Solar panels

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TONYT25T25
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Solar panels

Post by TONYT25T25 »

Not an off grid person, but like to keep both my leisure battery and main battery charged by using a basic solar panel that just attaches to either one.  Been looking on line for these cheap ones for around £30 that come with a controller that comes with a USB output to charge mobile phones etc.  Has anybody had any experience with these either good or bad.  One thing i cannot see is how the Solar panel is connected to the controller and battery supplied with the package.
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Mocki
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Re: Solar panels

Post by Mocki »

I have no actual experience of these small panels , but Bearing in mind that a 100w solar panel will only produce 5amps at best in full sunshine , which is tickle charge .A 30w panel is going to maybe give you 2amps so only enough to maintain rather than charge 


 
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TONYT25T25
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Re: Solar panels

Post by TONYT25T25 »

Thanks, only looking at keeping the battery charged enough to maintain basic lighting, charge the mobile phone when required, even thought about buying one to use in the house, but just using an old battery with the panel just to charge the phones instead of plugging into the mains, looking at saving electricity. 
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Re: Solar panels

Post by lefty67 »

You'll be needin one of these
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TONYT25T25
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Re: Solar panels

Post by TONYT25T25 »

Funny you should say that, was looking at a wind generator converted from an old radiator fan, ie using the fan to generate electricity in the opposite direction if you know what I mean, with a bit of modification of course.
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Re: Solar panels

Post by Jeff J »

I have 2 old batteries & some LED lights in my lock up garage that has no power. I have one of the cheapo panels with crocodile clips that I use to swop between the two ( pair on the charger & pair on the lights ) had it like that for last 4 years & batteries have never gone flat.

TONYT25T25
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Re: Solar panels

Post by TONYT25T25 »

Similar idea that I was investigating, have a couple of old batteries also, which still charge up via a small Solar Panel I got from Halfords, saves throwing them away as they still retain the charge to some extent.  This is the type I was looking for information about to see if anybody has used these or similar.

80W Solar Panel Kit 18V Battery Charger Controller 30A For Car RV Caravan Boat | eBay
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Re: Solar panels

Post by Mocki »

There is no way that is a 80w panel .
less than a foot square , it’s more like 8w 
beware . 
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TONYT25T25
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Re: Solar panels

Post by TONYT25T25 »

Thanks, still researching these and others, trying to find some feedback and reviews on these and similar ones.
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Aidan
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Re: Solar panels

Post by Aidan »

I have a 20w in the windscreen of the van which is permanently parked up facing SE, and one of the £10 controllers and it does a great job of maintaining battery charge, and during the summer will actually replenish a little. The panel knocks out over 20V in full sunshine so without the controller is not really suitable for direct connection even though the Ebay ad said it didn't need a controller and it was supplied with a lead that had battery clamps fitted; I looked at loads on Ebay and choose the largest "20w" one with the best looking cells, fewest connections cell to cell and least hyperbolic description from a reputable UK seller, it has 4 eyelets so two suction hooks on the screen and most of the weight on the dash it stays put fine, only had to re-fix the cups once in 2 years. Connection to the controller is screw terminal/bare wire, I just cut the supplied cable and put the controller between the cell and the battery, USB charger charges the old phone I keep in the van as a bed time radio when needed. 

It's chucking it down at the moment so I am not about to go out there and take a photo, sorry

TONYT25T25
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Re: Solar panels

Post by TONYT25T25 »

I have read that any panel above 17/18watts a controller is recommended.  My existing one from Halfords is only 2.5W which I use to keep the battery topped up.  I have noticed that when I connect a meter directly to the panel it reads between 19 and 22v depending on sunshine, however when connected to the battery it just reads as normal IE 12.6v and increases accordingly depending on how long the sun shines showing that it is charging. So i am assuming that below 18watts a controller is not needed.  In the process at the moment trying to work out how to measure wattage from a solar panel, and do they draw power from the battery at night therefore draining it, believe a diode is somewhere in the line so looking on how this is actually working or can be tested.
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Re: Solar panels

Post by Aidan »

I tried mine without a controller initially (I got it in autumn) and battery voltage dropped noticeably overnight so I figured the diode alone (if there actually is one) wasn't enough, so I stumped up for the controller, I figured high summer over voltage might not be good for battery either. Battery has now lasted 3 winters without being otherwise charged and when called upon to start a vehicle has been ready

TONYT25T25
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Re: Solar panels

Post by TONYT25T25 »

Yes, I have been a bit suspicious of the claim that the panels do not discharge batteries over night because of a diode being fitted.  Need to explore a bit more I think, may buy one of the ones in the link just to try out and hope for the best.
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Re: Solar panels

Post by Stesaw »

I've just fit a 130w and the relevant controller bits onto our van the other day. Be nice to have alternate ways of keeping the leisure battery topped up as we found out in 2019 when it came to switching the lights on one night and nothing happened. Turned out the switch relay was dead and wasn't charging the leisure battery. 

Cutting a hole in the roof to feed the cables through did make me wince a bit. Also sealing a semi flexlible solar panel onto the roof wasn't as easy as I thought... :roll: .
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TONYT25T25
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Re: Solar panels

Post by TONYT25T25 »

Still researching and searching, couple of related posts by other members about routing cables including via the AC inlet connection and a redundant vent from an absorption fridge.
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