Solar panel on roof

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printmonkey
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Re: Solar panel on roof

Post by printmonkey »

Lights yes, but not a coolbox unless it's a compressor fridge ie Engel, Waeco, ARB etc.
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gypo
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Re: Solar panel on roof

Post by gypo »

printmonkey wrote:Lights yes, but not a coolbox unless it's a compressor fridge ie Engel, Waeco, ARB etc.
Ok thanks, Ive just ordered them so hopefully they shouldn't be too long :)
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Re: Solar panel on roof

Post by ghost123uk »

gypo wrote: Will I be pretty much self sufficient on 80w?
Mine is only 60 Watts and I find it does me OK, but only if it's a sunny day.


gypo wrote: will it [80W] run a cool box and my led lights?
Just so you know, most "ordinary" cool boxes use about 8 Amps of power, that works out at around 96 Watts ( 8A x 12V = 96W)
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Re: Solar panel on roof

Post by gypo »

Cheers buddy, I've ordered 1 x 50w and 1 x 20w so 70w in total it was the only way I could fit them on the van. I could probably get another 20w one in there but it's already cost me £250 :(
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Re: Solar panel on roof

Post by gypo »

Would I have to use the load out on the controller as all my load is already sorted via the zig charger I assume. So is the load out in the controller redundant
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G
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California Dreamin
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Re: Solar panel on roof

Post by California Dreamin »

Hi mate....I'm in the same boat as you on this...it would be quite complicated to rewire in order to route the 'outgoing consumers' through this 'load' circuit...I am assuming (and I can't see any reason not to believe this) that leaving this circuit redundant won't have any effect other than the load circuit will always read zero....although it would be NICE to see the balance between 'what is going in' compared to 'what is going out'.
Anyone know otherwise?

Martin
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gypo
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Re: Solar panel on roof

Post by gypo »

California Dreamin wrote:Hi mate....I'm in the same boat as you on this...it would be quite complicated to rewire in order to route the 'outgoing consumers' through this 'load' circuit...I am assuming (and I can't see any reason not to believe this) that leaving this circuit redundant won't have any effect other than the load circuit will always read zero....although it would be NICE to see the balance between 'what is going in' compared to 'what is going out'.
Anyone know otherwise?

Martin
This is my thoughts exactly, I can't see a problem (unless I'm corrected) other than the load reading zero.
G
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phil_b
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Re: Solar panel on roof

Post by phil_b »

Hi, similar to you due to space restrictions I have fitted 2 x 50w panels rather than one bigger panel, no performance downside that I can see. Charger controller connected directly to leisure battery not through zig unit and load connection not used as mine had max output of 10amps. Has been working great for last 18 months, will also charge the main battery if you switch zig to touring rather than on site.
You should take care in your panel positioning as you have mentioned a roof rack, even a small amount of shadow from this will have a disproportionate effect on panel output, something like 10% shadow will reduce output by 75% or more.
We have been very pleased with our setup which allows us to wildcamp for extended periods without the need to charge by driving.
Cheers phil
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Re: Solar panel on roof

Post by gypo »

Many thanks Phil for the reply
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Re: Solar panel on roof

Post by ghost123uk »

Hi Phil, not disputing you at all as I simply don't know, but

phil_b wrote: even a small amount of shadow from this will have a disproportionate effect on panel output, something like 10% shadow will reduce output by 75% or more.

I wonder why that is ?
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CJH
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Re: Solar panel on roof

Post by CJH »

ghost123uk wrote:Hi Phil, not disputing you at all as I simply don't know, but

phil_b wrote: even a small amount of shadow from this will have a disproportionate effect on panel output, something like 10% shadow will reduce output by 75% or more.

I wonder why that is ?

I've heard this too, from a friend who uses one on a boat, where masts and the like cause a lot of partial shadowing problems. Something to do with the cells being 'current sources' rather than 'voltage sources' perhaps. I'm no expert, but I read the following here.

The lowest solar cell current is the output current of the PV panel and the surplus current of each solar cell flows back through its diode.
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Oldiebut goodie
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Re: Solar panel on roof

Post by Oldiebut goodie »

California Dreamin wrote:Hi mate....I'm in the same boat as you on this...it would be quite complicated to rewire in order to route the 'outgoing consumers' through this 'load' circuit...I am assuming (and I can't see any reason not to believe this) that leaving this circuit redundant won't have any effect other than the load circuit will always read zero....although it would be NICE to see the balance between 'what is going in' compared to 'what is going out'.
Anyone know otherwise?

Martin
I've got one sitting on my table that I was going to use for testing - my thoughts were to use the load terminals as a LVD device switching a relay to cut out all the leisure electrics when the voltage dropped too low. I have just got to get around to setting it up to see how well it would work.
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phil_b
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Re: Solar panel on roof

Post by phil_b »

Lots of info on the internet about the impact of shade on panels, but the easier for me to understand was that each cell in a panel can be thought of as a valve which is open to flow current when sunlight falls on it and closed when in shade. As panels are generally made up of a number of cells arranged in series like a long pipeline, shade on just one in that series closes the valve and effects flow in the whole series. The more separate series of cells in a panel or separate panels, each with a blocking or bypass diode, the less the impact of shade on the whole.

Probably a massive over simplification but helped me get my head around the impact of shade if not the science.

Cheers Phil
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djburns
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Re: Solar panel on roof

Post by djburns »

Can vouch for the problems of shading. Just come back from Cornwall. I have an 80w fold out panel which links through a controller direct to the leisure battery. Sunny interval type days keep things charged to run a waeco fridge, led lights, water pump etc. but NOT IF A GERMAN MOTORHOME THE SIZE OF A BLOCK OF FLATS WITH A DOZEN SURF BOARDS ON TOP PARKS NEXT TO YOU AND PUTS YOU IN PERMANENT SHADOW!
I also find if you are around the van it helps to just keep turning the panel to face the sun. Lying flat on top of the van reduced the charging rate. I am thinking of a flexi 100w panel to put on top of a large roof box I use on longer trips.
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