# Solar panel, help needed

Discussion in 'Motorhome Chat' started by Scattycat, Jun 10, 2014.

1. ### ScattycatFunster

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Our van is fitted with a 100w panel, but I'm not sure if it's working properly.
I've checked the calibration and it seems correct in as much as when it"s covered with a black cover it reads 0.00 amps.
I've checked the input from the panel at the regulator and it only ever shows 10.4 volts input and the best charge shown on the control panel is 1.5 amp with the battery showing a charge of 12.4 volts.
If I then plug into the mains the charge is showing at 16amps gradually reducing over about and hour to about 1.5 amps.
The lights on the solar control box shows that it is working correctly.
It's an 8 amp unit

Today, the sun has been strong all day and this morning the battery was showing 12.3 amps and the input from the panel was 0.5 amps.
No appliances were switched on and at the end of the day checking the battery and the panel the level was only showing 12.4 amps .

Regards. Mike

2. ### Wildman

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It would appear that on occasions you are mixing volts and amps.
So lets start from the beginning 100W panel will produce 6-8amps maximum (assuming full sun/midday/mid summer) into a discharged battery reducing as the battery gets charged.
a voltage of 10.4 will not charge a battery to do that the input voltage has to be in excess of 14V if the panel is genuinely showing 10.4Volts across the solar panel input terminals at 1.5amp then the actual battery voltage is considerably lower i.e. dead and not holding a charge.
1st step disconnect the solar panel at the regulator and measure the open circuit voltage should be around 17.5v in full sun.
Next with the panel disconnected remove the battery leave it for an hour so that any skin charge dissipates and then measure the actual battery voltage. If 10.5 or less you need a new battery between that and 12v it may recover with a full overnight charge on the mains. Fully charged and again left to stand for one hour measure the voltage again it should be in the region of 13.8V.
If the battery holds the charge and the solar panel has a decent open circuit output then the regulator which should be at least 10amp not 8amp is faulty and needs to be replaced, If the solar panel does not give a decent voltage it is faulty or parked in the shade (of a sat dish maybe?)
In the event of it being faulty the problem is generally down to corrosion in the black box on the rear of the panel and or damaged diodes. You may be able to clean it, if not or you don't feel confident then I would be prepared to buy it from to to rebuild for my workshop roof.
When removing a battery from a solar system the solar panel must always be disconnected first. The feed to the battery disconnected last.
To refit always connect the battery first and then the solar panel failure to do so will knacker the regulator.
Good luck.

Last edited: Jun 10, 2014
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3. ### cmcardle75

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I think you might be getting your amps and volts mixed up. Can you clarify which you mean when, and what sort of meter you are using to make the readings?

4. ### ScattycatFunster

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Hi folks, thanks for the above replies.
I'll be the first to admit that electrics are not my top subject.
Having said that I don't think I"ve got my amps and volts confused.
I'll try and explain things more clearly.
My Solar charge controller is a Steca solsum rated at 8.8 A.
It has a series of 4 info lights on it
The first one when illuminated shows that the unit is operating normally, it's illuminated
The second flashes red if the battery is empty, it's not illuminated
The third flashes yellow if the loads are weak, it is not illuminate
The fourth illuminates green showing the battery is good or flashes slowly showing the battery is full and charge regulation is active, the light is illuminated and steady.
I have a multi-meter but have no idea how to use it except that when the two leads are plugged in, the black into the bottom hole and the red into the next one above it, if I turn the dial to 20v I can check battery voltage.
Putting the pointy ends across the terminals of the 2 leisure batteries, individually and together, this morning I had a reading of 12.64 v in all cases.
Checking the volts on the battery terminals on the Solar controller I get the same reading. I then put the the leads across the input leads from the Solar panel and got a reading of 10.8 v.
Inside the van on the van's control panel the battery level reading shows 12.7v and the charge form the Solar panel is 0.5 amps. When the van was plugged into the mains the charge rate was 3.5 amps.

The batteries were new last summer.

The concern/problem I have is that if I leave the van off mains charge and leave the alarm on the solar charger does not keep up with the power drain and after about a week the battery level goes down to 12.4 v and the solar panel only shows a charge rate of 0.5 amps. Even in strong sunlight when wild camping in Morocco the best charge rate was 1.5 amps
I've checked the calibration setting and when the solar panel is covered and the reading is 0.00 amps. I can change the calibration settings to indicate that the charge rate is higher but then when the solar panel is covered with a solid board the panel still shows a charge is being received so I re set it to 0.00

I'm sure the Solar panel should be able to keep up with up with this minimal drainage

P.S. can my multi-meter be set to show amps?

Thanks again for any input

5. ### Wildman

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a few more points raised here.
1) an alarm is usually run off the engine battery
2) unless there is a special arrangement the engine battery does not normally get charged by solar power, that goes direct to the leisure battery, hence the engine battery will drop in voltage. When on mains there is usually a switch to choose between charging engine or leisure battery but unless a B2B is fitted not normally both at the same time.
The reading on the solar panel is confusing at 10.7V unless the diode has gone short circuit and the battery is reverse charging the solar panel no current will flow into a battery that is a higher voltage, so it may be the .5amp is a discharge rather than a charge (mind you if the alarm is fitted to the leisure battery then that could account for the .5amp discharge.
Even new batteries have been known to have a duff cell. Where is it charging from to get to 12.7V if it is just the solar then it must be charging albeit not very well however the 10.7V across the solar inputs is worrying and would suggest the panel is duff and will never charge beyond that voltage. Is the 12.7 from running the engine or mains hookup maybe.

Basically as you have no leccy experience your best bet is to take it to a caravan repair shop and have the job done properly rather than play with it and risk a fire hazard

6. ### pappajohnFunsterLife Member

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10.7v between the panel and controller in Morrocan sun ......either a damaged panel or in shade.

I suspect a damaged/faulty panel as you wont always be in shade.

7. ### cmcardle75

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It sounds like your panel (more likely) or regulator (less likely) is shot. Yes your meter does amps, but don't use it for that. It is dangerous in the amps mode.

8. ### magicsurfbusFunster

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10.7v coming directly from the panels on a sunny day is too low.

To my simple way of thinking there's something not right at the solar panel end. Can you check the voltage any closer to the panel to see if the cabling is right? Normal panel voltage on a sunny day is in excess of the maximum allowed through to the battery by the regulator, in my case 13.6v.

It might also be worth checking that your multimeter battery hasn't worn out, as that can lead to errors in the readings, but somehow I don't think that's the problem.