Solar wiring potential issues

[Mazrim]

Hello, I have a question on wiring panels together.

Background: My wife and I live in a converted van full time. Our knowledge in solar/electrical is getting better but still not that great. We had originally paid a van conversion company to do our electrical system and we were going to the interior, etc. That van was hit while parked and ended up being totaled. We were able to salvage our panels from that build and completed our new build under the eye of that builder (he let us work on it in his shop, etc.).
We ended up having to mix panels together due to circumstances so we are using 2 Renogy 100 watt panels and 2 Newpowa 210 watt panels. We learned that the builder didn’t actually know a lot about electrical as we kept finding mistakes, etc.

Now we are wondering if the panels are not wired correctly as we are only getting a maximum of 280 watts out of 620 in peak sun. Our jackery panels that we laid down flat to compare are producing 80 watts each.

We were assured that there wouldn’t be much loss in power by the differing panels. They did this by connecting the two renogy panels and making them into one supposedly by connecting those in a series than parallel to the Newpowa.

We ended up testing both sides separately as well to get readings of equal panels.
Newpowa in parallel were getting: 230 watts out of 420.
Renogy were getting 55 watts out of 200 with the series connection. When combined they are equaling up to the 280ish stated earlier.
They both seem low.

We also did all four in parallel and that did not change the wattage. It was the same.


Is it as simple as expecting too much? It just seems like we aren’t getting much more than when we had a 300 watt panel on our last build. We are in the upper peninsula of Michigan currently as I know location can make a difference but then why are the jackery panels performing much better?

Hoping this all makes sense and my terminology is correct. We will probably try them individually at one point soon but it’s hard to do that in our current location and would like to know if right away issues can be seen.

Thank you!

These are the panels we have:

210W 12V Monocrystalline Solar Panel

Newpowa 210W 12V Monocrystalline Solar Panel is commonly used in RV, marine, overlanding, traffic signals and various off-grid applications. Top branded, Free shipping!

www.newpowa.com

100 Watt 12 Volt Monocrystalline Solar Panel (Compact Design)

Renogy 100 watt monocrystalline solar panel, rv solar panel, off-grid solar panel for sale. Limited time sale, 10% off: Renogy10off

www.renogy.com

 

[Mazrim]

I’m also open to anything else to look into that I might be missing as there were several electrical mistakes that we’ve caught so far.

 

[MichaelK]

Can you please identify what charge controller you have? Since you are wiring in series, I'm expecting it to be a MPPT controller? There are fake MPPTs on the market, usually on Amazon or Ebay, which are just a cheapo PMW controller with a MPPT label slapped on it.

Are your panels laying flat on the van roof? Assume you won't see more than 60-65% of rated output unless panels are directly facing the sun. And that's with MPPT.

Do you have a voltmeter? Have you checked the Voc and Isc for each panel individually? The battery's state of charge will also affect the watts going into the battery. Have you watched output with a load applied?

 

[Mazrim]

Thank you.

We got ours from Renogy (40 amp) and they are flat on our roof.

Yes, I don’t expect the panels to get their full output on the roof but when talking to others that have them on their vans they are saying that they are getting max 500 and generally 300 to 400 on their 600 watts. We have never reached anywhere near that max yet (location?). And average lower then that but that average is near the Newpowa by themselves so potentially it’s something up with one of the Renogy panels as they were producing 55 watts out of 200 watts.

Our friend with a bus has 800 watts and says he gets 675 to 750 on a sunny day.

What was weird was that when we laid the portable jackery solar panels flat (trying to compare to those on our roof) they were producing the same output as when they were tilted and much higher percentage then our roof.

We do not have a voltmeter but I was looking into those the other day to check them all out when we are able to.

What do you mean have we watched output with a load applied? Assuming that you mean with things running in it, then yes. We turned everything off to get a total baseline for the panels, though.

The SOC of the battery hasn’t effected it from what we’ve noticed if it’s below 50% or above (lithium).

