker, especially for cases of a large temperature difference between the liquid inside solar collector pipes and the ambient air.

It is interesting that trackers of such large solar stations cost several tens of dollars per sq. m, and this is only 10-20 % of the cost of a traditional solar collector, although small trackers can cost more than 100 $ / sq. m. So, it may seem to us that installing solar collectors on such trackers makes good economic sense for cases of a cheap tracker and if the cost of our solar collectors is more than 100 $ / sq. m. But we must understand that traditional trackers are designed for lightweight panels, and not for heavier solar collectors, and their summer effect is noticeably greater than in winter.

We know about such air solar heaters where solar radiation can heat air to almost 100 ºC. We also remember this solar collector from Finland, and it has this absorber for heating liquid. In addition, the Finnish collector has this fan for circulating ambient air through the space between the absorber and the glass sheet, and may be also through the space under the absorber.

So, we have the opportunity to connect the Finnish collector with an air solar heater which will heat air for its circulation through the Finnish collector. Obviously, the hot air will increase the efficiency of the Finnish collector because it will reduce heat losses from the collector through its glass sheet. In addition, the hot air can transfer heat from the air solar heater to the absorber of the Finnish collector.

The economic sense of this idea is based on the fact that our solar collector is many times more expensive than the air solar heater which increases the efficiency of our collector by several tens of percent.

Now I will show four of my experiments which measure the efficiency of this simpler version of our idea, but without the fan. This part is our solar air heater, and this part is our solar collector which uses this polymer absorber to heat water.

My first experiment measured the efficiency of this homemade solar collector where that absorber was covered with a transparent polyethylene film.

This is the first experiment when the collector heated 26 liters of water of this tank from 22 ºC to 69 ºC for 2 hours. One hour later, the temperature of those 26 liters increased to almost 79 ºC.