The highest temperature is 49℃! Photovoltaic power generation is making a fortune? Rumor!

Since May this year, India has suffered an unprecedented heat wave, with temperatures exceeding 45°C in many places. The capital New Delhi once recorded an extreme high temperature of 52.9°C. Although it was later confirmed to be a false alarm and the data was 3°C higher than the actual temperature, the temperature close to 50°C was enough to be fatal. At the same time, 14 people have died in Bihar, eastern India, due to high temperatures.

From New Delhi in Asia, to Bamako in Africa, to Mexico City and Las Vegas in America, many cities are scorching hot.

In extremely hot weather, it is not only the scorching sun that is difficult to overcome, but also the power supply shortage under the influence of high temperature. However, some people can't help but wonder, isn't high temperature a good time for photovoltaic power generation? Wouldn't photovoltaic power plants make a fortune?

I'm sorry, not only is it really hot this time, you are also really "naive".

Is it a good time for photovoltaic power generation on hot and sunny days?

The principle of photovoltaic power generation is essentially to use the photovoltaic effect generated by light irradiating semiconductors to convert light energy into electrical energy. Based on this, many people generally believe that hot weather with strong sunshine is more conducive to the power generation of photovoltaic equipment. The more sufficient the sunlight in hot weather, the more electricity can be produced.

However, high temperature does not mean more light energy.

Even the power of solar panels will decrease as the temperature rises. In other words, the higher the temperature, the lower the output power of photovoltaic modules.

In fact, the optimal power generation temperature of photovoltaic power stations is 23℃~24℃. When the temperature is 20℃, the normal working temperature of the module is around 45℃; under extreme high temperature conditions, the temperature of the module can be as high as 85℃, and the operating temperature of the internal battery may be higher.

Specifically, solar panels generally have three temperature coefficients, open circuit voltage, peak power and short circuit current. Taking peak power as an example, for every 1℃ increase in temperature, the power generation decreases by about 0.36%.

In addition, under high temperature, the open circuit voltage will also drop significantly, affecting the performance of the module. Studies have shown that the output power of the components is higher when the temperature is around 20℃ than when it is 70℃. Therefore, even if the light conditions are average, the power generation in low-temperature areas may be much higher than that in areas with strong light but high temperature.

As one of the main components of photovoltaic power generation, the working environment temperature of the photovoltaic inverter is relatively high, so the inverter is generally installed at a high place with shade and ventilation, and the solar inverter installed outdoors will be equipped with a sunshade cover, and the inverter must be kept ventilated.

Similarly, the components in the photovoltaic inverter also have a rated operating temperature. If the ambient temperature is too high, the temperature of the inverter will rise quickly when it is running at full power. When the operating temperature of the photovoltaic inverter exceeds the threshold, the output power will be limited, and even over-temperature standby protection will be triggered, which will accelerate the aging of the inverter components, affect the life of the photovoltaic power station, and increase the operation safety risk of the power station.

Simply put, high temperatures will significantly reduce the power generation efficiency of photovoltaic panels. If it is too hot, photovoltaic equipment cannot stand it.

High temperature can easily cause photovoltaic "heat stroke"

In addition, under high temperature, photovoltaic equipment will also produce hot spot effect and PID effect and other effects.

The hot spot effect refers to the fact that some components in the series branch are "shielded" for some reasons. Not only can they not generate electricity, but they will also be used as loads to consume the energy generated by other branches. Once a hot day occurs, the local temperature will be aggravated, strengthening the hot spot effect, directly leading to the aging and damage of the component panels.

As a "big board" exposed to the outdoors, it is inevitable that it will be contaminated, such as bird droppings, dust, etc. In normal times, bird droppings will cause a small resistance. Once high temperature occurs, it will aggravate the impact it brings, and it is very easy to burn out the components.

Like some rooftop distributed photovoltaics, hot spots cause local temperatures to rise rapidly, which can easily cause fire accidents. In recent years, fire accidents caused by hot spots have occurred from time to time. Timely maintenance and cleaning can largely avoid danger.

In addition, the PID effect (potential induced decay) will also be aggravated with high temperature and humid environment.

Since high temperature is often accompanied by humidity, taking the southeast coastal cities as an example, summer is accompanied by the plum rain season. A large amount of rain is accompanied by high temperature, making the entire air environment like a steamer. At this time, a large amount of water vapor in the air will enter the component through the edge sealing silicone or the back plate, causing a large amount of charge inside the component to accumulate on the surface of the battery cell, causing serious performance degradation.

Operation and maintenance guide for photovoltaic power stations under high temperatures

1. Cleaning photovoltaic modules is the key

Because photovoltaic equipment will produce hot spot effects under high temperatures, dust, bird droppings and other dirt are more likely to adhere to the surface of the modules under high temperatures, which not only affects the light reception effect, but also easily causes fires. Therefore, it is necessary to increase the frequency of cleaning, use a soft brush and clean water to clean, and try to ensure that the surface of the modules is as smooth as new.

2. It is important to keep the equipment ventilated

Photovoltaic modules, inverters, and distribution boxes must be ventilated to ensure air circulation.

Power station equipment is prone to heat, which affects the operating life and power generation efficiency. In the initial design, avoid mutual obstruction between modules, which affects heat dissipation and ventilation; in hot weather, regularly check the heat dissipation equipment to ensure its normal operation, and repair or replace it in time once a fault is found; in operation and maintenance, weeds and obstructions that affect heat dissipation should be cleared in time.

3. Shading of inverters and other equipment cannot be ignored

The inverter in the photovoltaic equipment has a high working environment temperature, so try to choose to install it in a cool place to prevent direct sunlight; if there is really no shade to install it, it is recommended to build a small shed.

4. Regular inspections are essential

There are many strong winds and thunderstorms in summer, which may cause damage or loosening of fixed structures.

Through inspections, you can understand the operation status of the power plant in real time, pay attention to data such as power generation and component temperature, adjust the operation strategy in time, and optimize the performance of the power plant.