Semi-Permanent Off Grid RV solar charging

[rhody605]

Back story- Our family has 10 acres along the pembina river. Remote access, no chance for any services for the foreseeable future. Over the years we have made ourselves some campsites and this year I got a large trailer that we have kept there most of this summer.

I have currently have 2 6V batteries in the trailer. Worked great for most of one weekend with heavy battery usage. Radio lights, using the inverter for misc things (Ice maker, pellet smoker) and such. We have to use the generator in the mornings for coffee maker and breakfast, and occasionally during the day. At the end of the long weekends the batteries are too low. I'm adding another 2 6V batteries this weekend. which will help.

Onto the questions....

I want to setup 200W of solar for charging the trailer. This amount is affordable for now and I want to possibly expand it in the future.
Are the MPPT charge controllers worthwhile in the long run?

What's the max distance the panels can be from the charge controller, or the charge controller from the batteries? The best spot for the panels for light exposure is about 50-100ft from the trailer.

Was thinking could trench conduit from camping spot to panel area.

 

[blubbles]

That distance definitely isnt too far, but you will need to be calculating in the voltage drop and current requirements for the cable thickness as you go. 200W really isnt very much power nowadays, id suggest looking at much more than that if you are going to bother with it. You should be paying around 50-55C/Watt for your panels. I bought 315W panels for $135ish a few months ago (that being said this supplier is a POS lately and hasn't been responding).

What you have to realize is you are normally only going to get about 60% of the total capacity. Alberta's light isnt great most times of the year, and as the panels heat up they loose efficiency. So you really want to go a bit overkill on the panels or you will likely be disappointed.

MPPT are the only way to go. PWM controllers are at best 60-70% efficient. This is a lot to lose right off the top. MPPT are very reasonable now, I have had very good success with EPEVER brand ones, Tracer AN/BN. If you are buying a charger, id suggest going with a 40A. Lots of people will go smaller, but the price difference between a 30A and a 40A isnt much and it will give you some room for growth. Also many people calculate everything based on the maximum power output of these panels, but the better way is often to over panel a bit to the controller knowing that it won't really hit this ever. EG 40A theoretically needs 480W to hit 40a, id suggest putting 600ish W on it.

I can talk about this stuff for days, feel free to PM me if you have questions. Built many of these setups for friends and an instrumentation tech by trade, so ive dealt with lots. Costs have come down, I put 550W on my trailer a few years ago all in with cable, disconnects, remote displays, controllers, panels for right around 600 bucks.

 

[ABMax24]

I'd run a couple 300ish watt panels in series to keep amperages low and decrease wire size though the conduit. 600 watts of panels will still give you a reasonable chance of keeping your batteries charged during cloudy weather.

MPPT is a must, personally I'm a fan of Victron Energy controllers, but you pay a premium for them over the Chinese branded counterparts. A SmartSolar 100/50 would suit 600 watts of panels well, but that controller is $400 alone. The charge controller should be mounted as close to the batteries as possible, the panels can be some distance from the controller especially in this case as the solar panels will be outputting about 65volts.

 

[ctd]

I've been running solar in my fifth wheel sitting on 13 acres for several years. Original Concord batteries, 2ea 6v 22OAH, small inverter that runs all the entertainment & fridge on occasion should I need to turn propane off. Also an overhead residential style large fan that runs quietly & moves a lot of air runs on the inverter......avoids needing the AC.

Sadly I've had to run the AC a lot this season, normally I would hardly ever need the Gen.

Boggart Engineering is my charge controller & battery monitoring system, visit their web site if you are looking for good solar information. Charging the batteries correctly to get full capacity & long life, as mentioned sizing the wire correctly everywhere in the system is key. The Boggart site will help with that.

The charge controller is 30ah, you can add a second if ever needed. I've stayed with 12vdc panels that are 160watt each for a total of 320watt. Some of my reasoning staying 12v with panels wired in parallel is that it minimizes shading of one panel that lowers the overall output. Or if one panel should fail whatever I still will get full output from the other, no need for MPPT.

If we have any sun I rarely see under 90% during the day & generally the batteries are @ 100% most of the day. Occasionally we go below 80% & rarely 70%.

When these deep cycle AGM's fail I will most likely replace with Lithium for several reasons. Nearly 100% usable power vs 50% of a AGM or wet battery. If you understand the recharge of a AGM or wet battery, it's painful & slow done correctly, Lithium charges very quickly.

 

[rhody605]

Perfect responses guys!!

The main idea is to recharge the system while we are away. But at this rate the family wants to be out there more and more. So if I plan and prepare now, everything will be much easier to setup.

