A Couple Of Solar Questions Please (1 Viewer)

[Yorick]

To explain, I've had a 150w panel on roof for a couple of years and always seemed OK. I also bought one of them folding/tilting 100w jobbies. This never seemed to add much and soon packed up. So I've in contact with the seller in the UK to sort it. I'm currently in Lanzarote.

Firstly the old set up. I have 2 x 110 AH batteries and they show 12.6v linked up.

Overnight I left the fridge and lights on, (on purpose) and this totally flattened the batteries. This morning I turned everything off and within a few hours the batteries had plenty of life in them so the old solar system is OK

The seller asked me to check the input and output values on both systems.

This system showed 20.7 on the input and also 20.7 on the output side ???. I was told it should be near 12v, but as it seems to be putting juice into the batteries, should I be worried ?
This is in the late afternoon sun at a low angle

 

[Yorick]

Second question

The folding jobby stopped having any effect after only 4 or 5 times so they sent me a new controller.
I previously tested it and it showed the same input and output voltage. And it stopped completley when hooked up to the batteries

I put the newer system in the front windscreen to get full sun impact

This 100w system only showed 10.5 input and 6.4 output.

10.5 seems a bit weedy and is 6.4v even doing anything?


Thanks

 

[BwB]

If you're talking voltage (and not Watts or Amps) then the raw voltage output from a solar panel is likely to be around 17vdc with the sun out. The regulator will take that and sort out the correct charging voltage (anything between 13.2vdc and 14.4vdc (approx.)) If you're not getting above, say, 15vdc direct from the panel (before the regulator) then the panel is probably buggered.

The van windscreen will reduce the efficiency of the solar panel, best using it outside.

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[PhilandMena]

With respect to your first question, I would agree your solar panel is indeed working. However, letting your batteries go completely flat is a big mistake and they may well be past the point of recovery. Never discharge your battery beyond 50% and ideal no more than 20%. The voltage you are measuring now is that being produced by the solar panel and once this stops charging you will see the true state of your batteries. These should be measured after being rested with non drain being placed upon them to establish their true state. I'm not sure what you mean when you say the system showed 20.7 on the input and also 20.7 on the output side . As you do not say what system you have.? The 12V reading makes sense with the sun going down indicating little power is now coming from S.P.
As for your second question, I'm no expert but attaching a second controller is probably going to cause some conflict with the original set up, which may help others to resolve if you mention what Motorhome you have.
Best of luck.

 

[Reallyretired]

are you measuring the controller output without the batteries connected? if so it would explain the odd reading and will also burn out the controller if you do it for any length of time. Always connect the controller to the batteries before connecting to the solar panel.
Possibly the same may apply to your folding panel. Connecting the battery first also tells the controller what your battery voltage is and sets it accordingly.
Output with the batteries connected and batteries fully charged should be around 13.6v but with some controllers may pulse up to 14.5v for short periods. Possibly your controller on the folding panel thinks yours is a 6v battery especially if you've run it flat which may permanently damage the batteries.

Edit - also normally best to connect all your solar panels to a single, adequately rated controller otherwise one will probably see the output from the other panel as the battery voltage and stop charging.

 

[Yorick]

I'm not sure what you mean when you say the system showed 20.7 on the input and also 20.7 on the output side . As you do not say what system you have.? The 12V reading makes sense with the sun going down indicating little power is now coming from S.P.

They asked me to check the voltage where the wires went into the controller. And at the ends of the wires coming out.

The 150w panel showed 20.7 on a flat roof. The 100w panel showed only 10.5 facing the sun, at about the same time

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[Yorick]

Another question. The old system showed same voltage at battery with and without panels attached. Should I see a difference ?

And I'm gonna detach the roof panel and just attach the folding one. How will I know if it's putting any juice into the batteries ?

 

[PhilandMena]

Another question. The old system showed same voltage at battery with and without panels attached. Should I see a difference ?

