I'm building out a cargo trailer conversion for myself. I was just gifted these 4 - 100 watt panels. I have 4 -230 amp hr GC 6v batteries that are 3 months old, but never installed, a Victron 110/30 Smart Solar charge controller and a 2000 watt 12v pure sine inverter. I know the Victron is rated for 400 watts max, so what would be the best way to wire the panels to get the most out of them using this controller? Since I already have the inverter, I'd like to keep the system 12v.
Best Way To Wire These Panels
- Thread starter jwh92020
- Start date
MisterSandals
Participation Medalist
Not true. Are you thinking that 30A charging and 12.8V battery = 384W and thus rated for 400W max?
If you build your battery bank as 25.6V (aka 24V), and put all 4 of you 6V batteries in series, your 100/30 can use 30A x 25.6V = 768W.
But if you are sticking with the 4 small panels, then it does not matter.
You need to keep the input volts below 100V. Turns out the sweet spot (from many other threads) is to arrange the panels in 2S2P configuration. Folks have had great success with this.
Thanks for the explanation. I need to keep the system at 12v since I already have a 12v inverter. I'll look at the 2S2P set up for the panels.
MisterSandals
Participation Medalist
I explained 2S2P in this post but most of the thread talks about 4x 100W panels.
Noob question: parallel and series set up for 4 panels
I suspect its called a Victron 100 and NOT a Victron 105 for a reason.
diysolarforum.com
MisterSandals
Participation Medalist
It creates a voltage that 1) will not destroy your SCC in cold temps, 2) is in the optimal range for the Victron MPPT algorithm, 3) has an elevated voltage over 4 in parallel so that it starts charging earlier (when voltage ~5V over battery charge voltage) and charges later in the day (maintains higher voltage longer than a single panel).
You will need something like a Y pair of cables (+ and -) to combine the 2 strings in parallel. Its $15 on Amazon - search with your connector type (MC4 ?) and "Y Connector".
Bud Martin
Solar Wizard
- Joined
- Aug 27, 2020
- Messages
- 4,844
4 in parallel the current will be twice as much of 2s2p so more Voltage drops on the wires using the same wire gauge.
The Vmp is about 17.5 so if you have low light then Victron MPPT may not operate at its best to charge your battery, most SCC wants the PV input to be about 5V above the battery Voltage.
You can do experiment to find out what the best setup for your system will be.
The Vmp is about 17.5 so if you have low light then Victron MPPT may not operate at its best to charge your battery, most SCC wants the PV input to be about 5V above the battery Voltage.
You can do experiment to find out what the best setup for your system will be.
Now I get it. Thank you.
Cool. Thanks for the info. I'm going to go with the 2S2P configuration.
We have three 100 watt Renogy panels and one 170 watt GoPower panels wired in parallel to a Victron 100/30 SCC on our camper for a total of 465 watts. It works just fine. Because of the mismatched panel we would lose 65 watts when wired in series, but only 5 watts wired in parallel.
The best we've seen so far is 350 watts and 21 amps. Perhaps we'll see 400 some day. If we wire in series the best we'll probably see is 350 watts. Only at the equator will we see 465 watts. There's theoretical and then there's actual practice.
We also have a Victron BMV-712 battery monitor that communicates with the 100/30. For jollies I wired the three 100 watt panels in series and while it did provide charging for perhaps an hour earlier in the morning (batteries were full by 11 am) the amps provided were minimal at best.
OTOH, if I had four identical panels, like you have, I'd wire two pairs in series to help combat shading, like I just you have decided. Perhaps I should have stated this first or not even posted.
Enjoy,
Perry
The best we've seen so far is 350 watts and 21 amps. Perhaps we'll see 400 some day. If we wire in series the best we'll probably see is 350 watts. Only at the equator will we see 465 watts. There's theoretical and then there's actual practice.
We also have a Victron BMV-712 battery monitor that communicates with the 100/30. For jollies I wired the three 100 watt panels in series and while it did provide charging for perhaps an hour earlier in the morning (batteries were full by 11 am) the amps provided were minimal at best.
OTOH, if I had four identical panels, like you have, I'd wire two pairs in series to help combat shading, like I just you have decided. Perhaps I should have stated this first or not even posted.
Enjoy,
Perry
MisterSandals
Participation Medalist
I think the OP is done with this thread so i will indulge...
What are the Voc and Isc specs of your 4 panels. Maybe there is something creative that can be better than 4P?
Similar threads
