Derating. How does that work?

[Bobster.]

So it's getting near mid day, my solar panels are pumping 3+ kw. Then the battery gets to 100% SOC and the electronics in the system "derate" the panels and now there's just a small output to service any loads and keep the batteries topped up.

But the sun is still shining just as brightly, and the panels themselves must be producing as much energy. So where does it all go? Is there some big heat sink somewhere?
 

[NigelL]

Hi Bobster

While your solar panels are capable of generating 3kW - they only deliver the amount of power that is required by your system. Practically, this is done by your solar charger limiting the amount of current drawn from the solar panels.

Sunlight energy on solar panels is normally converted into a small amount of electrical energy (e.g. 17%) and the remaining power (83%) is dissipated as heat. When you stop drawing electrical energy from the solar panel, 100% of the sunlight energy will dissipated as heat.

So you are correct - the solar panels are one very large heatsink  

Edited November 9, 2020 by NigelL

[Bobster.]

2 hours ago, NigelL said:

Hi Bobster

While your solar panels are capable of generating 3kW - they only deliver the amount of power that is required by your system. Practically, this is done by your solar charger limiting the amount of current drawn from the solar panels.

Sunlight energy on solar panels is normally converted into a small amount of electrical energy (e.g. 17%) and the remaining power (83%) is dissipated as heat. When you stop drawing electrical energy from the solar panel, 100% of the sunlight energy will dissipated as heat.

So you are correct - the solar panels are one very large heatsink  

Ah thanks.

[NigelL]

This results in a somewhat unexpected consequence - your solar panels will run slightly cooler as one draws more electrical power from them.

See https://www.sciencedirect.com/science/article/pii/S2211379716301280

Edited November 9, 2020 by NigelL