I've also heard really good experiences so with Renogy brand MPPT controllers and panels. Panels are a bit pricy but the 40A controller is only $170 on amazon.

What is the max input voltage for these controllers? Does it vary between the controllers?

 

[Rene G]

I've been running solar in my fifth wheel sitting on 13 acres for several years. Original Concord batteries, 2ea 6v 22OAH, small inverter that runs all the entertainment & fridge on occasion should I need to turn propane off. Also an overhead residential style large fan that runs quietly & moves a lot of air runs on the inverter......avoids needing the AC.

Sadly I've had to run the AC a lot this season, normally I would hardly ever need the Gen.

Boggart Engineering is my charge controller & battery monitoring system, visit their web site if you are looking for good solar information. Charging the batteries correctly to get full capacity & long life, as mentioned sizing the wire correctly everywhere in the system is key. The Boggart site will help with that.

The charge controller is 30ah, you can add a second if ever needed. I've stayed with 12vdc panels that are 160watt each for a total of 320watt. Some of my reasoning staying 12v with panels wired in parallel is that it minimizes shading of one panel that lowers the overall output. Or if one panel should fail whatever I still will get full output from the other, no need for MPPT.

If we have any sun I rarely see under 90% during the day & generally the batteries are @ 100% most of the day. Occasionally we go below 80% & rarely 70%.

When these deep cycle AGM's fail I will most likely replace with Lithium for several reasons. Nearly 100% usable power vs 50% of a AGM or wet battery. If you understand the recharge of a AGM or wet battery, it's painful & slow done correctly, Lithium charges very quickly.

I’ve looked into lithium batteries, they’re pretty awesome. I was going to recommend going with lithium as well.

 

[Rene G]

Perfect responses guys!!

The main idea is to recharge the system while we are away. But at this rate the family wants to be out there more and more. So if I plan and prepare now, everything will be much easier to setup.

I've also heard really good experiences so with Renogy brand MPPT controllers and panels. Panels are a bit pricy but the 40A controller is only $170 on amazon.

What is the max input voltage for these controllers? Does it vary between the controllers?

Where are you on the Pembina? I have family that live really close to the Pembina

 

[blubbles]

Perfect responses guys!!

The main idea is to recharge the system while we are away. But at this rate the family wants to be out there more and more. So if I plan and prepare now, everything will be much easier to setup.

I've also heard really good experiences so with Renogy brand MPPT controllers and panels. Panels are a bit pricy but the 40A controller is only $170 on amazon.

What is the max input voltage for these controllers? Does it vary between the controllers?

It will vary max input depending on the series for the controller. This will control how you are wiring it as well, if you are wiring them in series or parallel. Theres also a max input wattage depending on the series as well (Eg EPEVER Tracer AN can have less input wattage vs the BN) Which is extremely important if you are overpanelling.

Renogy is decent stuff, really they are probably all made in the same factory. Just whatever you decide make sure it has remote temperature sensors that can be pulled to the batteries. This is really overlooked by lots of people, but as temperatures change the charge parameters really do need to change as well. Being able to make custom charge setups is really worth it. This is also why its good to have the controller close to the batteries.

If it was me id start with a 40A controller and around 600W of panels. Id be putting a big conduit in for expandability, and put some extra strings in there for future pulls. Id be putting both panels wired in parallel not series if it was me. Costs a bit more on the cable, but helps if you get one panel being shaded etc.

In regards to batteries, Lithium has come really long way, but if you use it lots in the winter, realize that these batteries cant be charged below 0Deg C. This leads to lots of people wanting to put them inside, but I would avoid it if you can. All id be worried about the entire time is a Lithium fire. (Youtube has some amazing videos). Bang for the dollar its still hard to beat some lead acids right now. As the pricing comes down and the BMS systems get integrated heaters and such this will really change though.

 

[X-it]

Is all this knowledge from trial and error or just a lot of reading and research.

 

[blubbles]

Built a bunch of setups, learned some in school, and lots of research and courses to help design systems for industrial applications... Bit of everything?

 

[ctd]

Is all this knowledge from trial and error or just a lot of reading and research.

Solar has been in the bucket list for me, wanting to eventually be off grid. My 5fr has been a good why to learn prior to making the big plunge & live that life.

Unfortunately what I've learned is solar is not the end be all answer. It is awesome for the remote recreational property that is mainly summer usage.......heavy smoke negatively impacts the panel output.

 

[rhody605]

Where are you on the Pembina? I have family that live really close to the Pembina

We are about 15 mins north of drayton. On twp 512.