 

[mikefitz]

You must have a meter, need not be too expensive. I recomend you conside a meter with clamp DC current measurement,https://www.amazon.com/BSIDE-ACM91-...aWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1

You need to establish the panels are producing the correct voltages and currents ( somewhere about 60% of maximum) separately, disconnected from the controller.

The advice about connecting the two Renogy panels in series was incorrect.

Data for the panels in your links,
Renogy 100w, Vmax 20, I max 4.9, Voc 24
Newpower 210w, Vmax16.7, I max 12, Voc 19.8

By having 3 'panels' in parallel one of which was the series Renogy pair may have caused damage. Thus the need to test each separately. There is also damage may have occurred when yout van was hit.

Once you have a single panel with confirmed output ,( or borrow a panel), connect to the Renogy controller to confirm its functioning.

When testing panel output via the solar controller, load the battery significantly.

If the panel testing proves sucessful, use the two Newpower in series. The voltage difference of the renogy panels is Incompatible and best connected to a separate controller.

Mike

 

[Mazrim]

You must have a meter, need not be too expensive. I recomend you conside a meter with clamp DC current measurement,https://www.amazon.com/BSIDE-ACM91-Auto-Ranging-Temperature-Capacitance/dp/B07G84XDWH/ref=sr_1_2_sspa?crid=KOY18HHCZRB0&keywords=Dc+clamp+meter&qid=1658182458&sprefix=dc+clamp+meter,aps,180&sr=8-2-spons&smid=A1UAQ41KV8L37J&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEzNVZBQ1ZMRE1aVjVLJmVuY3J5cHRlZElkPUEwOTk2ODg2SVpPRU5PQlZUQTBYJmVuY3J5cHRlZEFkSWQ9QTA5NjEzODc1TlhYOEM0NTdDVEImd2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl&th=1

Thank you and I will get one.

 

[MichaelK]

We got ours from Renogy (40 amp) and they are flat on our roof.

If it's from Renogy, then I'd expect it to be a real MPPT.

We do not have a voltmeter but I was looking into those the other day to check them all out when we are able to.

The meter does not have to be expensive. You can get one off Ebay for 10-12$ that can read Volts, Ohms, and Amperage.

What do you mean have we watched output with a load applied? Assuming that you mean with things running in it, then yes. We turned everything off to get a total baseline for the panels, though.

As the batteries reach full charge, the controller throttles back the amperage coming into the batteries, so there is not a true indicator of output. Once you apply a load larger than the sum of your panels, the controller will accept every watt they can produce to refill the battery.

The SOC of the battery hasn’t effected it from what we’ve noticed if it’s below 50% or above (lithium).

How are you determining the state of charge?

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[Mazrim]

If it's from Renogy, then I'd expect it to be a real MPPT.

The meter does not have to be expensive. You can get one off Ebay for 10-12$ that can read Volts, Ohms, and Amperage.

As the batteries reach full charge, the controller throttles back the amperage coming into the batteries, so there is not a true indicator of output. Once you apply a load larger than the sum of your panels, the controller will accept every watt they can produce to refill the battery.

How are you determining the state of charge?

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The batteries we have, have a Bluetooth app that seems to be pretty accurate.

We have noticed what you stated when batteries are charged so thinking its pretty accurate and based on reviews on the app.


I just got a hold of Newpowa and they gave us some recommendations on how to wire them all together so hopefully that will help.

They are recommending wiring the 100 watt panel in series with a 210 watt so essentially making the four panels into 2 sets then wiring those two sets in parallel.

If we just do the 2 Newpowa than wire them in series and we should expect about 300 watts in full sun.

That should give us a good place to start until we can get a meter.
I’m suspecting the Renogy panels are the major issues based on us trying them in series on their own and only getting 55 watts.

 

[mikefitz]

Putting the Renogy 100 w and Newpower 210 w in series is a not a good idea. Where you have panels in series the current is limited to the current of the smaller panel.
The technical advice you are getting is not correct on panel wiring.
The voltages and currents of the two models of panels are quite different.

