Talk:Benban Solar Park

Power, capacity and all that

I have tried to make some clarifications regarding power, annual production, plant factor etc. In case the statements are not clear enough I add some further clarification. According to the article Solar irradiance the "maximum normal surface irradiance ... is approximately 1000 W /m2 at sea level on a clear day.". This is the insolation at noon, with no clouds etc. Should the sun shine both day and night (!), no clouds and so on, this would correspond to an annual insolaton of 8760hr*1000W/m2 = 8760 kWh/(m2,yr). Obviously the annual insolation can never be higher than 50% of this because it is night 50% of the time, and in addition there are clouds, morning and evening. The annual insolation for a certain site hence depends on weather, latitude, height above sea etc, and is normally reported as kWh/(m2,yr). Typical values are 1000 for Sweden, UK, 2000 for Spain, Italy, and the most extreme value I have seen is in Chile in the Atacama-desert where due to the high height above the sea level and the very dry climate insolation can be as high as 3000 kWh/m2,yr). In this case for Benban solar park it can be found in the Environmental & social assessment report (ref 1) on page 46 (pdf-page 56) a diagram with monthly radiation. Through a careful interpretation of this diagram I summed up the irradiation to appr 2300 kWh/(m2,yr). This means that if you have a PV-panel (regardless of size or efficiency) that gives say 1000 W at noon on a clear day (assuming normal efficiency of about 15% for commercial PV-panels this would require a panel of about 7 m2), it would theoretically give 8760 kWh/yr if the sun was "shining at noon all the time", but as this is not the case it will give (2300/8760)*1000W = 2300 kWh/yr or approximately 26% (2300/8760) of the peak power (or name-plate capacity). Here are several simplifications, but anyhow I think it is important to clarify that a "capacity" of 752 MW does not mean that this power is delivered all the time. It is delivered at noon, when there are no clouds, and approximately the average power will be 26% of this.