And I'm gonna detach the roof panel and just attach the folding one. How will I know if it's putting any juice into the batteries ?

I think your old panel may be working OK but there might be a problem with the controller if it is showing same reading for input and output . The controller should reduce the voltage on the output side so as not to overcharge the battery. If you want to confirm the solar panel is charging just cover it up tomorrow when the sun is strong and you should see a drop in the voltage going into the batteries. (A volt meter would do this if you have one ?).
If adding a second S.P. then they should be connected together before being wired into the same suitable controller.

 

[BwB]

Second question

The folding jobby stopped having any effect after only 4 or 5 times so they sent me a new controller.
I previously tested it and it showed the same input and output voltage. And it stopped completley when hooked up to the batteries

All the controllers I've seen specifically state they should be connected to charged batteries before connecting the solar panels (to prevent damage). Your text seems to indicate you were measuring voltages from the controller prior to connecting it to the batteries. I'm wondering if this may be the cause of your odd voltage readings? If the controller has not been damaged already, disconnect everything (I'm just talking about your folding system) then connect the controller output to a Battery (might be best doing this to a stand alone battery with no other charging systems connected, for the sake of testing) the controller should then show some form of life (either an LED lights to show its ON or the LCD display comes to life, depending on which controller you have). Then, keeping the solar panel in the dark (closed or with a cover of it) so zero volts coming from it, connect it to the controller input and then open the panel to the light. Now you can take your volt meter, as suggested in above posts, and check your voltages at the controller terminals (input and output). Your old solar sounds like it's working fine so no worries with that one. When you've sorted the folding panel feed them both through one controller (check capacity is capable of taking both pannels) as suggested by others.

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[Lenny HB]

Another question. The old system showed same voltage at battery with and without panels attached. Should I see a difference ?

And I'm gonna detach the roof panel and just attach the folding one. How will I know if it's putting any juice into the batteries ?

Measure with a multi meter connected in series on the 10 Amp setting.
Get the folding panel outside if you can, as behind the windscreen you will be blocking a high percentage of the UV and won't get a lot of output. Also with the panel disconnected you should read around 21-22 volts, like others have said sounds like the regulator is F**ked.

 

[pappajohn]

If you get the same voltage on both input and output the controller is not connected to the battery.
The controller needs to 'see' the batteries voltage to be able to regulate the output....it doesnt simply drop the input to a nominal 12v.
If it did a simple stepdown transformer would do the job.

 

[walburga]

Recently tested a (new to me, off ebay) 60 watt folding panel. Rigged it up using a new not yet fitted MPTT regulator (Techno's recommended one), and then connected to the car battery.
All the lights lit that should (on the reg)...but no amps flowing, no increase in battery voltage...checked the wiring and all appeared ok. The only thing lacking was direct sunlight. So I disconnected everything, moved the car into the sun (it wasn't raining that day) and re-connected it all. Success..approx 2.7 amps showing on the reg...so that panel is working.
I repeated this using a 100 watt panel (that will go on the van roof to join the other 100 watt panel, when the weather bucks up) and the reg was showing 4.9 amps. So that panel is working, and the MPTT reg appears to be working a treat.

Allen

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[hilldweller]

This system showed 20.7 on the input and also 20.7 on the output side ???.

Impossible if wired to a good 12V battery. 20V input is good.

You cannot run a regulator without it being connected to a battery. It must go: battery ( the regulator works out 12V or 24V needed ) then solar.

 

[pappajohn]

The only thing lacking was direct sunlight. So I disconnected everything, moved the car into the sun (it wasn't raining that day) and re-connected it all. Success..approx 2.7 amps showing on the reg.

MPPT reg should show some charge even if the sun isnt shining.
I get a couple of hundred milliamps just before it gets dark.

 

[Yorick]

Some great replies and I've learned a lot, thanks.

Now where can I get a new regulator which shows output amps ?

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[Stealaway]

Some great replies and I've learned a lot, thanks.

