Customer Email Q&A | Lance Camper, 2 group 24 batteries – What size portable RV solar system?

Portable Solar Sizing Question

Here is a common email I receive about the wires and size of portable solar units. 


I’ve been thinking about moving to solar this year for my trailer, to keep the batteries charged up. Living in Nevada, I’m sure that solar panels will be an excellent solution!

I have a Lance 2295 trailer with two Group 24 batteries (we watch movies at night from time to time), and am thinking a portable solar setup would work well. As you might imagine, I have a few questions, as you guys are the experts:

1) Should I be looking at 160w or 120w set-up?

2) I was thinking I need the 160w set-up, but it’s out of stock, again.. If this is the good choice, any ideas as to when you may be getting some more units?

3) In reading about portable solar panels, there’s lots of talk about wire gauge between the solar setup and the trailer (especially when using the extension cord). What gauge wire does Zamp currently use in their wires from panel to battery?

4) finally, it sounds like it’s better to have the controller next to the batteries, rather than next to the solar panel (to minimize the post controller wire length). Your thoughts on this?
Thanks a bunch for all of your help. I hope to soon be a customer.

And my answer – shortened –

Portable Sizing

I think the 120 or 160 are both a great options. But it would depend on how much TV you watch or if you are trying to run other electronics at the same time.

Your 22′ trailer will probably use about 30-amphours a day with normal use. That’s mainly factoring the lights, fans, water pump, ect. This does’t include a fridge or other larger devices running off the battery.

The TV usage will increase this a bit more to maybe 40 to 50 total amphours a day.

The 120 can generate 30 to 45 amps in a 5 to 7 hour day. That is with really good, non-shaded, direct sunlinght. The 120-watt portable would do well for you if you only camped for a couple of days. However, you should know that you likely won’t be putting all the power you used back into the batteries. So your batteries would likely need a day or so of charging after you get home.

If you don’t want to worry about your batteries and would like to fully charge then everyday, or even run other devices – I would get the 160-watt portable.

A 160-watt portable will produce between 60 and 90 amps in 5 to 7-hours of great sunlight. This should fully cover your usage.

Portable Wire Info

The wires on the portable unit is 12 gauge wire, the length is 15′. This is the same for all Zamp portables.

The extension is 15′ and is 10 gauge wire, this helps with minimizing any voltage drop.

Special Portable Setup

Having the charge controller as close to the batteries as possible is the best setup. If you’re a good DIY person you can order an unregulated portable and get a charge controller you can mount near your batteries on your own.

Don’t mount the charge controller in a sealed box with lead-acid batteries. They can exhaust hydrogen gas and create an explosion. Rare but it can happen.

The portables and the way they are designed still kick out a great amount of power and are very efficient. Doing the modifications isn’t necessary unless you want to.

Additional Info

The Zamp Solar Portable units are designed to be connected to a battery without any equipment to install. Simply unfold it, set it up and connect it to a 12-volt battery.

The use of their extension cable will reduce the charging to the battery but it’s a very small amount. However, if you are living full time in an RV this small amount could add up.

Modifications will require a larger investment in install or time. It’s not necessary for most users but if you like to get precise, it’s fun to do. You can order an unregulated portable and do a custom install yourself.

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