Gifted PV panels, how to use them?

[Randolph]

I've been given two left over Solarword 345, 24vt nominal, 72 cell panels. I want to use them for an RV set up that will have a shore power inlet, a transfer switch, inverter and a Progressive Dynamics charger.
Panel specs:
Voc. 47.8 vts
Vmpp 38.2 vts
Isc 9.75 amps
Impp 9.10 amps
efficiency 17.29%
my question is what configuration would make the most sense for my application. I'm not going to depend on solar very often. I can plug in to shore power most anytime. I have 12 volt lights from the vehicle battery, but was hoping to power a few 110 volt items such as a tv, computer, teapot, fan.

So was thinking 1. Panels in parallel with Morningstar 45 PMW controller, 1500 watt inverter. I only have room for 4 batteries, thinking 6vt b(220ah or 300ah)
OR
2. Panels in series with Morningstar 45 MPPT controller, 1500 watt inverter and the same battery bank.
OR
3. Another way?

[NEOH]

I have 12 volt lights from the vehicle battery, but was hoping to power a few 110 volt items such as a tv, computer, teapot, fan.

Do not use your vehicle battery for deep discharge

Use an MPPT Controller with those PV Panels, otherwise you will lose way too many Watts.

[SunEagle]

Option 2 with the MPPT CC is a better plan.

Although with a 12volt system your total panel wattage can generate close to 60 amps (2 x 345w / 12v = 57.5a) so your charger should rated 60amps.

Your battery system should be rated between 450Ah to 650Ah which translates to having a C/8 to C/12 charge rate.

[Randolph]

Thanks to both of you.


Ok, I'll go with the MPPT Morningstar CC and my (2) 345 watt 72 cell panels .

Sun Eagle, the battery system you mentioned (450 to 650Ah) is that @12 0r 24 volts? If 24 volts, would my idea of using 4 305Ah 6 volt batteries in series work out?


The solar co. my friend hired to dismantle the solar system she decided she didn't want told me that the two panels I was getting could be used with a PMW CC because they were 72 cell nominal 24 volt panels. Is that just a case of less expense but less efficiency?

[sensij]

.

Sun Eagle, the battery system you mentioned (450 to 650Ah) is that @12 0r 24 volts? If 24 volts, would my idea of using 4 305Ah 6 volt batteries in series work out?


The solar co. my friend hired to dismantle the solar system she decided she didn't want told me that the two panels I was getting could be used with a PMW CC because they were 72 cell nominal 24 volt panels. Is that just a case of less expense but less efficiency?

right. With a PWM, your panel output would typically be between imp and Isc, slightly above battery voltage. In summer heat, when Vmp is close to battery voltage, there isn't as much difference between pwm and mppt. In winter, when Vmp is closer to the STC value, the loss is worse. (28 V x 9.5 A with PWM vs 38 V x 9.1 A with mppt).

With a 24 V system, you'd be fine with a 25 A or 30 A CC. 305 Ah battery at 24 V is at the upper limit of what those panels can support, assuming mppt and that you've got them mounted at an optimal orientation.

[SunEagle]

Thanks to both of you.


Ok, I'll go with the MPPT Morningstar CC and my (2) 345 watt 72 cell panels .

Sun Eagle, the battery system you mentioned (450 to 650Ah) is that @12 0r 24 volts? If 24 volts, would my idea of using 4 305Ah 6 volt batteries in series work out?


The solar co. my friend hired to dismantle the solar system she decided she didn't want told me that the two panels I was getting could be used with a PMW CC because they were 72 cell nominal 24 volt panels. Is that just a case of less expense but less efficiency?

I based my calculations on a 12v system.

If you are going with a 24v then that 45A CC is plenty big and you will only need a 300Ah battery system. So 4 of those 305Ah 6V wired in series will do the trick.

[Randolph]

Terrific! Really helpful info. Thanks !!!