Figuring out solar

[PlayersZ28]

Looking at putting 320w on the roof with wiring & controller support for an additional 320w. I'll be using 160w panels that have a Vmp=19.08 and Imp=8.39 and wiring them in parallel.

I figure my wire run from the roof to the front gen-box area where I have my batteries to be no more than 25'. The calculators I found online vary in the results and give me anywhere from 4g to 6g for the down feed. A table I found gives me 6g.

What is the correct number (other than just going as big as I can )?

[Mustang65]

Can you fill us in on an equipment list? Panel mfr? Charge controller mfr model?

Don

[Fire_Instructor]

I've got 300w on the roof, but at 34.4v. The higher voltage at less watts actually allows me to have a smaller wire size than you, and mine calculated a 8awg. At max capacity, you will be pulling 17a approximately 25', so my chart puts that at a minimum of 8awg for up to 24' and 4awg for up to 28'....

Remember, that's a MINIMUM size... For best performance, I'd go bigger wire or higher voltage panels (if that's still an option).

Finally, while you'll get a lot of advice re solar on the various RV forums, you will find that many are opinion, based on somewhat limited experience. Mine is exactly that, but at least I try to research the info available to me!!!!

Good luck with your install!!!!

[PlayersZ28]

Originally Posted by Mustang65

Can you fill us in on an equipment list? Panel mfr? Charge controller mfr model?

Don

This is the panels I'm looking at getting. SAW Technology

Haven't picked a controller yet but I'll probably go with a lower end unit and replace it down the road if need be.

[Mustang65]

Fire Instructor is correct with going with a higher voltage solar panels will be less AMPS you have to design for.

I have a 250 watt (Residential) panel (36 volts). So, 250 watts / 36 volts = 6.9Amps between the panel and the MPPT SOLAR charge controller. The 6.9 Amps entering the MPPT charge controller will produce 20 AMPS (Max) to the battery, depending on the SOC of the batteries. I can put a total of 800 watts (60 Amps) of SOLAR into the Morningstar MPPT, so I can still add another 550 Watts of SOLAR in the future, should I need it.

As for wiring, mount your combiner box in the middle of the TT's roof, based on planning to eventually adding another 300 Watts. This way you only need to have a larger AWG rated wire from the combiner box down to the MPPT charge controller in your front storage compartment.

For your 1st two SOLAR panels, I would mount one at the front of the TT and one at the rear. This way if you encounter shade on one end, you will still be producing SOLAR power at the other end.

Don

[PlayersZ28]

I looked at the residential panels but they are too wide to fit down one side of the trailer between the vents and the edge of the roof. I'd have to put them sideways and then they would be too tight to the center of the roof due to the curve.

I'm planning to mount the combiner box near the vent stack and then bring the feed down beside that which is a straight run to the basement from where I can go forward to the gen-box.

[ddrueckh]

Look at the kits on AMSolar.com. Even if you don't want to buy from them, their kits are high end and will give you an idea of what you will need. I purchased from them because it was convenient.

[PlayersZ28]

Originally Posted by ddrueckh

Look at the kits on AMSolar.com. Even if you don't want to buy from them, their kits are high end and will give you an idea of what you will need. I purchased from them because it was convenient.

Thanks, I've looked at their products before. I'm in Canada so shipping a panel or two can get expensive. Looks like they use 10/2 wire for a single 160w panel.

[Seann45]

Hello fellow Canadian.. Personally I would go with 1ga welder cable from the panels to the charge controller.. 00 ga between the batteries and to the inverter.. Princess Auto is a good source for that.. For your panels and controller etc. make a trip across the border to get them it will pay for itself.. remember to declare the purchases to Canada Customs.

[PlayersZ28]

Originally Posted by Seann45

Hello fellow Canadian.. Personally I would go with 1ga welder cable from the panels to the charge controller.. 00 ga between the batteries and to the inverter.. Princess Auto is a good source for that.. For your panels and controller etc. make a trip across the border to get them it will pay for itself.. remember to declare the purchases to Canada Customs.

I already have 4x 6v AGM & 2kw PSW inverter I installed and used PA for the cable. A border run to get the parts isn't worth the savings as I'm about 4hrs from the nearest crossing (I'm in ON on Georgian Bay). Using 1ga for the down feed is probably overkill, I'll check PA for something in the 2ga-4ga range. If I go with a basic CC then I'll get it local, if I go with a good one then I'll get it shipped from the US as those are cheaper down south even with the exchange.