Watt spike

[Rory Kilpatrick]

Please can someone explain, in layman terms how come yesterday, in East London on a partly cloudy day at noon my 10 X 550 watt panels produced 6800 watts [spike] as per Solis app. Solis 6kw inverter. 

 

[WannabeSolarSparky]

Cloud edge scatter affect.
Partly cloudy days scatter the suns rays more so you have light dropping onto the panels from more angles than just direct.

[TaliaB]

Like @WannabeSolarSparky said above just to add to that under certain meteorological conditions the solar insolation at ground level can exceed 1000 W/m². This can happen when sunlight scattered through clouds exceeds the amount of light(photons) normally contributed from clear blue sky. Unfortunately this normally only lasts a few seconds.

[Calvin]

3 hours ago, Rory Kilpatrick said:

Please can someone explain, in layman terms how come yesterday, in East London on a partly cloudy day at noon my 10 X 550 watt panels produced 6800 watts [spike] as per Solis app. Solis 6kw inverter. 

 

It is actually nothing to do with cloud edges, but it only happens when they are around.

An example: let's say that, at a time that direct sun yield would be 4.8kW, it is uniformly lightly cloudy and the light coming through the clouds gives you 2kW.

Now, imagine a small hole opens in the clouds that allows direct sunlight onto your panels, giving you the 4.8kW.  This does not materially affect the 2kW you get through the rest of the clouds, so your total yield will now be the sum of the 4.8kw and the 2kW = 6.8kW.

Edited September 7 by Calvin

[Rory Kilpatrick]

Thanks Guys.What I really don't understand is that it's 20% over the 550 watt rating . Doesn't  damage result from this ?  It's  almost like getting one liter of brandy from a 750 ml bottle 

[GreenFields]

3 hours ago, Rory Kilpatrick said:

Thanks Guys.What I really don't understand is that it's 20% over the 550 watt rating . Doesn't  damage result from this ?  It's  almost like getting one liter of brandy from a 750 ml bottle 

You should understand the Watt rating as the performance measured under a standardised set of test conditions in a laboratory. Using a standard amount of radiation, standard temperature, direct 90 degree angle of the rays, etc.

You might get better performance under special conditions like icy-cold temperatures, or reflecting extra light onto the panels with mirrors. Usually these conditions are temporary, or the design of the panels should factor it in because it's a known phenomenon, or they are mitigated for by the inverter, up to a point.