BlackSquirrel
New Member
This is a strange one for you all. My basic project is that I have an already existing and functional home-made UPS and I thought it would be cool to add a solar charge controller to it for some additional capability.
I'm honestly not even sure which part of my setup is the source of my problem. Maybe (hopefully) I'm just missing something obvious. Like the title says, I have a setup that works with 3 panels in series, but not 4 or 5. But in the 4 or 5 panel case I'm still below the solar voltage rating of my MPPT. Here's the system info:
My testing:
Any thoughts? I should have no problem doing 5 panels in series, it's over 30 V below the rating of the controller. And I'm well under-using the MPPT device, it's rated for thousands of watts more than I'm pushing with it.
Screenshots:
3S in 1P, 2P, and 3P in cloudy conditions:
4S1P 4S2P:
5S1P:
Victron battery settings:
I'm honestly not even sure which part of my setup is the source of my problem. Maybe (hopefully) I'm just missing something obvious. Like the title says, I have a setup that works with 3 panels in series, but not 4 or 5. But in the 4 or 5 panel case I'm still below the solar voltage rating of my MPPT. Here's the system info:
- 48 V lithium iron phosphate battery pack, home-made using individual 200 Ah cells. It is a 16S1P configuration. I have a Daly BMS that is functioning just fine. All cells were top-balanced and during the testing described below it was at about 70% charge with a maximum cell-to-cell voltage difference of about 0.03 V. This battery and BMS are known to be functional, they are currently use it as an UPS.
- The inverter charger is a SunGold unit. It is not relevant to the testing below as it was powered off and disconnected during all testing to help isolate the problem. The only important information is that I can and do charge the battery pack with it at around 15 amps, which is how I know the battery pack works and stays in balance. Per the battery specs I could charge with more amps but I choose not to.
- I have 12 identical 12 V portable solar panels. They are nominal 100 Watt panels, and have a Voc of around 22.1 V, which was confirmed on all panels with a volt meter in full sun with MC4 connectors disconnected. These are also all confirmed to be functional, I have used them before and they all generate their approximate nameplate capacity of 100 W in full sun.
- I have a Victron SmartSolar MPPT Ve.Can 150/85 charge controller. I suspect this is the source of the strange behavior.
- I have all appropriate safety protections in play, my wires are sized appropriately, OCPD on battery pack, etc.
My testing:
- 3S1P works fine. 60.96 V of solar. 300 W maximum power, actually receiving 153 W due to clouds. Screenshot below.
- 4S1P doesn't work. 91.99 V of solar. 5 W of charge power. I left it for over 30 minutes and it definitely included moments of full sun. Screenshot below.
- 4S2P doesn't work. 93.31 V of solar. 2 W of charge power. Also left for ~30 minutes to definitely include moments of full sun. Screenshot below.
- 5S1P doesn't work. 113.41 V of solar. 4 W of charge power. Also left for ~30 minutes including moments of full sun. Screenshot below.
- 3S2P works fine. 63.78 V of solar. 314 W actual power from nominal 600 W of panels (again, cloudy day). Screenshot below.
- 3S3P works fine. 65.32 V of solar. 559 W of actual power from nominal 900 W of panels. Screenshot below.
- 3S4P works fine. Forgot to screenshot this one but I measured roughly 65V solar and it charged at around 950 W of power for over 10 minutes, fluctuating with clouds.
Any thoughts? I should have no problem doing 5 panels in series, it's over 30 V below the rating of the controller. And I'm well under-using the MPPT device, it's rated for thousands of watts more than I'm pushing with it.
Screenshots:
3S in 1P, 2P, and 3P in cloudy conditions:
4S1P 4S2P:
5S1P:
Victron battery settings: