How to increase the efficiency of photovoltaic panels?

Development based on the product cards of the LONGi LR4-72HPH modules

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

Photovoltaic cell efficiency per year

The highest efficiency of a photovoltaic installation occurs from May to September, the months when roofing felt and sheet metal roofs heat up the most . It's worth noting that the peak efficiency of photovoltaic panels occurs during the summer months: June, July, and 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 roofing made of felt or sheet metal does not ensure optimal photovoltaic performance .

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

Roof renovation methods for photovoltaic panels

For roofs made of heat-sealed felt, a common solution is to apply a second layer of felt over the damaged roof covering. This approach carries a certain risk of roof loading.

It's worth considering the weight of the material itself. 1 m² of felt weighs approximately 6-7 kg. Applying a second layer of felt during renovations doubles the load, but you also need to consider the photovoltaic panels themselves, which also add weight to the roof (the mounting system, including the panels, weighs 18-25 kg/m²).

This is a significant load on the roof, which can overload the entire structure. A reflective membrane may provide a solution to these concerns.

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 reflective membranes over roofing felt: 

Liquid polyurea waterproofing membranes offer many advantages over the long-established bituminous felt. They are definitely worth considering when planning a roof renovation or terrace waterproofing. 

Ease and tightness of machining

Bituminous felt roofing always has many joints and requires very precise work around chimneys and skylights. These areas are usually the first to develop leaks. These leaks are very difficult to pinpoint because the water may find its way out at a point far from the leak. 

Liquid waterproofing membranes, such as Neoproof PU W-40 or Neoproof Polyurea R, create a uniform, continuous coating on the roof, without any joints. This creates a "sealed bathtub," minimizing the risk of leaks at critical points to virtually zero. 

Easy repairs 

Minor renovations aren't likely to be necessary anytime soon, but if they do arise, they'll simply require a spot repaint. No additional special equipment is needed. A paint roller will suffice. 

Easier snow removal from the roof/no snow build-up

Due to its lack of absorption, snow doesn't adhere to polyurea. When snow covers our solar panels, energy production drops to zero. This is especially important if the solar panels are mounted on a roof/support structure with a very shallow angle. Snow must be cleared from the roof or support structure, otherwise, the solar panels' zero efficiency could last until spring (until the snow melts and electricity production can resume). 

Reflecting light

Given the loss of efficiency in photovoltaic panels resulting from roofing heating to high temperatures, it's worth considering solutions that better cope with weather conditions. This not only ensures our photovoltaic installation won't lose performance, but also increases panel efficiency by reflecting solar radiation (up to 88% with Neoroof), which the photovoltaic modules can then absorb. 

Better efficiency of photovoltaic panels and a faster payback period – these are the main advantages of using reflective membranes on roofs intended for the installation of photovoltaic panels.  

Before making a decision to invest in solar panels, it is worth answering the question: have we considered all the factors that determine the profitability of this project?