Solar Panels and Diffuse Light

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MikeAqua

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#207780 13-Jan-2017 13:07

I want to install a solar panel inside a boat shed. The purpose is to keep a 12V battery topped up while devices draw standby current.

I don't own the building there is no mains electricity available and I'm not allowed to install a panel on the outside.

So my plan is to buy a solar panel I can plug into the 24 hour circuit on the boat, while it's parked up and remove when I take the boat out.

The total draw I need to replace is less than 1AHr/Day. Battery used for standby is 12AH Lithium Iron type with built in battery management.

There is indirect/diffuse sunlight in the shed from translucent plastic panels in the roof. The roof gets all day sun.

Is this likely to be feasible at all?

If the light is diffuse is the optimum mounting angle horizontal?

Mike

neb

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#1702792 13-Jan-2017 16:18

That's going to be quite difficult to answer without knowing the composition and effect of the diffuser, what you'd need to do is get some cheap solar-powered whatsit and charge it outside and inside under the diffuser to estimate what overall effect it's having. You could also try measuring the intensity of the light if you can borrow the right gear, I've got a weather station that provides a readout in W/m^2 but it's not terribly portable. A cheapie Aliexpress meter may not give anything like a valid reading, but it should be able to provide the ratio between raw and filtered light.

timmmay

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#1702800 13-Jan-2017 16:30

I think neb's right, you'll have to try it and see. If you can put the solar panel close to the diffuser you'd probably do better, but if it lights the whole shed quite well it might be a bit of a challenge.

I have a solar panel in a window, it works ok. If I ever really need more power I just carry it outside using the extension cord I had made up for it.

neb

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#1702915 13-Jan-2017 21:47

Just did a quick search, you can now get a pretty decent wide-spectrum sensor with I2C interface for under ten dollars, which was pretty unheard of just a few years ago. This device claims to cover from IR through to UV, with a standard I2C interface so you can connect it to an Arduino or Pi or whatever. You can get the same thing from Adafruit for the same price (given USD, + shipping to NZ). Data sheet is here.

raytaylor

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#1703284 14-Jan-2017 20:38

You would need a bigger panel than those little top-up ones that super cheap auto sell - eg. 60 watts.

But that means you would need a solar controller. You are best to talk to a solar for outdoors/camping specialist solution supplier.

Our local one is cellpower - in auckland there is AASolar (though they have less specialty in marine)

Ray Taylor

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