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OK.. So i have a difficult project...


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Hi all..  new to the forum..  I used to work with electronics back in the 80's.. was C&G 224 qualified but didn't stay in the profession so I've forgotten most of it!!

I'm ok with a soldering iron..  but don't really want to get to involved in making circuit boards...  breadboard maybe...  So I'm hoping I can get a little (lot) of help from you guys!

OK.. so here is my problem...  My house is powered completely by solar..   I have quite an extensive system so we live pretty normally...  but I'm trying to run a hot tub..

I have fitted a low wattage circulation motor (80w) so I can run that as long as I want..  but the heater is 1kw, so obviously I don't want that running all the time...  So..  I have fitted a 7m long solar water heating panel to take over the heating, and that is doing an amazing job...  But, I don't want the pump running at night because the black solar panel will remove the heat as quickly as it put it in during the day...

So, what I need is a switch circuit using a photocell to detect daylight, ....that needs to be adjustable..  i.e I don't want the pump to start to run at sunrise, only when it receives direct sunlight and therefore the panels will be getting direct sunlight... For instance I don't want the pump to run on cloudy days (not that we get many)...  get the picture?

The circuit would also need an override so that I can run it at night if we use the tub, which is fine as the pipework for the solar has a control valve so I can run the motor without the water going through the panels..

 

Any help would be much appreciated..

 

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Hi and welcome to the forum,

For what you describe you will need a light activated switch like this one: http://www.electronics-lab.com/project/light-and-dark-sensitive-switch/

This switch has adjustable sensitivity and with a little of experimentation you will manage to get the desired effect. It may be needed to add a kind of filter to the light sensor to reduce it's sensitivity even further as you need the switch to be activated in direct sunlight. You can also think to add a small "light pipe" to achieve the desired functionality.

Hope that helps.

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  • 2 months later...

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