Did someone mention winter?

[Rolfe]

That's interesting.

 

[T1 Terry]

I have measured close to 100°C on the underside of solar panels over here in the full summer sun.
It was a common complaint over here regarding solar not working during the day between about 10am and 4pm in mid-summer and became an accepted fact for caravans and motorhomes. The problem was, the Vmp (Voltage Maximum Power) would drop below battery voltage using 12 V nom. panels to charge a 12 V lead acid battery.

Early MPPT controllers were very inefficient, unless you paid mega $$ for the likes of a MidNite solar controller, but they also have a function that can boost battery power to the solar array voltage and turn the panels into heaters to remove a snow load .... there is every possibility MPPT controllers for grid tie systems have adopted the same idea .....

There was a company that developed wet backed solar panels to stabilise the panel and double as a solar water heater .... the cost and complexity of connecting them was quite possibly their downfall, I haven't heard mention of them for quite some time ....

T1 Terry