RV Solar panel

[bayfly]

I am in the process of replacing my current snowmobile hauler/camper and am interested in hearing opinions on the use of solar power in the camper. One of the trailer options includes a 100 watt solar system, a 2000 watt inverter, a two 12-volt deep cycle batteries. I realize solar may not be much use for winter camping, but I think it would be helpful for spring/fall ATV trips where shore power may not be available. I will have a generator as well but would like to be able to limit its use as much as possible. I envision powering the LED lights, device chargers, refrigerator, and furnace fan with solar power. I am a novice on this topic and would like any opinions on if others have found these solar panels useful, if the battery capacity should be expanded, etc. Thanks in advance for any information.

 

[heckler56]

When I bought my rv a few years ago I was totally inept about solar and batteries. I still am today but have spent big $’s and allot of personal time upgrading the rig.

It’s a journey but try and follow this: #1) add up what you will be running. Everything has a wattage and amperage per device. My rv frig consumes 4 amps, times 24 hours, would consume if running all day and night 96 amp hours. Odds it won’t run the whole time but this gives you and idea. Your inverter will consume amp hours and so on. #2) Agm or flooded acid batteries are sold with a label to tell you how many amp hours available, but here is the rub, those two styles of batteries breakdown after 50% of that is consumed. So you really only get useable 50% of the amp hours listed. #3) Solar. If you want to regenerate your batteries by solar rule of thumb is the total of wattage from your panels should be 2X the batteries’ combined (safely) usable wattage. In my case I have 200 amp hours usable and should have 400 watts in solar panels. I only have 300 watts so if there are multiple days in a row no sun my batteries will fall behind.

Next lesson will be: solar controller. Should you go with a mppt or pwm…

 

[bayfly]

Thanks Heckler. The more I read on this, the more I am leaning to investing in good lithium batteries for now and monitor my usage to determine what I will need if I choose to do solar later. Would that be a mistake in your opinion?

 

[heckler56]

Thanks Heckler. The more I read on this, the more I am leaning to investing in good lithium batteries for now and monitor my usage to determine what I will need if I choose to do solar later. Would that be a mistake in your opinion?

Lithium is what I switched my RV over too. Since you will be in colder environments you will want one(s) that have a built in heater. Lithium, in general, will get damaged if charged below 32 degrees. Having an built in heater will provide some safety net for that possibility. You also want a built in BMS (battery management system) to protect the battery during charging and discharging.

Lithium gives linear power (current) down to it’s last usable current. If it says it has 100 amp hours, you will get down to ~2%-5% of that at a minimum of 13.3 volts. AGM & flooded batteries power drops during discharge and just while sitting unused, lithium’s loss during storage is negligable.

There are many brands out there now to choose from. I purchased from Battle Born. 10 year warrantee, built in bms, now you can buy them with built in heaters and you should get anywhere from 3,000 to 5,000 complete discharge/recharge cycles before deteriorating capacity. They have done a great job in building that industry and educating us consumers.

 

[garageguy]

Don't forget to put a little wind turbin on the roof.
Could also charge batteries while rolling down the road.

 

[wisco-mb]

Heckler gave some really good info. There's some good articles and blogs out there, but just needs some time to research it.
I installed 2 qty 100W panels flat on my sled trailer. I have a EPEVER MPPT 30A solar charger. With 2 panels, I did not have enough sun to keep the batteries trickle charged during winter. I believe this was due to panels being flat, low sun angles in winter, low sun in winter, and snow. I do have some current consumed while parked, but not a lot.
I have the same setup on my camper, but only 1 panel. I switched the 3rd panel between my trailer and camper to see if it would help during the winter. It did not!
The 3rd one is one I can adjust the angle on. However, I need to get a ladder to angle it.
I believe the best method is to use two panels, and put them on a 12VDC actuator switch for tilting when parked. When I need to move it, turn the panels down. Future project of mine for the sled trailer.
So for winter, you cannot rely on solar efficiently. Need to be plugged in or generator.

I run 2 qty Duracell Deep Cycle Golf Cart Batteries, 235AH each. These are 6V and I run them in series. I bought these back in 2019. Still running strong. With one 100W solar panel on the camper, I have enough run time for camping weekends. Even with the Atwood furnace running on the colder fall days. Just barely gets me by on those.

I started looking at Lithium, but very expensive and the cold weather risks were a turn off. If only using during the warmer months, some very good advantages. I'll probably revisit them in the next couple years when I need to replace my batteries. Maybe prices will come down a little

 

[heckler56]

Heckler gave some really good info. There's some good articles and blogs out there, but just needs some time to research it.
I installed 2 qty 100W panels flat on my sled trailer. I have a EPEVER MPPT 30A solar charger. With 2 panels, I did not have enough sun to keep the batteries trickle charged during winter. I believe this was due to panels being flat, low sun angles in winter, low sun in winter, and snow. I do have some current consumed while parked, but not a lot.
I have the same setup on my camper, but only 1 panel. I switched the 3rd panel between my trailer and camper to see if it would help during the winter. It did not!
The 3rd one is one I can adjust the angle on. However, I need to get a ladder to angle it.
I believe the best method is to use two panels, and put them on a 12VDC actuator switch for tilting when parked. When I need to move it, turn the panels down. Future project of mine for the sled trailer.
So for winter, you cannot rely on solar efficiently. Need to be plugged in or generator.

I run 2 qty Duracell Deep Cycle Golf Cart Batteries, 235AH each. These are 6V and I run them in series. I bought these back in 2019. Still running strong. With one 100W solar panel on the camper, I have enough run time for camping weekends. Even with the Atwood furnace running on the colder fall days. Just barely gets me by on those.

I started looking at Lithium, but very expensive and the cold weather risks were a turn off. If only using during the warmer months, some very good advantages. I'll probably revisit them in the next couple years when I need to replace my batteries. Maybe prices will come down a little

Your results don’t surprise me. Are your solar panels in series or parallel? Check out Bogart Engineering’s discussion on mppt vs pwm solar controller. The polarity of opinions is comparable to “what brand oil is best”

 

[wisco-mb]

Parallel. One of the downfalls of that configuration, is if you have one shaded, it vastly affects overall output.
I get around 7amps output facing the sun in March with 3. I get that same amount with one in summer.

 

[bayfly]

While quite pricy, it seems the lithium batteries give me the ability to remain off the grid for several days only running the generator to recharge the batteries periodically. That’s all I am trying to accomplish right now. Wisconsin-mb’s comments confirm what I have read concerning winter use of the solar panels. Thank you for the comments and great information. I have so much more to learn on this but you have helped tremendously.

 

[heckler56]

Parallel. One of the downfalls of that configuration, is if you have one shaded, it vastly affects overall output.
I get around 7amps output facing the sun in March with 3. I get that same amount with one in summer.

You might consider buying a cheap Renogy or other brand PWM controller and see what difference in winter it makes. It will provide a constant state of charge vs mppt which is a on/off pulse and the low winter sun might confuse it further. Renogy has a pwn for $20 right now on sale, it might make difference

 

[wisco-mb]

You might consider buying a cheap Renogy or other brand PWM controller and see what difference in winter it makes. It will provide a constant state of charge vs mppt which is a on/off pulse and the low winter sun might confuse it further. Renogy has a pwn for $20 right now on sale, it might make difference

Good thoughts, thanks! I might try it out for that price!

 

[Hamilton]

Solar power can definitely be beneficial for off-grid adventures like ATV trips. A 100 watt rv solar panels should handle your needs for LED lights and device chargers. Consider expanding battery capacity if you plan to run the fridge and furnace fan frequently. It's all about finding the right balance between solar, battery, and generator use.