Weather conditions have a huge influence on photovoltaic output. Even intermittent cloud cover can have a dramatic effect on incident solar energy, while other factors like air temperature, wind direction and speed, precipitation, humidity, and air pressure can all influence the efficiency of solar cells. Monitoring weather conditions accurately is crucial to understand variations in PV plant performance.
While variations in weather conditions may be of only passing concern to the average domestic PV user, they are of critical importance for commercial and industrial PV systems.
For large installations, even small relative fluctuations in performance can make a huge difference to overall productivity, and any source of output variation must be closely monitored to ensure the overall system is performing optimally.
In these cases, meteorological monitoring is essential to determine whether variations in output are due to weather conditions, or indicative of more serious hardware degradation or malfunction.
Weather monitoring is, therefore, an essential part of understanding PV system health and scheduling maintenance on time. Analysis of historical data – on precipitation and wind conditions, for example – enables seasonal trends to be uncovered, which can in turn be used to optimize cleaning and maintenance schedules on a seasonal basis.
Which weather parameters are important for solar PV?
Solar irradiance
Measurements of solar irradiance are crucial to determine the efficiency of a solar plant. This is usually expressed in terms of a performance radio (PR): the actual yield of the plant (how much energy it produces in a given time period) expressed as a percentage of its theoretical yield (how much energy it could produce in that time period assuming the panels convert the incident light into energy at their nominal efficiency).
