Solar Power forTrailer

I think an energy audit is a worthwhile exercise. I haven't really done one on my coach, but the highest draw we have is the forced air furnace. We had 300w of solar installed with a 30a PWM controller on factory "solar ready" wiring charging two 6v batteries.....barely worked. The I upped it to four 6v, added another 150w panel, moved the controller down to the pass thru closer to batteries and increased the wire from the panels to the controller to #4. Now I have all the power I need. Incidently, we don't have an inverter to run anything 120v/AC. We are all 12v and propane. Never run a genny either. Someday I will upgrade to an MPPT so I'm getting all that the solar is harvesting........but really for us it works good enough like it is to spend the $$$ somewhere else.

StirCrazy wrote:

is that a typo on the 1-1.5W/100AH, you meant 1-1.5W/1AH maybe?

anyways I don't think it is becoming less important, but rather going above that might be less important.

Yes, a typo, meant 1-1.5W per 1AH.
Having an oversize solar is good when you want it to be your only or main source of power. In rain/clouds 700W solar would work like a 70W, with daily harvest barely covering propane fridge thermostat, detectors, lights, pump, small electronics. You can still make it, battery won't go down. With 400W becoming 40W you're drawing from the battery and who knows how long the dark spell will last. My needs don't increase beyond necessary when I'm not on hook-ups. Maybe for others self-control is more difficult.

Almot wrote:

Bad news is that you will need MPPT type controller for them, more expensive than PWM type. Good news is that cable will be thinner than with 12V array. Buy used panels if you can, but they are inexpensive new either.

Many are getting Li batteries these days, the rule 1-1.5W solar per 100 AH of batteries becomes less important then.

is that a typo on the 1-1.5W/100AH, you meant 1-1.5W/1AH maybe?

anyways I don't think it is becoming less important, but rather going above that might be less important. if we got that rule and have 150 watts on a lead acid, we are usually talking about 2 6V or a big 12V so 200ish ah capacity so that would be 300 watts and I agree that's what I put on my camper when I first redid all that stuff, 220 AH with 325 watts of solar. now if we are talking LFP, you can use the full 200AH instead of sticking to the 50% rule like we do in lead acid. So, in effect we have the possibility of using a lot more capacity and depending on our existing solar to make it up. Now yes LFP will accept charge better due to the lower internal resistance less heat is generated so more of that energy goes to charging, I found about a 20% faster charge when I switched to LFP. But, when you know you can use more capacity, people have a tendency to do so. If your solar just covered you before, now you are going to be short. so, keep that in mind.

Also, I don't know why people still think MPPT is so much more than PWM cost wise. If you look at the renogy, I know you had a difficult time with yours but my 3 renogy products have been flawless. the 30 amp pwm with Bluetooth is 89 bucks, where the MPPT with Bluetooth is 190.00 yes that's more expensive but it's not crazy more, oh and that's Cdn pricing. When you get up into the 60amp and 100 amp it does get pricier but it's hard to find a good compact PWM in those ranges anymore, and for the increase in output I get from the MPPT it is well worth that extra cost. My 325watt MPPT setup puts out more charging amps in a day by about 5% over my 480watt PWM setup on my 5th wheel.

Cover the entire roof with panels. You probably won't be able to fit more than 600-800W - need to leave some space to walk around, it's easier to install when you can also walk between them. Leave 12-18" distance from air conditioner box or it would shade the panels. You'll figure out once you've climbed the roof and dragged the panels up :). Might want to cut cardboard templates (I didn't). Panels must have ~4 degree slope to shed rain water and dust, on the arched roof you'll naturally get a slope if you just attach panels parallel to the roof.

24V nominal panels are cheaper per watt than 12V nominal. Bad news is that you will need MPPT type controller for them, more expensive than PWM type. Good news is that cable will be thinner than with 12V array. Buy used panels if you can, but they are inexpensive new either.

I tried Renogy MPPT, quite an annoying device despite built-in display. Bought Victron - more money, better charging algorithm, no display - though both can be controlled via phone app. I think Victron has an optional remote display. Buy controller after you've bought the panels.

Many are getting Li batteries these days, the rule 1-1.5W solar per 100 AH of batteries becomes less important then.

Pretty much what StirCrazy said. I would go oversized on a MPPT controller because adding solar panels and batteries is fairly simple.
SJ-Chris suggested 150 watts solar for every 100 ah of batteries. I can agree with that as I have 160 watts per 100 ah.

nhall760 wrote:
I have a 2007 Artic Fox 22g trailer.I am looking to upgrade the power to use a solar power system. I am wondering what systems I could get or how I should go about installing one.

An energy audit is always a good idea, but it may or may not be needed, it's 2007 so you have a few questions depending on what you have as options. How do you want to use it? Are you planning to use the microwave when boon docking or are you only going to use 12V appliances? what batteries do you have and how many AH are they.

If you don't want to run 120v equipment then it's simple light, heat, water pump etc. That's how my camper is set up and I use about 36 AH overnight running the furnace when it's around or just below freezing so I went with a 325-watt solar panel and two GC2 batteries which were later upgraded to LFP.

My 5th wheel, however, is set up to be able to use the microwave, kurieg, and tv's a little each day so it had four 6V batteries and 480 watts of solar which I would recommend as a minimum (I have plans to upgrade the panels to at least double what I have).

for me I always go over what I need on the solar side, a bigger controller is only slightly more, and panels are the cheapest part. so, if you do your calculation and see that you need 500w of panel get 800. It will allow you to top up your batteries a little faster and give you a bit of a boost on cloudy days.

Buying premade kits is extremely expensive and if you can't do it your self find a mobile RV repair guy who will charge by the hour or a decent rate to install the equipment you buy.

You will hear a lot of people recommend Victron, if you are not on a budget ya they are good, personally I think they are way overpriced, but they work. I went with a renogy MPPT solar controler, then I sourced my own panels from a solar company. I recommend whatever brand you end up getting, for the controler to be MPPT and size the next size up so you can add more panels down the road if needed, and for your panels to be 24V split cell panels. for the actual size I took the dimensions of a couple sizes of panel and made carboard cutouts then I went on the roof and laid them out to see what I could fit up there. My theory is I would rather have one 350 watt panel than three or four 100 watt panels but sometimes you don't have the room for that.

Energy audit before doing anything.

Without it, odds are you either undersize (and are disappointed that solar doesn't work and you always have a dead battery bank) or you oversize (and are disappointed that solar is so expensive and difficult to fit).

Test it out with an inexpensive portable system and see how you like it...

Buy USED solar panels for up to 90% less than new solar panels. Just need to test them first with a voltmeter and amp-meter to make sure they are good. Then get ~30' of wire, 2 inline fuses, and in inexpensive solar charge controller. Then set it up portable-style the next time you are camping and see how you like it.

Suggestion: 150w for every 100AH of battery in your battery bank.

Here's a step by step DIY install if you are interested...
https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/30217540.cfm

I agree with the others who are suggesting an energy audit first to calculate roughly what your overall needs are.

Questions welcome.
Good luck!
Chris

Only you can determine your usage and needs. As a DIY start with a energy audit as the first step. There are many options for this including online calculators. Installation can be as simple as a few panels on the ground with wires that connect to the RV.

Some options:
Install a few hundred watts and learn.
Use someones solar as a guide and learn how that works.
There are many thousands of posts to learn from.
Hold up your credit card and have solar installed.