Solar panels

Jun 18, 2008
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Hi,i am looking for a solar panel to charge my batteries whilst away for 2 weeks. We only go on DA's so we do not use electric hookups.Two batteries are good enough for a weekend but we will struggle for longer.

TV , hair straighteners,hairdryers etc etc are used so will need 40w + .Looked at loads but still undescided.Any help on price & technical greatly appreciated.

Thanks Terry.
 
Nov 4, 2004
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The Steca PR1010 will only measure a load output from the regulator not what ampage you are using from from the caravan battery,there are some 12v battery monitors on the market which are used in the marine industry which show battery usage in amps and how much it is being charged.
 
Feb 28, 2009
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The Steca PR1010 will only measure a load output from the regulator not what ampage you are using from from the caravan battery,there are some 12v battery monitors on the market which are used in the marine industry which show battery usage in amps and how much it is being charged.
I did say through the unit !
 
Jan 26, 2008
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You need to measure the load you are using on your system. Once you've done that you'll be able to work out the right size of panel.

A 40w panel doesn't sound like enough for what you are suggesting.

There is a web site that allows you to work out exactly what size solar panel you need. Go to www.SolarElectricityHandbook/solar-calculator.html and go to the Project Analysis section. You can then enter the appliances you are planning to run, their power consumption and estimated number of hours of use.

Based on the information you give it, it will then send you an 11 page report with exactly what you need in terms of panels, controllers and so on.
 

JTQ

May 7, 2005
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Playing with some figures; if that helps you:

You say two batteries last you a week end but struggle for longer.

Say your two batteries last three days, are each 85 watts and you deplete them to 25%. Then your using about 42.5 amp hours per day. Note I am being conservative in taking three days and not assuming larger batteries.

A 40 watt solar cell yielding 50% capacity for say 6 hours a day and 25% for another 6 hours a day, will give you 10 + 5 = 15 AH.

This is not unrealistic for UK summer time and will fall sharply in other seasons [lower sun angles plus shorter time plus higher incidence of grey days]

Your nett short fall would be 42.5 -15 = 27.5 AH per day; thus your two batteries available capacity of 128Ah would extend your period to about 4.5 days; only another day and a half.

Your usage is I suggest far too high to be considering a 40 Watt panel.

I use an 85 watt panel; if you went to that size the numbers would improve to:

Yield; 31.875AH per day. Nett short fall 42.5 - 31.875 = 10.625

Period to drain your 128Ah capacity: 128/10.625 = 12days. You could be confident of a week away in the summer unless the weather was really cruel.

So you either need to address your usage or think bigger solar cell.

Cheers John
 
Jan 18, 2008
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Playing with some figures; if that helps you:

You say two batteries last you a week end but struggle for longer.

Say your two batteries last three days, are each 85 watts and you deplete them to 25%. Then your using about 42.5 amp hours per day. Note I am being conservative in taking three days and not assuming larger batteries.

A 40 watt solar cell yielding 50% capacity for say 6 hours a day and 25% for another 6 hours a day, will give you 10 + 5 = 15 AH.

This is not unrealistic for UK summer time and will fall sharply in other seasons [lower sun angles plus shorter time plus higher incidence of grey days]

Your nett short fall would be 42.5 -15 = 27.5 AH per day; thus your two batteries available capacity of 128Ah would extend your period to about 4.5 days; only another day and a half.

Your usage is I suggest far too high to be considering a 40 Watt panel.

I use an 85 watt panel; if you went to that size the numbers would improve to:

Yield; 31.875AH per day. Nett short fall 42.5 - 31.875 = 10.625

Period to drain your 128Ah capacity: 128/10.625 = 12days. You could be confident of a week away in the summer unless the weather was really cruel.

So you either need to address your usage or think bigger solar cell.

Cheers John
Terry.

Got my solar panel fitted at one of the shows by detroit solar i was very pleased with the work they did so if i was you look at this company for you solar as they are very helpful.
 
Jan 18, 2008
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If you are looking for a solar panel for youe needs i would have one off detroit solar they fitted one for me and i am very happy with the work they did so give them a call .
 
Feb 28, 2009
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Chris,

I fitted my solar system myself but have not permanently fitted the panel to the roof. This b****y new infamous Swift Conqueror van has so many problems that I am likely to tow it to the factory, call the press and set fire to it!!

But what I have done seems to work well. I fitted the PR1010 in the overhead locker by the sun roof. I fitted non slip pads to the panel brackets and attached a 3 pin (lawnmower type) connector to a short cable to the panel. Matching connector wired to the Controller. All I have to do is open the sun roof and put the panel on the roof. Bring the cable over the roof locker and plug together. The Swift lockers have a gap at the top that the cable goes over. The sun roof can be shut on the ventilation catch without crushing the cable.

The panel appears to be quite stable thanks to the non slip pads.

A 3 pin connector makes polarity reversal impossible

The panel fits in the table locker when not in use. All works very well.

The system is an easy DIY fit.

Hope this makes sense, any questions, just ask.

Jim
 
Jun 18, 2008
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You need to measure the load you are using on your system. Once you've done that you'll be able to work out the right size of panel.

A 40w panel doesn't sound like enough for what you are suggesting.

There is a web site that allows you to work out exactly what size solar panel you need. Go to www.SolarElectricityHandbook/solar-calculator.html and go to the Project Analysis section. You can then enter the appliances you are planning to run, their power consumption and estimated number of hours of use.

Based on the information you give it, it will then send you an 11 page report with exactly what you need in terms of panels, controllers and so on.
Thanks...just got back from long weekend....definately need to sort out this issue...having a look at the site before i fall asleep...Terry
 
Jun 18, 2008
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Playing with some figures; if that helps you:

You say two batteries last you a week end but struggle for longer.

Say your two batteries last three days, are each 85 watts and you deplete them to 25%. Then your using about 42.5 amp hours per day. Note I am being conservative in taking three days and not assuming larger batteries.

A 40 watt solar cell yielding 50% capacity for say 6 hours a day and 25% for another 6 hours a day, will give you 10 + 5 = 15 AH.

This is not unrealistic for UK summer time and will fall sharply in other seasons [lower sun angles plus shorter time plus higher incidence of grey days]

Your nett short fall would be 42.5 -15 = 27.5 AH per day; thus your two batteries available capacity of 128Ah would extend your period to about 4.5 days; only another day and a half.

Your usage is I suggest far too high to be considering a 40 Watt panel.

I use an 85 watt panel; if you went to that size the numbers would improve to:

Yield; 31.875AH per day. Nett short fall 42.5 - 31.875 = 10.625

Period to drain your 128Ah capacity: 128/10.625 = 12days. You could be confident of a week away in the summer unless the weather was really cruel.

So you either need to address your usage or think bigger solar cell.

Cheers John
Hi,called in at a dealer whilst away & they told me of a monochrystal type that charges on "grey" days just as good as "sunny" ones...Do you think this is just salesmanship..I am just spinning around confused ..I thought this would be an easy purchase but obviously not...have one week to decide ! Generator option is becoming more viable...Terry
 
Jun 18, 2008
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If you are looking for a solar panel for youe needs i would have one off detroit solar they fitted one for me and i am very happy with the work they did so give them a call .
Hi, will have a look tomorrow,a good recomendation is better than a bad guess....Thanks Terry
 

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