Solar panels for camper

[LMD423]

HI
We currently run our camper on a generator to charge batteries and etc. I have been reading about solar panels and wondering if anyone has had enough luck with this that they didn't need their generator anymore. We have a single battery 12 volt system in our camper fridge ,furnace, lights. Would 25 watt panel be enough to maintain for 2 weeks at a time in the Fall? I was thinking of putting a inverter in also to charge electronics and maybe run a TV .
Thanks

 

[FAIR CHASE]

25W is much to small. You need to look at what you will be running with the batteries and determine the total number of amps.

As a starting point, a 50W solar panel will give between around 2.7 amps.

Solar panels have really become user friendly and are now quite inexpensive.

 

[nhn2a]

Check out renogy solar panels. I don't have a camper but I do run a shed in the middle of nowhere off of 4 x 100 watt panels. I run 4 security cameras, lights, and internet.

 

[marksjeep]

A second vote for Renogy. They can be had via amazon for very reasonable prices. I've been running remote instrumentation on them for several years without a failure.

ETA - also as noted above. You need to do a power budget to determine how much panel you need.

 

[FAIR CHASE]

My experience with solar panels is Renogy as well.

 

[Lefty315]

There is a site called Wander The West, geared towards off road truck campers, van conversions, etc...
Lots of good info regarding solar on there and some fairly knowledgeable people when it comes to what you'd need to run your camper. One thing I might suggest, having had an Arctic Fox truck camper, get a second battery and install it. The furnace and lights were generally the biggest draw for me. I was going to convert to led but never did. If. You're using it for hunting season just remember the sun is a lot less efficient in the fall when it comes to charging so maybe take your generator along just in case.

 

[Gr8bawana]

A 25 watt panel is only good for about 1.4 amps which is pretty much useless, even a trickle charger for batteries is about 2 amps.

 

[Ben Lamb]

If you are planning on running a fridge on 12 V power, you really need to do the energy budget.

If your RV fridge runs on propane, go with that and you'll cut your power consumption tremendously while only sipping propane.

 

[nhn2a]

I'll add it can be a pain to calculate out your energy needs and figure out the proper size battery bank. As others have mentioned, the fall you get a lot less performance out of the panels as well as daylight available. Also most battery manufactures don't recommend draining the batteries below 50% so factor that into your calculations. Then there is the possibility of rain or just clouds for days at a time which you'll need to factor into your storage reserves. It took me about a year of trial and error before I could have a system that would run constantly without dying every couple of weeks. I failed to account for all of the above mistakes but thankfully for me it was just a matter of adding an additional battery to the array and adding a couple more panels which all in all was still rather inexpensive.

 

[Wes Mantooth]

Check out this page from Expedition Portal. Great site.

 

[FAIR CHASE]

I'll add it can be a pain to calculate out your energy needs and figure out the proper size battery bank. As others have mentioned, the fall you get a lot less performance out of the panels as well as daylight available. Also most battery manufactures don't recommend draining the batteries below 50% so factor that into your calculations. Then there is the possibility of rain or just clouds for days at a time which you'll need to factor into your storage reserves. It took me about a year of trial and error before I could have a system that would run constantly without dying every couple of weeks. I failed to account for all of the above mistakes but thankfully for me it was just a matter of adding an additional battery to the array and adding a couple more panels which all in all was still rather inexpensive.

If you can do basic math, it is not a "pain" to calculate energy requirements.

There is a reason deep cycle batteries are used in a properly setup mobile solar system.

 

[LMD423]

Thanks for the info and advice. I will figure out energy draws and more than likely use propane on fridge.

 

[nhn2a]

If you can do basic math, it is not a "pain" to calculate energy requirements.

There is a reason deep cycle batteries are used in a properly setup mobile solar system.

Sorry FAIR CHASE but I disagree that its simple math. There are a lot of variables that go into the system beyond just energy usage and battery capacity. i.e weather, time of year, sunlight available, controller efficiency, etc. If you are looking for a cheap solar trickle charger than yes its easy to put it out and forget about it until something is charged but if you're looking to run anything long term off of a solar system and expect it to be self contained then there is a lot of factoring and math that has to go into it.

 

[FAIR CHASE]

I completely agree if after adding up all components amp usage you do not up the total usage by 50% to compensation for what you stated.

 

[Brad NSW]

We put one 240 watt on our trailer. If sunny, it will recharge by mid afternoon. We're stingy with lights, may watch an hour of TVv.

