Critique my solar charger/battery monitor setup?

[Buddha.]

I then let the truck have a rest and gave the Progressive Dynamics converter a test. It's the 60 amp model with "charge wizard" (smart multi stage charger).
Notice the difference between the voltages at the charger and at the battery 25' away. From the factory the charge wire from the converter is 6awg. There is no dedicated negative lead between the converter and batteries, it uses the frame as it's negative lead.

 

[john61ct]

A great example of how not to set it up.

I hope the bank its feeding is not an expensive one, it will need replacing much faster than if done properly

 

[Buddha.]

I finally got the solar panels and their associated wiring installed on Sunday. 4 100w Renogy panels series/ parallel. I’m surprised to see the twelve volt panels in series putting out 37 volts, I thought it’d be closer to 28-29ish.
I’m a little underwhelmed by the wattage being produced but three of the four panels are slanted slightly north.

Can anyone tell me why the solar controller is reporting 3.2 amps going to the battery while the battery monitor is reporting 7.3 amps going to the battery? This is with the trailer disconnected from shore power and my truck.

Am I missing anything? How does it look?

 

[Buddha.]

Alright, still figuring out what I don’t know I don’t know.
When the solar would only make 120w it was because the batteries were already full(and equalizing).
When I turn everything on I can to draw down the batteries the solar output goes up, because of course it does.
This is with every 12v load turned on. Three roof fans, furnace blower, all the LED lights, my 12v TV and stereo. The battery was completely full just prior to this.

 

[Buddha.]

That’s half of the solar panels’ rated output and according to my battery monitor it wasn’t quite keeping up with the load. It’s a bright sunny morning and three of the four panels are on the north side of the trailer, so they’re slightly angled north due to the roof's slight crown.

 

[rayra]

too many unknowns to really comment on it. Panels flat mounted? You mention 'slightly north', which I take to mean on the lateral crown of the roof on the offside from the sun. Not really close to the optimum angle for a panel, and that combined with the fullness of the storage battery are both going to drive down output / potential.
The the issue of time of day, height of the sun, your latitude etc. and you can readily drive down the potential of a panel.
The only way to really gauge the max panel output is place them fully perpendicular to the sun on a clear day, full sunlight on the panel and basically a dead short situation on the panel wiring, current running thru your meter. No battery , no controller. Then you have a better idea what the max output of your panels are. Then any other reduction of that output is due to your configuration or controller / battery.
even cleanliness of the panels can be a huge issue, especially with a flat-mounted panel and sun angle.

Why are they in series? Where you deliberately going for a higher combined voltage? Is it a requirement for some other component in your system? Or maybe a wiring convenience thing? I ask as series wiring introduces other potential (no pun intended) problems. A bad panel, a bad cell, a bad or corroded wiring connection and you can lose much of the power upstream from that fault. With a parallel wiring layout you avoid that. LIkewise if your panels are a type where a small bit of shade on the panel can utterly disrupt its output, the panels upstream could be in full sun but likewise thwarted by a downstream panel having a patch of shade on it. And then most of your array is rendered useless.

Also don't know why the battery monitor would be reporting twice the Amp as the charge controller. Either one of the devices could be off, or even both. They ought to be different in that they are reporting different things. I'm not sure how they'd interact, both hooked up to the same connections, when the charge controller is trying to do its thing. I mean if the charge controller is doing its thing that ought to be interfering wth the battery monitor's accuracy, if they are both connected to the same terminals.

 

[luthj]

A panels rated output is actually under standard test conditions. The panel is not hot, the light is direct on, and there are no wiring or controller losses, and there is not dust/dirt on the panel. Typically 80% of rated when hot is a good output. Incidence angle matters a lot. Best option is to test when the sun is perpendicular to the panel.

 

[luthj]

I typically see about 75% of rated at noon on a hot day. My panels are flat mounted, so they don't get much convective cooling. The panels will make 75% for a couple hours, then taper on each side of that. Panels do loose capacity over time. A few percent over the first 2 years, then maybe 0.5-0.8% per year there after.

 

[Buddha.]

Why are they in series?

Mostly to get less losses with the standard 10 gauge solar power wiring. Also it's probably less total wires I have to run.
I was hoping to minimize shading on the panels. I mounted them in such a way that they wouldn't get any shading from the trailer itself, TV antenna, roof vents, AC unit.

 

[Buddha.]

A panels rated output is actually under standard test conditions. The panel is not hot, the light is direct on, and there are no wiring or controller losses, and there is not dust/dirt on the panel. Typically 80% of rated when hot is a good output. Incidence angle matters a lot. Best option is to test when the sun is perpendicular to the panel.

I think I'll flip the trailer around so the panels have more direct light and see what happens.

 

[Rando]

I finally got the solar panels and their associated wiring installed on Sunday. 4 100w Renogy panels series/ parallel. I’m surprised to see the twelve volt panels in series putting out 37 volts, I thought it’d be closer to 28-29ish.
I’m a little underwhelmed by the wattage being produced but three of the four panels are slanted slightly north.

Can anyone tell me why the solar controller is reporting 3.2 amps going to the battery while the battery monitor is reporting 7.3 amps going to the battery? This is with the trailer disconnected from shore power and my truck.

Am I missing anything? How does it look?

View attachment 582341View attachment 582342

The solar controller is showing the current FROM the panels - 3.2A at 37V = 120W. The MPPT converts this to 7.3A at 15.6V = 114W into the battery. The measurements are entirely consistent. If you scroll down on the solar controller screen it will show you the amps into your battery as well.

 

[Buddha.]

The solar controller is showing the current FROM the panels - 3.2A at 37V = 120W. The MPPT converts this to 7.3A at 15.6V = 114W into the battery. The measurements are entirely consistent. If you scroll down on the solar controller screen it will show you the amps into your battery as well.

Thanks, I knew there was probably a simple explanation.

 

[john61ct]

The only metric matters, is Ah into the battery bank per 24hrs, and whether that is enough to

get the bank to 100% Full (if lead), or

with LFP you just want a bit say 10% more than what you use each day, again Ah per 24hrs.

Obviously voltage matching the bank specs.

Don't bother even looking at volts / amps into the SC from the panels.

Note "12V" nominal panels are usually at least 20-22Voc rated.

To be able to avoid serialing, better to use 40Voc panels for greater efficiency gains from the Victron MPPT.

Choosing voltage / serial vs parallel etc based on something as trivial as wire gauge, is tail wagging the dog.

Getting a tiltable rack so panels are at the correct angle can double overall production.

 

[rayra]

Mostly to get less losses with the standard 10 gauge solar power wiring. Also it's probably less total wires I have to run.
I was hoping to minimize shading on the panels. I mounted them in such a way that they wouldn't get any shading from the trailer itself, TV antenna, roof vents, AC unit.

Understood but I'd still recommend separate parallel wiring to the charge controller. Or even to a central bus-bar / junction to keep the cost down on parallel wiring. THen a heavier wire to the controller for the combined amps.
That way if you have a panel failure or spot of shade you don't truncate / kill your power production.

 

[Rando]

Most/all modern solar panels have bypass diodes, so if you have shading or a cell go bad just that string or panel drop out, not the whole series of panels. The whole series/parallel discussion is a complicated one, there is no general rule that one is better than the other so I would go with which ever is less work/$.