Do Solar Panels work on a Cloudy Day.

DATE: Mar, 3   COMMENTS: 0   AUTHOR: Allan Azarola

There is currently a big push to roll out solar panels in Ireland. The Irish weather is not known for its sunshine, quite the opposite in fact.  Ireland is not what you would call a sun holiday destination. So with the big push in solar panels been driven by the Government and taking into consideration the Irish weather it is reasonable to ask the question, do solar panels work on a cloudy day.  Are they any good for Ireland?

The answer is Yes.  A cloudy day will reduce the efficiency of your panels, they will not generate as much electricity however it will not cause them to stop working.

According to the Environmental and Energy Study Institute (EESI), even in only partly cloudy weather, solar photovoltaic ( pv)  cells can still operate at upto 80% of their maximum output. How is this I hear you say, well this  is due to the fact that solar solar panels need daylight (‘diffuse’ light) and not sunlight (‘direct’ light).

This now begs the question; how much actuly energy can my solar system generate during a cloudy day?  Is it still worth it This is the question that most people in Ireland who are planning or thinking of buying solar panels will ask as they research their buying options. The Irish climate is unpredictable at the best of times so this is very much a valid concern. The answer is – much more than you think. 

The graph below shows daily irradiance for a day in June, in Dublin the capital city of Ireland. It clearly shows how solar irradiance maxes out at midday, the ability for the most solar PV generation occurs at this time. The amount of irradiance depends on factors such as cloud cover present or a clear sky. The orange line marked ‘diffuse’ depicts the amount of solar irradiance on a cloudy day, whereas the blue ‘clearsky’ line illustrates the level of solar irradiance on a day with no clouds present in the sky. 

How Do Solar Panels Work? 

The purpose of a solar panel system is to absorb sunlight, also known as photovoltaic energy (PV), and convert it to direct current (DC) power. The key components to solar panels are called photovoltaic cells. Each individual PV panel contains a number of these cells, which are all sandwiched between two layers of semi-conducting material. These cells absorb photons by gathering light provided by the sun.  

So Why Do Solar PV Panels Still Work on Cloudy Days? 

You now know how solar panels work,  the key takeaway from this is that solar PV panels can harness both daylight (‘diffuse light’) and sunlight (‘direct light’).  

Solar panels will not operate at maximum production when clouds are blocking the sun. However, anyone who looked up and seen the clouds and so not bothered with sunscreen but still has gotten sunburned on a cloudy day knows that solar radiation can and does penetrate clouds. For that same reason, solar panels can still produce electricity on cloudy days.  

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