Solar panel

[MattandNaomisRV]

Recommendations on solar panels for my RV

[4x4ord]

I’m pretty new at this solar thing but I’d recommend starting with a 40 amp MPPT charger and 400 watts of solar with two golf cart batteries. If you need more you could add two more golf cart batteries and if that isn’t enough you could add another 400 watts of solar. If you need more than that you might want to run a generator.

[2oldman]

BFL13 wrote:
There can be good reasons to have Li, but the "faster charging" claim needs to be very scenario specific.

Correct. I'm charging at 34 amps at 50v right now. Equivalent of 120. Gives my Hondas a good workout.

[BFL13]

An Li does not charge "faster" unless the Li will accept the charger's max amps, but the ordinary battery bank of the same AH size won't. Solar is generally a low amp business, with all day to recharge.

So any so-called "faster charging with Li" is not going to be realized with solar recharging. You would need a much higher amp recharge scenario to get any of that. A pair of flooded batts at 200AH at 50% can accept 60 amps no sweat. 60 amps means a lot of solar and would probably be at 60 only around lunchtime anyway.

There can be good reasons to have Li, but the "faster charging" claim needs to be very scenario specific.

[obiwancanoli]

Start with an energy audit... determine typical power needs (in watts) by looking at the back panel or bottom of your appliance, and add them up, inflate 25% for unanticipated needs, then convert to Amps (Watts = Amps X Volts; Amps = Watts / Volts.

Then, after determining how many batteries you have (or need/want), add up the total Amp Hours all batteries produce in total. If your batteries are flooded or AGM, safe to consider using NO MORE than 50% of bank before recharging (otherwise, you'll severely shorten their lifespan). If instead you have Lithium batteries, you can generally get as low as 10% SOC, perhaps more, before recharging, thus, you'll have more usable amp hours, longer lasting power, and they also recharge much faster.

Once battery type and amount are known, with a completed audit, you'll know how much power you typically need for a day. Once that is known, then consider the wattage of the solar panels you'll need. They come in a variety of sizes, just know that typically, a 160W panel might produce - at peak performance and circumstance - about 8 amps (or about 5 amps for a 100W panel). From here, you can determine how many panels you'll need, and where to mount them on the roof.

You'll likely benefit by having an MPPT Solar Controller, get one with more capacity than you think you'll need down the road (should you want to add more panels, you won't have to buy a new controller). A 30A controller will handle about 500 watts (panel) and is typical of an initial solar installation, but I've seen up to 1200+ watts of panels on some RV's, likely someone who does a lot of boondocking, where such volume comes in pretty handy.

My most recent boondocking experience has shown me that I'll need more than the 480 watt, 3-panel solar net. I have Lithium batteries, and in the low Arizona sun, with 3 fixed 160W panels flat on the roof, they produced less than peak charging capability, thus, more panels would be needed to charge the batteries faster, and to a higher level. I'm thinking another 3 panels ought to do it, and I also have one 120W portable panel I use as well, as I can point this at the sun and angle it for better charging ability.

[valhalla360]

pianotuna wrote:
Start with an energy audit in watt-hours. Divide that number by five. That will give a good guideline to how many watts of panels would work well.

YES!!!!!

Before just randomly installing as much stuff as you can fit, figure out what you are trying to do and what you really need.

No point in installing a 2000w solar array if all you need is to keep a 12v fridge going over night a few weekends per year.

[Devocamper]

We use a Renogy 200 watt suitcase. Has its own weatherproof controller and cables and is portable for times we are camped under trees the panels can be moved into the sun . Renogy also has a 100 watt set up lighter and smaller have also used that one both very well made and reliable

[CA_Traveler]

Adding to KD4ULP - Larger panels cost less in terms of cost per watt, less roof space per watt and less installation cost. For my installation in 2014 a 12V panel system with PWM was only $100 less than a 24V panel system with MPPT. So 24V panels were a no brainer for me.

[pianotuna]

Start with an energy audit in watt-hours. Divide that number by five. That will give a good guideline to how many watts of panels would work well.

[ppine]

I like Renogy panels and MTTP controllers.
About $1 per watt.

[KD4UPL]

Solar panels are not all imported from China although China does make a lot of them. My favorite brands non-Chinese brands are REC, Mission.
Solar panels are mostly a commodity and looked at on a watts per dollar basis. The best price on is typically a 60 cell panel which will be about 40" wide and 66" long. These will put out 30 - 35 volts and are what some people refer to as a "24 volt" panel. These are used by the thousands on homes and businesses and thus usually lower cost on a dollar per watt basis than smaller "12v panels". Yes, you will need an MPPT charge controller. In the residential solar business is pretty much unheard of to install any charge controller that is not MPPT. I think most of the PWM controllers are likely bought by RVers. Nothing wrong with that, it's just that PWM is far from the "standard" used in the overall industry.
Put as many and as large of panels on your RV that you can fit. Solar panels are relatively inexpensive compared to batteries, inverters, and charge controllers. Careful shopping should get you solar panels at around 50 cents a watt. If you pay more than $1 a watt it's an incredible rip off.

[BFL13]

IMO the first thing is whether there is any room on the roof for the size of panel you are looking to buy. Cardboard simulations to check for that.

Worst is the air conditioner's shadow. But spacing of all those little tank vents, radio and TV antennae, and the bigger air vents can be critical. (Although you can panel over top of some of those with higher "legs" for the panels)

[Lwiddis]

Panels are only one of the components of a solar system...panels, controller, batteries and wire. Before you buy anything do an energy use survey. What you use or what you want to use.

[Boon_Docker]

Another advantage with an MPPT controller is a higher harvest of amps from the panels vs a PWM controller.

[Gdetrailer]

time2roll wrote:
I recommend larger 24 volt home panels in series. Find some local surplus as shipping is expensive for these oversize items.
Shop by price per watt as these are just a commodity and will perform fine and out last the RV.

Those 24V panels WILL need a MPPT type of solar charge controller, more expensive than non-MPPT.

The only "advantage" to 24V panels and MPPT controller is you can use light ga wire from panels to controller..

You can also run "12V" panels in series but in reality not really much advantage..

[time2roll]

I recommend larger 24 volt home panels in series. Find some local surplus as shipping is expensive for these oversize items.
Shop by price per watt as these are just a commodity and will perform fine and out last the RV.