Solar panel - expecting too much?

[dom_e]

Hi all

I installed a 110w flexible solar panel hooked up to an Epever Tracer BN series MPPT controller. It's connected to the leisure battery (with a fuse close to the battery), which is also connected to the split charge relay.

Over the winter, the LB gradually reduced in voltage when there was nothing drawing current. I thought this must just be because there's not much sun. Now we're in mid March and the sun's beating down on the panel (albeit with the roof down, not pointing perpendicular to the sun) I expected it to at least charge the battery a bit. It doesn't seem to be. The best voltage I'm getting from the panel terminals is around 13V. The battery is just over 12 (it's a brand new battery that I put on charge before installing). All connections seem fine. I've tried covering the panel with a blanket, disconnecting in the correct sequence, then reconnecting.

Are there any solar or electrical experts who can suggest if I'm expecting too much from a 110w panel or if there's something else that may be wrong with my setup?

Cheers

[Bob]

I would have thought a panel that size would easily maintain a battery, sounds like something amiss, but I don't know what.

I'd put a charger on the leisure battery, rather than leave it part discharged, until you sort the problem.

[g8dhe]

You have a fault! The charger when actually putting a large charge into the battery will be around 14.4 volts and once it thinks the battery is charged then it will drop to around 13.6 volts. Even on cloudy days the panel should be generating sufficient to charge, unless your in a very shaded area.
What age is your battery that it is charging ?

[dom_e]

The battery is brand new. I replaced it as the old one, which was only a couple of years old, was losing charge....possibly due to a fault with the solar set up.

If the MPPT controller is faulty, any recommendations on a better one?

[dom_e]

Another thing to note is that it was reading 13+ volts when I covered the panel with a blanket (which I did before disconnecting the terminals)!

[g8dhe]

Measuring any voltage above between 12.6 and 14.4v is common if you have only just taken it off charge. You need to let it rest for a while, 30 minutes at least for the resting voltage of 12.6v when fully charged or less if its only partially charged. Measuring a single battery voltage tells you very little about the state of charge of a battery, it needs to be measured over time to understand what is going on, which is why you rarely see me suggesting the little lighter socket voltmeters/displays as they just tend to mislead people

[dom_e]

I had a spare very low cost pmw controller for a shed solar set up. I just swapped that into the Bongo and got similar odd readings. It's a mystery. I am planning to check simple things now, starting with swapping out the cheap looking fuse for a higher quality blade fuse holder I have. I'm wondering if something like a poor connection in the circuit could be causing issues.

I'm using a proper volt meter in case that's of relevance.

Any other ideas?

[dom_e]

The mystery continues. I swapped the fuse holder to something higher quality and checked the cable connections to the leisure battery. Still no noticeable difference.

This time, I took the voltage from the solar panel with the + wide out of the cheap PMW controller and negative in the - terminal of the controller. This read around 18-19v. When I put the + wire from the panel into the controller, the voltage dropped to circa 13v. Starting the engine shows the battery voltage increase, which indicates the alternator is doing its job.

For now, I've put the leisure battery on charge.

This is getting rather irritative now!

[g8dhe]

What do the controllers say the charging current to the battery is ? Not the panel current but the battery charging current and at what battery voltage ?

[dom_e]

I'll try and figure that from the manual, here https://www.epsolarpv.com/upload/cert/f ... L-V1.2.pdf

Mine's a Tracer 1215BN

[dom_e]

Okay - I'm stumped - how do I measure/identify the charge current to the battery? Using my multimeter?

[g8dhe]

Most of the controllers will show this on there displays, either on different tabs or on the diagram on the MT50 display panel;

[dom_e]

Mine's the Tracer1215BN. There's no display on it. The low cost one does have a display and changeable settings though.

I do have a cable to connect the Epever Tracer to my laptop to see what's happening. My knowledge runs out on what some of it means though. I'll see if I can plug it in later and get something meaningful that'll help.

It's a grey day here in Wales, so I doubt much charging will be happening.

[dom_e]

Here's a live readout of the Tracer BN1215 behaviour this morning

https://photos.app.goo.gl/5BwPkmdBjAiZsGx5A

When I connected it back up (battery first, then panel), it initially gave a panel voltage of over 18v (measured using my multimeter). This dropped over a few minutes and seems to hold at around 13.3x v. The charge status says boost. Maybe it's doing its job?

It' a pretty sunny with patches of cloud kind of day.

[g8dhe]

I would have to assume that your in a very shaded area to be only getting 13.3 volts @ 0.01 Amps from the panel ?
Either that or you have a broken/shaded cell in the panel itself ?
The output from the panel even under clouded skies is normally a lot higher ! 20.7 volts from the panel and charging 0.5 Amps @ 14.7volts to the battery
Here is a the situation here;