Best use of excess Solar

DIY
1

I have a barn which I use of storage. The barn is very old and is 9" solid walls, slate roof and has no insulation and is very damp (had 20 years of leaks which are now sorted)

Ive 1.5kw of solar installed and a 480ah battery bank.

Daily requirement is 150wh

What are the best uses of excess solar to help dry out the barn?

Currently have a 12V ceiling fans coming on at 13v and also a car radiator fan in a window at 13.8v, but as the sun get stronger will have a far lot more energy going to waste.

Ive thought of a 12v water heater and plumbing up a radiator and pump?, or more fans?

A dehumidifer is a thought, but running an inverter will result in large current draw and being the building is not well insulated would be pointless, If I could get the same hummidity as outside, I would be happy?

Im guessing at 12v, air changes are going to be the best way of drying, so large fans drawing air in downstairs and pushing out upstairs are the best options?

Any advice or ideas appreciated

2

Through natural heating the air up high will be warmer than the air at ground level, so I’d say try circulation of the warmer air high up would benefit.
When external temps warm up get as much air flow in / out

3

Which voltage?

Better than warming the barn would be cooling it. Use an ordinary air conditioner to cool the barn, and by doing that, the a.c. will remove plenty of humidity from the air.