Now where can I get a new regulator which shows output amps ?

I've just bought this kit- works well.
You can hide the controller and all the wiring next to the battery's and have just the meter on show.

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[ludo]

Several replies to this post have stated that it is important, or even vital, to connect the regulator to the battery first and then the solar panel to the regulator, to prevent damage.

I have a new 100 watt folding/portable panel, (2 x 50 watt folded), with the regulator hard wired to the solar outputs and situated in/attached to the panel itself.

The short lead, about 40 cm long and hard wired to the regulator output has a polarity conscious plug/socket on the other end which, in turn, connects to a lead, about 4 metres long, with crocodile clips on the other end, to attach to the battery.

The instructions clearly state that the long lead must be connected to the battery first and then the short and long leads should be connected together.

Because the regulator is hard wired to the solar panel itself, this means that the regulator is connected to the solar panel first and not the battery.

Is this a problem please?

 

[Yorick]

Several replies to this post have stated that it is important, or even vital, to connect the regulator to the battery first and then the solar panel to the regulator, to prevent damage.

I have a new 100 watt folding/portable panel, (2 x 50 watt folded), with the regulator hard wired to the solar outputs and situated in/attached to the panel itself.

The short lead, about 40 cm long and hard wired to the regulator output has a polarity conscious plug/socket on the other end which, in turn, connects to a lead, about 4 metres long, with crocodile clips on the other end, to attach to the battery.

The instructions clearly state that the long lead must be connected to the battery first and then the short and long leads should be connected together.

Because the regulator is hard wired to the solar panel itself, this means that the regulator is connected to the solar panel first and not the battery.

Is this a problem please?

mine us the same. So I used to put cardboard over the panel before I connected to battery.

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[ludo]

Thanks for the reply. I expect that I could lay it flat on the grass too before connecting the 2 leads together or cover it with the bag.

 

[Yorick]

Thanks for the reply. I expect that I could lay it flat on the grass too before connecting the 2 leads together or cover it with the bag.

Yup

 

[Lenny HB]

I've just bought this kit- works well.
You can hide the controller and all the wiring next to the battery's and have just the meter on show.

Broken Link Removed

OK for the money, but not an MPPT regulator so you will not get the maximum out of your panels.

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[funflair]

I use this https://www.roadpro.co.uk/retail/12...otronic-1250-solar-computer--monitor-1705.htm

Plugged into a Votronic MPPT regulator.

Martin

 

[Stealaway]

OK for the money, but not an MPPT regulator so you will not get the maximum out of your panels.

I use this https://www.roadpro.co.uk/retail/12...otronic-1250-solar-computer--monitor-1705.htm

Plugged into a Votronic MPPT regulator.

Martin

How much!
That one item would be have increased the installation costs by 25% for quite a small increase in charging.
The complete install of these 240Watts of solar panels, charging both battery sets, came to a total of 200 and a bit quid.
I'm happy with that.

 

[funflair]

I Didn't say it was the cheapest option, "but she's worth it"

Martin

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[SomeoneElse]

How much!
That one item would be have increased the installation costs by 25% for quite a small increase in charging.
The complete install of these 240Watts of solar panels, charging both battery sets, came to a total of 200 and a bit quid.
I'm happy with that.

Yes while you have space and weight capacity available you are far better off investing in additional panels than fancy controllers.

 

[TheCaller]

Several replies to this post have stated that it is important, or even vital, to connect the regulator to the battery first and then the solar panel to the regulator, to prevent damage.

I don't know why the regulator might or might not be damaged by having the panel connected before the battery, but there is another reason that applies with many controllers.

A lot of controllers can be used on either 12 or 24v vehicle systems. They rely on being connected to the battery first so that they can sense the battery voltage & therefore know what voltage they should regulate the panel input voltage to, once it is connected.

I expect that the folding panels with the pre-connected controllers are already permanently set to 12 or 24v nominal output. I don't suppose there are many folding panels designed for 24v systems.