How to estimate PV power generation?

2022-03-18

How to estimate PV power generation?

To set up an off-grid PV system, the main components are solar panels, solar charge controllers, solar inverters and batteries. Before building a PV power generation system, it is necessary to estimate the power output of the PV system. Only by doing a correct estimate can the PV system be used more reasonably in life.

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This work is usually calculated and analyzed based on factors such as the annual amount of local solar radiation and the efficiency of PV power plants.

We can start by looking at the formula for theoretically calculating PV generation:

E=H*Pe*K

E -- Generating capacity of PV power station (kWh)

H -- Solar peak hour on PV module surface (H)

Pe -- Total installed PV (kWp)

K -- System comprehensive efficiency factor (%)

For example:

For example, the total PV installation (Pe) is 1kWp

The solar peak hour (H) of the PV module surface is 4.5h in a day

The overall efficiency factor (K) of the system is 80%

The daily power generation is about E=H*Pe*K=1*4.5*0.8=3.6kWh

How do you know the solar peak in your area? There is a one-size-fits-all solution, and that is to use GOOGLE search. Hahaha.

Using the above method, you can get a rough idea of your PV system's theoretical output per day.

However, with the increase of the life of the PV system, the PV system components will certainly decay. According to the data statistics, the attenuation of the PV system can be referred to the following table:

Year	Component attenuation（％）
1	0
2	2.0
3	0.8
4	0.8
5	0.8
6	0.7
7	0.7
8	0.7
9	0.7
10	0.7
11	0.6
12	0.6
13	0.6
14	0.6
15	0.6

The decay rate of components increases successively every year, for example, the decay rate of the fifth year is 0+2+0.8+0.8+0.8= 4.4%

Then in the fifth year, the daily power generation is E=H*Pe*K* (1-decay rate) =1*4.5*0.8* (1-4.4%) = 3.44kwh

Conclusion

To measure the quality of a PV system, power generation efficiency and capacity are very important indicators. A correct assessment of power generation can not only predict the benefits of the PV system, but also understand the operating status of the PV system, providing a scientific basis for the operation and maintenance of the PV system.