Mike

 

[Mazrim]

Putting the Renogy 100 w and Newpower 210 w in series is a not a good idea. Where you have panels in series the current is limited to the current of the smaller panel.
The technical advice you are getting is not correct on panel wiring.
The voltages and currents of the two models of panels are quite different.

Mike

Hmm…so Newpowa’s advice is also incorrect?

That’s what I thought (your explanation) but thought they must know something I don’t.

Is there any suggestions as to what would be the best way to wire these?
It’s unfortunate that the accident led us to having a mishmash of panels/original advice may have led us down the wrong path. We had the opportunity to have 400 watts of Renogy on the roof but we thought that even with loss of power from differing panels the 620 should outperform those.

 

[mikefitz]

Already suggested, the panel voltages and current differences reduce your options,

Mixing solar panels – Dos and Don’ts • SOLAR POWER SECRETS

Mixing Solar Panels: Discover Now Dos and Dont's of Mixing the Same Types or Different Types of Solar Panels. Act Now to Save Your Money!

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Connecting the two 210 watt panels in series to make one string and the two100 watt panels in a second series string , then putting the strings in parallel, may be an option. However due to the voltage difference you won't get maximum power from the array.
Having each string on a separate controler would offer maximum performance.

Before you can continue you need to establish you have no issues with the system and that each panel is working as expected, the controller is working OK, and the battery is charging correctly with no BMS protection taking place.

It's also possible errors in the instalation exist that are causing problems. Diagrams and pictures may help the discussion. Your issues may be caused by

Mike

 

[Mazrim]

Thanks for your help guys.

This may be a dumb question and somewhat touched upon in this thread. Randomly we got a 335 watt hit today with everything we have running (so over 400 in reality). Day has been rainy and cloudy and cleared up a tiny bit when it hit that number. Consistently around 300 now when before we could not get over 235ish.

This is the first time we’ve had lithium batteries before. SoC was at around 23% when it jumped in wattage.
Do lithium batteries get down really low before they bring in more watts? When the question was asked on here about SoC I thought 40% would be plenty to notice an increase if it was a battery settings “issue”. Is that normal or should I contact the manufacturer or is it possible that settings are not correct on our MPPT controller?

Currently not near any cities so have not gotten a reader yet.

 

[mikefitz]

What solar controler?
What charge voltages?
How are you measuring SOC?
It may be your batteries were at a high SOC previously.

Mike

 

[Mazrim]

What solar controler?
What charge voltages?
How are you measuring SOC?
It may be your batteries were at a high SOC previously.

Mike

We have a Renogy.
Voltages: Honestly not sure where I would find that. Sorry, again very rudimentary with our knowledge in that department.

Our MPPT controller is showing 20 amps coming from the solar panel but our battery monitor is showing 14. No sure why that is and mppt shows 100% battery while monitor shows 41%.


For SoC the batteries come with a Bluetooth app to read them.
It wasn’t until hitting near 30% that panels appeared to be doing better but now that it’s gone up again to around 40% panels are back to performing as before. Not sure if that’s normal with lithium batteries or not.

 

[Solar Guppy]

Just a guess, but sounds like your charge controller measures the voltage higher than the actual voltage at the batteries, so it correctly lowers charging. This indicates you may have wire to small for the run from the charge controller to the battery. Small wires cause voltage to drop, so the charger, the source of energy will read higher than the destination, in this case the battery.

You should make a diagram of your system, including the wire and the annotate with the specifications of each part. Not knowing about voltages is a clue that there could be many causes of your under performing system.

 

[mikefitz]

I assume its a Renogy Rover 40 amp unit.
it's necessary to select your battery type, p19 in the instructions, and possibly modify the charge perameters, p20
Any SOC reading on a Renogy controller will be inacurate. Also the calibration on Renogy products can sometimes be in error with inacurate voltage readings and charge voltage.