 

[Caper11]

The more panels the better on the roof, or mount one on a pole that will be facing the sun at the correct angle.
With a RV is not a matter of output wattage, but the surface area the the sun will reach. I have a 200w on the roof of my trailer, and I’m thinking of adding another for more surface area.
I have a smart charge controller in my trailer that has 4 charge modes.
A solar panel system will actually kill a flooded battery if the water level is not checked regularly.

My old trailer I had a older controller that gave as much power to the batteries as the system would output 100% of the time, if it was in the sun perfectly. I mounted a switch to shut off the solar system when I didn’t want it.

 

[Legend14]

If you have the river right there how about using a pelton wheel in the water?

 

[blubbles]

I am a big fan of use extra panels, so that you dont need to be perfectly situated in the sun at all times.

Depending on your setup (with MPPT) you can adjust the charge parameters to match your battery. Depending on brand even across all flooded lead acid batteries they differ from what they want them to float at, absorb at etc. My interstates equalize at 15.6, ive seen Rolls that want them at over 16V. I attached the one for Costco/Interstate to give you an idea of what to expect. MPPT is basically a fancy DC-DC controller, it constantly is adjusting the incoming to get the most available power, while outputting what is needed depending on the state of charge, like all smart chargers do.

Not to say that they wont use some water, but people who are going through consistently water ever few weeks typically are floating them too high (some converters stay constant at 13.8-14V).

Heres my panels, thats 550W on the roof. Ignore the bent TV antenna lol.

 

[rhody605]

If you have the river right there how about using a pelton wheel in the water?

The river is right there for sure. We have about 2500ft of river front.

We have thought about a water generator. There are a couple issues I think. The water level changes dramatically. About 6" per week lowers down this summer. After a hard rainfall can go up 1' in 2 days.

Other concern is theft or damage from people going by. Chances are low for sure. But have had damage on our beach area from randoms going by. Mostly just a damaged picnic table or fires on the beach, stuff like that.

 

[rhody605]

I am a big fan of use extra panels, so that you dont need to be perfectly situated in the sun at all times.

Depending on your setup (with MPPT) you can adjust the charge parameters to match your battery. Depending on brand even across all flooded lead acid batteries they differ from what they want them to float at, absorb at etc. My interstates equalize at 15.6, ive seen Rolls that want them at over 16V. I attached the one for Costco/Interstate to give you an idea of what to expect. MPPT is basically a fancy DC-DC controller, it constantly is adjusting the incoming to get the most available power, while outputting what is needed depending on the state of charge, like all smart chargers do.

Not to say that they wont use some water, but people who are going through consistently water ever few weeks typically are floating them too high (some converters stay constant at 13.8-14V).

Heres my panels, thats 550W on the roof. Ignore the bent TV antenna lol.

Have you had any worries about leaks in your roof? We still want to camp in a couple other places once or twice a year. If we change trailers how hard is it to remove and patch the holes?

 

[Legend14]

The river is right there for sure. We have about 2500ft of river front.

We have thought about a water generator. There are a couple issues I think. The water level changes dramatically. About 6" per week lowers down this summer. After a hard rainfall can go up 1' in 2 days.

Other concern is theft or damage from people going by. Chances are low for sure. But have had damage on our beach area from randoms going by. Mostly just a damaged picnic table or fires on the beach, stuff like that.

Yeah I don’t know much about it yet,you’d probably have to excavate a water box or something to control it,they are popular in BC and way easier to set up there,eBay seems to sell quite a bit of that equipment but I have no idea if the quality is good

 

[ABMax24]

It's not legal to alter a stream bed to install a hydro generator without appropriate permits etc.

 

[blubbles]

Have you had any worries about leaks in your roof? We still want to camp in a couple other places once or twice a year. If we change trailers how hard is it to remove and patch the holes?

Not really concerned about leaks, as long as you use good quality lap sealant and don't go crazy drilling holes there's not really any risk. If you look at the cables on mine they actually are routed down the back of the fridge vent, so there's not even any cable gland entries etc. The cables are eternabond taped down to the roof, there's no holes,

As far as moving them to different trailers, if you are dead set on moving them you can basically just unbolt them from their mounts on the roof and take the controllers out, id just leave the old mounts up there so there's no risk of leaks. But honestly with solar, normally you are better just leaving it on the trailer (you will get your money back when you go to sell it). Because by the time you are ready for a new setup, the panels will be better as well. Those panels are 275W/ea and a few years old. In that same size top of the line panels make 370W. The technology really is just getting better and better.

My trailer gets towed around 15-20 weekends a year, in the winter tons etc. Never had a leak, and dont expect to see any leaks as long as you are doing regular roof maintenance as you do with any trailer.