I've got another 240 watt panel in the garage and will probably put it on this summer....depending in how my wife does with one, for two weeks while I elk hunt. We'll see how many times she has to fire up the Honda ggenerator.

 

[Epfd217]

I know I wrote a lot. If you read nothing else, the best investment you can make today towards this goal is to upgrade your battery bank. You will need to do it for a solar setup anyway and if you choose not to go the solar route, more and bigger batteries will mean fewer runs of the genny.

When Fair Chase says its simple math, he is somewhat correct. Add up your power usage. A good place to start with this is called the Kill-A-Watt

Measure your usage over 1 day, 3 days and 1 week or two if thats what you're going for. Once you've done your energy audit and you know what you need for power then you plan the power storage. A typical RV using a 12v fridge, lights, radio etc will use 25-40amps a day. Add in a furnace and you can double that amount, especially depending on the size of the camper.

Batteries: A typical 12v group 24 battery provided by the dealer is good for 75 amp hours, but to make the battery last you shouldn't discharge lower than 50%, so now you're only got 37amps of storage or about one days worth of power. Add a second battery and you double the days. A grp 27 12v battery or a grp 31 battery will give more power and more hours if you've got the room on the tongue. 2 - 6v batteries wired in series will give more power in the same footprint as two 12v will. Two 12v grp 27 batteries will get you 170 amps while two 6v in the same size will give you over 210 amps. Thats almost an extra day of power in the same footprint.

The fuzzy math described by nhn2a is that no part of electricity is 100% efficient, so everything has to be designed with the least amount of loss and oversized to account for short days and occasional bad weather. Additionally solar is designed based on power use AND battery bank size. they should be matched so as not to waste time, money or power. There are numerous websites and calculators out there.

I highly recommend HandyBob's blog. Just guessing on your setup, two Trojan T105 batteries coupled with 200-400 watts of solar and a PMW controller will suit you well.

Also, not sure what kind of electronics you're charging, but if they come with a car charger, they already charge off of 12v so using an inverter to charge them would be an enormous waste of power. Add some 12v sockets in your camper that are tied into the 12v system.

As far as running a TV, I can run our 32" flat screen and the blueray player on a 400 watt inverter without issue. Not much else requires AC power in our rig. Things like toasters, coffee makers etc are huge power hogs and require considerations when using.

TONS and I mean TONS of info on this topic out there. Just be careful of too many suggestions. Many people are willing to spend your money for you.

 

[grizzly_]

I got the Renogy 200W 20A Rover MPPT system from Amazon and love it. I run two 6V batteries and haven't needed a generator since I installed the panels. It fully charges the system by early afternoon, even on overcast days.

 

[Jim/Wa]

I run a similar system on my truck camper as grizzly: 2 x 100W panels, 40A MPPT charger, and 2 6V golf cart batteries. I also replaced all my lighting with LED lights and replaced my fan with a Maxair fan that has 10 speed settings with the lowest ones drawing 0.2/0.4 amps. I can run indefinitely as long as the propane doesn't run out. Other than the TV, once you've replaced your lights with LED's your next biggest electricity draw in the fall will most likely be the furnace fan (assuming your fridge is propane). Not much you can do about that if you want heat. I also charge all my electronics including my computer and 18V cordless drill using 12V. Mostly likely you can avoid the inverter for all but the TV.

 

[grizzly_]

I also charge all my electronics including my computer and 18V cordless drill using 12V.

I don't have an inverter on my trailer so have to charge phones, GPS, etc with a separate portable solar panel with a usb port.

Is there a good way to use the Renogy systems we already have? Like a 12V converter plugged into the "Load" port?

 

[Epfd217]

I don't have an inverter on my trailer so have to charge phones, GPS, etc with a separate portable solar panel with a usb port.

Is there a good way to use the Renogy systems we already have? Like a 12V converter plugged into the "Load" port?

Grizzly, phones GPS etc already charge using 12v. You do not need an inverter and using an inverter would be a huge wastre of power because you are converting 12vDC to 120V ACthen back to 12vDC for your charger.

You have two easy options. Both involve adding an outlet to the 12v system. Find a light or light switch in your camper that runs when the camper is on battery. Remove the cover or the switch etc. Make sure you know which is pos and neg, then add it another outlet for 12v (cigarette lighter) or the new super easy way is to add a new switch plate that has USB outlets. You connect the USB outlets to the 12v system and you can charge your devices using the same USB cord you would use for the mini solar panel. Also great for charging portable battery banks.