Maximising solar power (1 Viewer)

[Rollin]

I have 2 55W panels on my van, connected to my electroblock via a Shaudt LR02 solar regulator. Just one battery - Varta LFD90 with 90 Ah capacity.

I don't have any battery monitor currently, quite likely to splash out though as it looks like they make tracking charge level a lot easier.

In the meantime I was wondering if I could access the forum's wisdom and experience to help me get the most out of my setup!

My control panel has 2 old style analogue meters - one is current going into or out of the battery, the other is the voltage across the leisure or starter battery (there's a switch to select which battery).

One thing I've noticed is that the current reading when on solar rarely goes above 2.5A.

2.5 x 12V = 30W which is a lot less than I'd expect.

Is this likely to be because I try not to discharge the battery below about 60% - 70%?

The panels are several years old I believe.

What sort of power is reasonable to expect out of them?

Next question - what's the best direction to orientate my van to get max sun? The panels are on the front above the cab, angled slightly forwards. Should i try to park facing due south as much as possible?

Thanks for any advice!
Rich

 

[Richard n Ann]

Our van ^ The best thing by far is to angle it up towards the sun. The amperage shoots up, especially this time of year when the sun is getting lower. Your amperage readings sound about right for a flat panel but you would roughly double the output by propping it up.

 

[Lenny HB]

Not familiar with an LR02, Schaudt regulators are normally OK but you would get more output in low light levels from aa good MPPT regulator.
110W of panels in full sun in midday in mid June should give around 6.5 amps, this time of year 3-4 amps around midday.
Panel should last around 20 years with output falling by 20-25% over 20 years so your panels should be producing next maximium output.
Yes facing south will give you the best output.
As the batteries charge up the internal resistance increases so the amount of charge they take reduces, at 60 % charged they should still take the full charge of your panels.
Don't believe your meters measure the current with a multimeter inline with the output of the regulator.

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[Richard n Ann]

150w panel 1st of October pointing at the Spanish sun

 

[Rollin]

110W of panels in full sun in midday in mid June should give around 6.5 amps, this time of year 3-4 amps around midday

Is this what I could expect with MPPT? I've certainly not had anything like this just off solar! It seems to max out at 2.5A in summer and even today it was hitting that down here on the Costa del Sol. Makes me wonder if both panels are working.

at 60 % charged they should still take the full charge of your panels.

Part of the problem is I'm struggling to keep track of how much charge they do have. A Victron/NASA meter is definitely on my wish list. Say for instance I was 60% charged when the sun comes up in summer, voltage at 12.3 / 12.4. The battery starts charging before the sun is right up of course, so by the time it's midday, the battery could be at 80 or 90% charge (maybe! I have no way of telling...) and thus I assume they'd not be able to take all the panels could give.

To be honest, I've rarely let them go below 12.4V unloaded - but I've made a mistake here, I was thinking 12.4 was 60% whereas it actually seems to be 75%.

That misunderstanding does explain why I didn't seem to be getting as much juice out of them as I was expecting! That was the other part of my problem - excellent news.

I think tomorrow I'll get the multimeter out and see if I can confirm that both panels are working and wired up properly.

 

[Rollin]

View attachment 193232
Our van ^ The best thing by far is to angle it up towards the sun. The amperage shoots up, especially this time of year when the sun is getting lower.

How do you change the angle? Do you manually adjust it from inside? I would love to be able to do this on mine although I'm sure it wouldn't be a cheap thing.

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[Lenny HB]

Sounds like one of your panels could be duff.
If they are connected on the roof with MC4 connectors you should be able to unplug each one and check.

 

[WillH]

For best performance go south of Naples.

 

[Richard n Ann]

How do you change the angle? Do you manually adjust it from inside? I would love to be able to do this on mine although I'm sure it wouldn't be a cheap thing.

No, alas. I manually adjust the angle from the roof. I mounted the panel on aluminium unistrut, fitted two stainless steel hinges on the rear side and made two M10 rods up with zebs and washers to clip in the other side to prop it up. It's ok because we stay in Benidorm for 6 weeks and worth doing. It's a work in progress though, so I'd welcome any thoughts on automation

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[Richard n Ann]

 

[Rollin]

Unfortunately i can't get to the wiring in the roof at all. It's all under the panels which are riveted onto the mounting.

I did try covering each of the panels in turn with a towel, which seemed to indicate that both are working although the current was quite low at this point so I'll probably try that again when more current is being drawn.

I'll also check multimeter readings on the solar as it goes into the LR02, and finally confirm the ammeter on the panel by putting the multimeter in series as Lenny suggested.

Thanks everyone for the suggestions - even yours @WillH

 

[Rollin]

After a few hazy and cloudy days, today was perfect for testing so a quick update. Your advice not to rely on the panel meters was spot on @Lenny HB - turns out the actual current going into the battery is 4 Amps (panel reads around 2.5A). This would be more than I could hope for from one panel, and getting on the roof and covering up each panel in turn did confirm that both panels were producing about 2A each.

I got help off some neighbouring motorhomers, who had a current clamp multimeter (this sort of thing: Amazon product ASIN B01N9K61LG) which made it a lot easier. I was able to see that 4.1A was coming out of the panels, and 3.8A was going into the battery, so about 8% is being lost in the regulator / Electroblock.

The voltage at the battery is around 13.4V, so power consumption is about 50W. This is about what I would expect as the battery is pretty full, and the load is my computer, screen and inverter, which I expect to be around 45-50W.

cheers
Rich

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[Richard n Ann]

Just a note: Don't anybody buy the clamp meter in the link as it measures AC current only, a lot are like this, it must specifically state DC amps in the description if you want it for motorhome or automotive use.

 

[Rollin]

ah thanks @Richard and Ann - that explains why that one is so much cheaper than the prices they were suggesting! (€60)

 

[Richard n Ann]

ah thanks @Richard and Ann - that explains why that one is so much cheaper than the prices they were suggesting! (€60)

Here's the one I use, DC scales "DC 40A/400A"

Not expensive at all ...
And when you think it also measures AC volts, DC volts, Ohms as well as AC Amps, I'm surprised they're not more popular.

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[Rollin]

huh .. similar price, rip-off Europe strikes again?

So it measures current just by placing a wire inside the clamp (magic I tell you), but to measure voltage, do you need to connect the COM socket to the negative? And then you can see the voltage of a wire inside the clamp? If that's how it works, can you actually see voltage drop by moving the clamp along the cable?

 

[Richard n Ann]

huh .. similar price, rip-off Europe strikes again?

So it measures current just by placing a wire inside the clamp (magic I tell you), but to measure voltage, do you need to connect the COM socket to the negative? And then you can see the voltage of a wire inside the clamp? If that's how it works, can you actually see voltage drop by moving the clamp along the cable?

No, it comes with test leads and you have to use them for voltage and resistance.

 

[Northernraider]

I'm baffled with mine they seem to be putting nothing In to my battery these days and I'm not tech savvy with electrics

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