Photo Cells to Turn Water Heater On to Use Solar Electricity

[paul10june]

I have solar electricity generation at home, and want to make better use of the electricity I generate by automatically turning an immersion heater on when light levels reach certain lux, and off when they fall below a certain lux.

There are plenty of on at dusk, off at dawn switches - typically used for security lighting

But I want an on at dawn, off at dusk version - preferably adjustable!

Can anyone help??

[redman41]

I'm sure something like this would suit your needs i.e connected between Immersion and Mains Fuse Box.

http://www.buy-electr...ion_Heater_Timer.html

[paul10june]

Thanks redman41 - the issue for me is making sure the water only switches on under bright light conditions. Its amazing how much electricity generation varies depending on light conditions...so i am still looking for that photo cell type device. Its strange they are readily available for the exact opposite of what i want!

[redman41]

The positioning of Photocell Timers would be important for obvious reasons, maybe on a dull day they would not work properly.
A lot would depend on where in the house your Immersion Tank is situated and how far from this would your Photocell Timer be located and would the location be ideal.
Might involve some rewiring and a lot of thought.

[AlBags]

I understand what you need Paul
A photocell is no good .. you need to test a few small solar recharge panels to see if the voltage can be used to switch at a voltage threshhold. This would have to be transistor based, I presume .. because of the low voltages.
Once you can find something that works (or stops working) at the required light level .. you are on the way.
Solar hot water arrays use a thermal sensor up in the gallery to signal the control panel. Can you not do something with that?