20 amps showm on the controller is the current Into the 12v system, the monitor showed 14 into the battery, perhaps the fridge/ lights/ inverter, was taking the other 6 amps.

Provided the battery monitor was set up and installed correctly it should give a good indication of SOC.

Usually the BMS reading of battery SOG is fairly accurate and this should be similar to the monitor value.

Lithium batteries should take maximum power from the panels until they are almost full.

Any issues with the panels, wiring, and controller settings will compromise the charging.

Simple fault finding using a meter will show up issues, for example if the voltage at the controller terminals is not the same as the voltage direct on the battery posts, there is a wiring or connection fault.

Lots of helpful folk on the forum but need lots of Imformation, what equipment, chargers, batteries, typically loads, diagrams and pictures, to provide clues.

Mike

 

[Mazrim]

Hi guys, thanks for your help. We ended up being able to figure it out/using a reader and it ended up being as simple as just connecting the two 210 watts in series. We got a little over 400 watts at one point coming in.
We expected that there would be some loss with the mismatched panels and it seems like we are basically the equivalent of a setup of about 500 or so watts now. Not too surprised by that.

Started on another issue with our dc to dc charger, now. It was running for about 10 minutes then it would cut out, cycle back up, then cut back again over and over again so essentially wouldn’t charge it.

The wire that goes from the ignition to the charger is 14 awg and the one that goes from the battery to the charger is 6 awg. It would basically cut out at 45 amps brought in. Our dc to dc is a 40 amp Renogy.

We ended up fixing the issue by using the LC port (limit current) and that dropped amps to pretty much 20 max being brought in.

Question is, is that normal or is there something I’m missing. Seems odd to drop by 50% (according to Renogy manual that’s what LC) does in order for it to function properly. And we never had that issue until recently.

If it’s supposed to and we fixed it then that’s great but seems like a lot of useable power gets dropped by using that port.

 

[Solar Guppy]

The wire that goes from the ignition to the charger is 14 awg and the one that goes from the battery to the charger is 6 awg. It would basically cut out at 45 amps brought in. Our dc to dc is a 40 amp Renogy.

Wire size is very important, 14 awg is rated for 15 amps, where 6 awg typically 50, and the longer the wire, the larger the voltage drop and heating.

So you should have a 8 awg for 40 amps from what is your alternator? ( you wrote ignition ). 14 awg is to small for 20 amps and your lucky you didn't cause a fire with that.

Here is one of many online wire charts

 

[Mazrim]

Wire size is very important, 14 awg is rated for 15 amps, where 6 awg typically 50, and the longer the wire, the larger the voltage drop and heating.

So you should have a 8 awg for 40 amps from what is your alternator? ( you wrote ignition ). 14 awg is to small for 20 amps and your lucky you didn't cause a fire with that.

Here is one of many online wire charts

I didn’t wire it. A supposed professional did. We are just trying to figure out the issues that are coming up. We were trying to avoid electrical like the plague as we didn’t want to try and tackle learning that in the time frame, etc. we had.

The 14 awg wire is coming from the ignition so that when the ignition turns on it signals the charger to start. Basically so the unit doesn’t turn on unless the ignition is on is what they told us.

The alternator is charging the car battery and the wire running from the van battery to the charger IS 6 awg. It’s the way we’ve seen it set up on several vans now so don’t think it’s that abnormal but maybe we’ve just seen the few that are out there? Aren’t they sometimes called B2B chargers (battery to battery)?

Hope that is explained better.

I’ll get some pictures tomorrow and maybe that will help.

 

[mikefitz]

The ignition cable at 14 awg and the main current carrying cables at 6 awg are about right for this instalation for cable length up to 3 meters (10 feet) , over that 4 awg would be preferred.

Could be overheating in the unit or a faulty breaker in the feed cable.

The issue may be due to exceeding the maximum current or voltage into the battery causing BMS shutdown. The unit can be programmed for charge voltage via a dip switch, see manual. The settings range from 14.0 to 14.6 volts. Try the lower setting.

Mike