Can I keep my solar array in parallel to keep volts in wires under 50V and improve partial shade performance while still using a 48V battery and AIO?

[BananaPeel]

I'm planning to have 6 x 400W panels on my RV roof. They have a nominal voltage of 42V. I also plan to have a 48V battery bank. I had wanted to avoid running any wiring much over 50V anywhere. However, all the 48V All-in-one chargers/inverters I can find call for an MPPT Voltage range starting significantly higher than 42V. The lowest I can find is 60V with many requiring at least 120V. I could wire enough panels in series to meet those requirements. However, I'd rather not because I'm concerned about getting as much power as possible in shady conditions. I'm also concerned about the safety of running that high of voltage through my RV, especially across the roof.

So, should I change to a 24V system? Are there any good 48V AIO units that are usable with a 42V solar input that I'm missing?
Or, Is there any way to connect my panels in series, but still only have cables running 42V across the roof? In other words, connect them in series in my Inverter compartment, but have all the wires from the panels stay lower voltage across the roof and down the walls until reaching that compartment. Of course, this wouldn't solve my issue of wanting all the panels in parallel for shady conditions, but it is better than nothing.
Or am I just making a big deal out of nothing and need to go with a 48V system and hook the panels up in 1-3 series circuits?

 

[sunshine_eggo]

No. 48V batteries need to be charge to mid to high 50V. PV must be at least 50% higher than 48V.

 

[littleharbor2]

Won't work. You need to wire 2s3p or 3s2p. You need at least 65 volts to charge a 48 volt bank. Are you using FLA batteries? AGM? Lithium? MPPT controller?

 

[BananaPeel]

Ugh, yes, I knew that I needed higher than the battery voltage to charge it, I just totally forgot it when I wrote the post haha.

Lithium Batteries.

 

[BananaPeel]

So I guess the real question is: Should I set up my battery as 24V and use a couple of these:

3KVA Solar Inverter 24V 110V Parallel 80A Mppt Solar Charge Controller

Hightlight: ★ALL-IN-ONE: 3KVA DC 24V to AC 120V pure sine wave inverter, 80A MPPT solar charge controller, 60A AC battery charger and automatic transfer switch. ★ LCD user- configurable: LCD display of the solar inverter hybrid offers user-configurable and easy-accessible button operation such...

sungoldpower.com

Or should I save a few bucks and stick with a 48V System? I'm wondering how much value there really is in keeping my wires low voltage and keeping my panels in parallel for shady conditions.

 

[sunshine_eggo]

Whatever your decision, factor in that each of those units will consume 50W any time they are powered on, even if you use no loads at all.

Two of them running 24h would consume 24h * 100W = 2400Wh - about the capacity of a single 24V, 100Ah battery.. just for the pleasure of having them turned on. Also, the first 500W of your solar array will exist solely to replenish that lost capacity.

These are the hidden costs of these "cheap" units.

 

[400bird]

Technically, you could run a bunch of these boost converters, one for each panel, to keep the PV voltage under 50v
But, as was already pointed out your battery voltage will above 50v most of the time.

They are likely more expensive and less efficient than running a standard series string and charge controller.

Genasun 8A 48V MPPT Boost Charge Controller for Golf Carts

You have a limited amount of space on the roof of your golf cart. These are fully waterproof, which makes them ideal for golf carts and other applications. GVB-8-Pb-48V-WP

www.altestore.com

 

[sunshine_eggo]

I doubt those can be made to work with MPPT. MPPT tries to pull too much from them, and they'll shutdown.