Hi All. New to solar and currently working on 12V campervan. I have 3 X 220 watts panels (see specs below). A 150/70 Victron MPPT, 6awg wiring to roof. What connection method parallel (higher amps) or series (shading issues) will give me the best charging outcome. Thanks in advance
Parallel vs Series
- Thread starter Mozallas
- Start date
do you already have the Victron 150/70?
You don’t need that large of a unit for 660watts.
You could go with a mppt 100/50 or a 150/45.
With RV’s it is usually recommended to go more parallel. I would hook three panels up as 3 parallel. You will need to fuse each panel- there are MC4 fuses for that.
If you have space to add a fourth panel, then I would go 2s2p - but on a van you probably don’t.
The reason for parallel, is because in an RV we have various shading issues and it changes every time we move. Some sites will be full sun, others will have partial shade,etc. parallel does better with shade.
Good Luck
You don’t need that large of a unit for 660watts.
You could go with a mppt 100/50 or a 150/45.
With RV’s it is usually recommended to go more parallel. I would hook three panels up as 3 parallel. You will need to fuse each panel- there are MC4 fuses for that.
If you have space to add a fourth panel, then I would go 2s2p - but on a van you probably don’t.
The reason for parallel, is because in an RV we have various shading issues and it changes every time we move. Some sites will be full sun, others will have partial shade,etc. parallel does better with shade.
Good Luck
MisterSandals
Participation Medalist
3P will be 37.8A Imp which exceeds what most MC4 connectors can handle. When you consider Isc, thats a fire hazard over 40A. You'd need to remove the MC4 connectors and use something like a combiner box.
This is often an excellent solution.
With minimal shading issues, 3S works well with your SCC. I would be inclined to try this first to see if you get sufficient production.
@MisterSandals does have good points.
TheAlmightyOgreLord
New Member
Not to resurrect this thread, but I would advise using two separate SCC's for a 2s2p setup. Reason being, is the mppt SCC has no way to differentiate between the paralleled panels. All it sees is one panel no matter how you connect it. This is how they're designed.
A 4p (all-parallel) setup is expensive, requires fusing each panel, and large guage wiring. If you're going this route, an mppt is a waste because it will fall back to PWM mode most of the time running at 17V or below. And still, for maximum shade efficiency with an all-parallel setup you want 1 PWM controller for each fused panel.
For one MPPT controller I highly recomment 4s (all-series) because the wiring is cheap, fuses are optional (the high voltage current is lower than the panel's own fuses) and under low light/cloudy conditions you get well above 20V keeping within the MPPT range. It's a difference between 10 and 50 watts with 4 panels. The MPPT controller with 4s also knows better how to optimize the array for shading, because it sees it as one large panel and it's hooked up that way too. It activates the bypass diodes if one part is shaded and since it's not in parallel, the voltage stays higher and has less dips.
