Solar module, also known as solar panel, is an assembly of silicon cells (solar cells), designed to convert light energy into electric energy.
Since each cell has a capacity of 4-5W only, they are combined into solar panels with total capacity from 10W to 400W. Solar power plants are typically using 280-370W panels because of their ease of handling and production cost.
Solar cell efficiency is an important parameter of a panel. For the last 40 years, researchers in different countries across the world have been striving to maximize the efficiency of solar energy conversion. Cells with efficiency at 44% were reported, but unfortunately those were only prototypes and their cost is too high for common use.
Currently (in 2019) the standard efficiency of solar modules is at 15-21% depending on solar panel type. The following panel types are mostly offered in the market:
- Monocrystalline solar panels with 18-21% efficiency;
- Polycrystalline solar panels with 15-18% efficiency;
- Thin-film solar cells (based on amorphous silicon) with 6-9% efficiency.
In general, monocrystalline and polycrystalline solar panels are very similar in terms of technology and efficiency. However the production cost of polycrystalline panels is some 10-15% lower, which makes them more favorable for large systems, where energy cost makes difference.
It is notable that single-crystal shows better performance when exposed to direct light. Therefore it proved efficient in dry and hot climates in such regions as Africa, Middle East, and countries like Mexico, Australia, etc. In contrast, polycrystal is better than single-crystal in deffused lighting and is more preferable for countries with moderate climate, where the sky is often overcast.
As for thin-film solar cells, their performance has been disappointing in recent years. Despite low production cost, most global producers are currently discontinuing the production of these types of cells, though initially it was seen as quite promising technology. This reflects the fact that with only 6%-8% efficiency these cells lose 20%-40% of their capacity in the first 2 years of operation. This results in a cumbersome and inefficient system. Total power generation cost turns out to be significantly higher than expected and the project becomes a poor investment.
In general, solar modules are quite durable, reliable and easy to install. Any competent tradesman can also install solar panels. They can be used in any climate – in the rain or snow, at +50C and -80C, they will serve you well for at least 30~40 years.