I have 8 400 watt panels and two sets of 2s2p into two MPPT’s. They work fine with my old LiTime charger and MrPwr mppts.
I hooked the panels into the Victron and I’m only getting 5 -8 watts when I get about 60-80 watts with the other MPPT. I have it set for 48V battery and also have the battery type set for Lip04 battery. I have one 48v battery connected in parallel to another bank of 12v batteries in series for 48v.
Batteries SOC are 84% and at 53.04 volts
I also switched to run a string of 3 panels in series to raise the voltage to see if that made a difference.
Voltage is well above batter voltage but there is no current coming in. Again, when I hook them up to the other mppt chargers I get the normal amount of power.
No VE. Direct or CerboGX component. Just bluetooth for monitoring the input/output along with smartshunt. Both are charging now but with about half the wattage generation I was getting from the other MPPT controllers. It is possible those MPPT’s were not displaying correct wattage as the data did not add up to what the smart shunt was seeing when I added the combined wattage I was getting from the two other charge controllers when I last tested this morning (getting sick of plugging the old ones in to compare lol).
This is what I’m getting currently with 4x 400 watt panels per charge controller. It is a very socked in day but I feel like I’ve seen around 150watts vs this 90 watts with the other charge controllers. It’s hard to compare quickly but when it’s socked in like this the amount of light doesn’t change much.
Went back to rotary switch selection and things picked up again a bit. I’m closer to that 150 watt range. Think I’ll just let this ride for a few days and see what happens when I get a little sun.
Have you commissioned your panels? This is an important step to rule out any bad cables/connections/panels/etc, and give you a baseline performance that you can compare to in the future.
For clarity, there are a lot of commissioning steps, but the critical commissioning tests are;
physical inspection - we can prob skip that if these other tests come out fine.
electrical test; Voc and Isc, comparing to the theoretical and the past tests.
and the required tools are at minimum; voltmeter & current clamp or shunt.
Voc is easy - just turn off your isolator, check the voltage at the isolator, and document the result.
Isc is harder - you need to short out the array and check the current with a current clamp or shunt. You can’t do this by looking at the mppt data on a solar controller because this is not Isc, its a constantly moving number somewhere around Imp. Be careful when opening a contact on a shorted array - you can start an arc.
If you don’t have your expected array Voc/Isc/Vmp/Imp numbers and expected production, post your panel specs and location (city is close enough) and i’ll build you a table.
@Nakean ; in your case, that 1 to 5 watt production looks like just the power to run the MPPT, so i would expect its just a setting in the MPPT that is preventing the MPPT from being allowed to shovel power down to the battery. The fact that the MPPT was in BULK mode means that its NOT a problem of an open circuit or blown breaker - these faults would result in the MPPT going to FLOAT immediately.
I plugged each panel into the mppt that was working and each got 18watts on their own so I figured each panel was working as it should. Messed around with the battery profile selections a few times and for some reason that seemed to help. I have the rotary selector where it should be and have that as my selection. Not sure if there was a conflict there before.
Anyhow, I think it’s working as it should but thought I received a little less power than i ought to. Chalking it up to a really foggy day, since it was. Perhaps it was truly thicker than it usually is.
Having all the components be Victron and accessing all the information in one app is so amazing! Wish I could get daily generation of both MPPT’s added together on the application but oh well.
That’s more of a VRM and GX feature - you should try it out.
A Cerbo S-GX would probably be enough for you, it lacks some of the ports of a Cerbo GX but otherwise is identical. If you don’t mind rolling up your sleeves, get a Raspberry Pi, load a free copy of VenusOS on it, and you have almost the same thing (same software, just no dedicated VE.Direct ports or VE.Can ports).
I use a lot of Venus-on-Pi , with the Victron USB to VE.Direct cables to connect the MPPT controllers, and if necessary a MK3 cable to connect any MultiPlus devices.
Then, you get everything that the VRM has to offer, and its a lot.
The only downside to the GX devices is their cost - a Cerbo GX in NZ costs more than a top grade panel, so a lot of customers don’t see the value compared to just looking at VictronConnect on their phone and putting that $ into adding 1 more panel.
Message back if you want to go down the GX or Pi route, I can point you in the right direction.
18w per panel seems still way too low.
To work out if the problem is on the panel side or the battery side, you really have to put one panel on the cables that go out to the array, take the leads out of the MPPT, and short them out. This is the only real test that you don’t have a bad connector somewhere.
Were your MC4 connectors crimped with the correct tool?
See this post about badly crimped connectors; This is why you use the correct tools
Once you have a Voc test (open circuit voltage) and an Isc (short circuit current) test done, you can move on to the battery and settings side
I was literally looking to see if anyone on ebay sold raspberi pi with Venus OS loaded already. I once bought a smart outlet that was already loaded with a different firmware I needed to tie into my NAS and smarthome application (Tasmoto I think). I know enough to know I don’t know much and have just stood on the shoulders of smarter people than me that know how to make this stuff so simple.
I’m not sure about all the cables. I know after I got started I definitely invested in the correct wire crinper and used the plastic tools to make sure they were screwed on all the way. There is a lot of thread still showing on the mc4 that came on the panels though.
I would like to accurately test each panel first and start there. I have a voltmeter, should I get an amp clamp meter? Can you only do this testing in full sun?
Its best in full sun, because that way you don’t have to deal with the suspicion that a lower value might have been from a slightly heavier cloud than the panel 5 minutes ago.
Having said that, you should be getting a heap more than 18w - i get 18w from a 410w panel inside our factory where the only sunlight is filtered through a couple of opaque roof panels.
You can do a fake current clamp by putting your MPPT controller on a known good battery that is ~50% charged, its a lot cheaper than a ~$300NZD fluke clamp, it just won’t be quite as fast or accurate.
To do this, basically do what you already have done - connect one panel at a time, in full sun, to the MPPT, with a half charged battery connected. A Lead acid is easier, that way you know that a BMS isn’t getting in the way of the charge current.
On a 400w panel, you should be getting around 3xx watts in full sun, depending on where you are. Let us know what country and we can guess at your expected percentage of STC (Standard Test Conditions), which then translates to what you should expect in terms of watts or amps.
Also, your panels look like 40v panels, so ~10A Isc and ~8A Imp (current at max power point), but give us your panel specs (Voc, Isc)
If you can get a Pi (Pi4 is best), i can send you an SD with the latest VenusOS pre-loaded
