How to increase the efficiency of photovoltaic panels?

Developed based on product cards of LONGi LR4-72HPH modules

Such parameters are usually checked in laboratory conditions to give the most precise results and thus the best approximation of the efficiency of PV panels in converting solar energy into electricity.

Efficiency of photovoltaic cells during the year

The highest efficiency of a photovoltaic installation is from May to September, i.e. in the months when roofing felt and sheet metal roofs heat up the most . It is worth noting that the peak efficiency of photovoltaic panels takes place in the summer months: June, July, August.

This means that in reality our photovoltaic installation may bring much lower profits than we expected , because the payback period is usually calculated for laboratory conditions, which do not take into account the temperatures to which the roofing felt or sheet metal can heat up.

We can say that covering a roof with felt or sheet metal does not ensure optimal photovoltaic efficiency .

The solution in such a situation may be a light-reflecting membrane , which allows you to reduce the roof temperature to 42 degrees C, and thus increase the efficiency of photovoltaic panels.

Ways to renovate the roof for photovoltaic panels

In the case of roofs made of thermally weldable felt, a common solution is to apply a second layer of felt on the damaged roofing. This solution carries some risk related to roof load.

It is worth paying attention to the weight of the material. 1 m2 of roofing felt weighs approximately 6-7 kg. Applying a second layer of roofing felt during renovation gives us a double load, but we also have to take into account the photovoltaic panels themselves, which also load the roof (the installation system together with the panels is in the range of 18-25 kg/m2).

This is a significant load on the roof and may overload the entire structure. The solution to these concerns may be a light-reflecting membrane.

The weight of such a membrane is 1.5 - 2.5 kg/m2, which significantly reduces the risk of overloading the roof, and additionally, the use of a white membrane contributes to increasing the efficiency of photovoltaic panels.

Advantages of light-reflecting membranes over roofing felt: 

Waterproofing, polyurea liquid membranes have many advantages over the bituminous roofing felt we have known for years. It is definitely worth taking them into account when planning roof renovation or terrace waterproofing.  

Ease and tightness of processing

Bituminous felt roofing always has many joints and requires very precise processing around chimneys or skylights on the roof. These places are usually the first to start leaking. These leaks are very difficult to locate because the water may find its way out in a place far from the leak.  

Liquid waterproofing membranes, such as Neoproof PU W-40 or Neoproof Polyurea R, create a homogeneous, continuous coating on the roof, without any joints. A "tight bathtub" is created and the risk of leaks in critical points is minimized to virtually zero.  

Easy repairs 

The need to carry out minor renovations is unlikely to occur very quickly, but if it does arise, it will only involve local repainting. We do not need any additional special equipment. All you need is a paint roller.  

Easier removal of snow from the roof/no snow accumulation

Due to the lack of absorption, snow does not stick to polyurea. When snow covers our solar panels, energy production drops to zero. This is especially important if the photovoltaic panels are mounted on a roof/supporting structure with a very small angle of inclination. They must then be cleared of snow, because otherwise the zero efficiency of photovoltaic panels may last even until spring (until the snow melts and electricity production can be resumed).  

Reflecting light

Being aware of the loss in efficiency of photovoltaic panels that results from the roof covering heating up to high temperatures, it is worth considering solutions that will better cope with weather conditions. Thanks to this, not only will our photovoltaic installation not lose efficiency, but the efficiency of the panels will also increase thanks to the reflection of sunlight (up to 88% when using Neoroof), which the photovoltaic modules will also be able to receive.  

Better efficiency of photovoltaic panels and faster payback period - this is how the main advantages of using light-reflecting membranes on roofs intended for mounting photovoltaic panels can be summarized.  

Before deciding to invest in solar panels, it is worth answering the question whether we have taken a closer look at all the factors that determine the profitability of this project?