Help with Design for multi RV charging setup

[OkanoganJim]

I need some help with designing a system. I have a building that is 99 ft long and has 7, 14 ft wide bays for storing RVs. I would like to build a system to provide 12-volt solar power to each bay for the purpose of keeping the stored RVs battery charged. The end of the building faces south and here is where I would like to mount the Solar Panels. To dip my feet in the water, I recently purchased 2 Coleman 100-watt Solar Panels with battery controllers from Costco. I am thinking I can buy 5 more and end up with one 100-watt panel for each bay, at least to start. I suppose the easiest design would be to run wires from each panel to each bay and then to the controller. But Since the building is 99 ft long, worried about voltage loss to the farthest bays. Wondering if there is a design that could have a main buss of two heavy gauge wires (like 6 gage) running through the bays and each bay would tap into it then to the battery controller. Something like a household circuit except its bening fed by 7 100-watt solar panels. If this is feasible, should the panels be wired in series or in parallel? If in series, would I need something to drop the voltage down for each bay, prior to the battery controller? Thanks for your help.

[sdold]

Hi Jim, welcome to the forum. Any chance you could just run a 15A AC circuit to each bay for a battery tender? It would be a lot simpler and cheaper in the long run.

[OkanoganJim]

I don’t have power to any of my buildings. Bringing in Power is a 10-15k investment for me. I am wanting to try this as an interim phase to get by for a few years, or maybe if it works fantastic, that will be all I need. I guess I should have mentioned this in my post.

Thanks

Jim

[SunEagle]

First I would do what sdold state by running grid power to that building.

If that is impossible (I do not mean expensive because solar is much more then a grid run, I mean impossible) I would look into a charging system for each RV bay involving panels, CC and batteries. For you to run all of the charging from a single battery point would require very big wires as well as an increased cost for the system.

No one said a solar/battery system was cheap and easy. So unless you just want to be cool and spend a lot of money find a way to get grid power to that building.

[OkanoganJim]

Well who doesn't want to be cool. But to bring in Grid power, I need to open up a road, ditch in Primary power, purchase a Grid transformer, then since this is Commercial, pay an electrocution to setup a meter and a service, and wire each bay. My RV which is inside the building has a solar panel on the roof that maintains the battery. Only problem is, its now inside. So this is my inspiration for trying to design this system. This building will store RVs, so only a maintenance level of charge is to each bay during daylight hours is what i am trying to achieve.

[Mike90250]

Does the roof have a good angle and view of the sky for direct sun in all seasons ?

if so, here's what I'd do.

a) 100w panel on the roof, extend wire to a J box with fuse and Anderson connector (female)
b) install a simple PWM charge controller INSIDE the RV to be charged, and wire the BATT terminals to the battery to be charged (fuse this also)
c) install a Anderson connector near the drivers side front grill, connected to the PV input of the controller (female)
d) get a neon colored electrical cord from wally world and install male Anderson connectors on both ends.
e) drive the RV in, connect the colored cord to the RV and solar Jbox. One RV is now charging when the direct sun hits the PV panel.

Lather, rinse, repeat as needed

https://www.andersonpower.com/us/en/resources/PowerPoleResourcesPage.html

and

https://www.andersonpower.com/content/dam/app/ecommerce/product-pdfs/PP30-P-S/ds-pp30ps.pdf

[littleharbor]

Even if you have to tilt the panels with a couple legs I'd say put each individual panel directly over each bay. The shorter the wiring, the better. Also the closer to the battery to the CC the better.

[SunEagle]

Well who doesn't want to be cool. But to bring in Grid power, I need to open up a road, ditch in Primary power, purchase a Grid transformer, then since this is Commercial, pay an electrocution to setup a meter and a service, and wire each bay. My RV which is inside the building has a solar panel on the roof that maintains the battery. Only problem is, its now inside. So this is my inspiration for trying to design this system. This building will store RVs, so only a maintenance level of charge is to each bay during daylight hours is what i am trying to achieve.

As I and others have stated. It would be less expensive and more resilient to have a solar panel and charger for each RV bay. Since you only need a trickle charger a 100watt panel should be enough. But you still need to run either the generator or engine to get the coach batteries back up to 100% SOC and stir up the fluid to keep them around as long as possible. A trickle charge will just keep them up but it is not good to keep them that way for long.

[OkanoganJim]

Thanks for all the great replies. The ridge of my roof runs north-south but the angle is not all that steep. This is a metal building. The simple idea of putting a panel on the roof over each bay is a good one. I will get to thinking about making a roof mount for the two panels I have.

[J.P.M.]

Thanks for all the great replies. The ridge of my roof runs north-south but the angle is not all that steep. This is a metal building. The simple idea of putting a panel on the roof over each bay is a good one. I will get to thinking about making a roof mount for the two panels I have.

I haven't seen any mention of system duty yet. How much energy do you expect all this PV to provide over a year's time? PV systems are usually sized to meet all or some portion of a load, particularly off grid systems that tend to be expensive in ways beyond initial $$ cost. Depending on how many of what may wind up being a number (how many ?) independent systems, get set for a part time job maintaining them.

If you're looking for help with system design, my respectful suggestion, if you haven't done so already, is to start system design by specifying a system duty.

Add the cost of generator backup to the PV costs.

Also, do you have any building codes or permitting to contend with ?

[PNW_Steve]

I haven't seen any mention of system duty yet. How much energy do you expect all this PV to provide over a year's time? PV systems are usually sized to meet all or some portion of a load, particularly off grid systems that tend to be expensive in ways beyond initial $$ cost. Depending on how many of what may wind up being a number (how many ?) independent systems, get set for a part time job maintaining them.

If you're looking for help with system design, my respectful suggestion, if you haven't done so already, is to start system design by specifying a system duty.

Add the cost of generator backup to the PV costs.

Also, do you have any building codes or permitting to contend with ?

It sounded to me like OP simply wants to float the batteries on stored RV's.

There is a product out there called "battery tender" or "battery minder". I forget which but a little Google Fu should turn it up. The US Army uses them to keep batteries up on vehicles parked long term. They make a 12v version as well. IIRC: they use an 80watt panel.

[J.P.M.]

It sounded to me like OP simply wants to float the batteries on stored RV's.

There is a product out there called "battery tender" or "battery minder". I forget which but a little Google Fu should turn it up. The US Army uses them to keep batteries up on vehicles parked long term. They make a 12v version as well. IIRC: they use an 80watt panel.

That may well be. If so, and depending on particulars, meeting the duty with an off grid PV solution, while having cachet and a gee whiz factor, may not be the overall best way to meet the as yet undefined duty.

If it's simply a float operation for batteries, and nothing or not much more besides a light or two, a phone and a laptop, etc., depending on that duty, seems to me that a small ice powered generator would be less $$ by about an order of magnitude, and a lot less hassle as well.

Still, whatever the duty (= output requirements and patterns), that load is usually a required input for the design of any system, on or off grid.

Maybe the OP came here unaware of the costs in treasure, time, and toil required to obtain and maintain an off grid system.

Posters coming here with not much more than good intentions and the rose colored glasses outlook that's been imparted to them by their own uninformed wishful thinking and by peddlers and the greenwash media pushing the idea of PV as simply an always cost effective plug/play no brainer is not uncommon and seems to me has happened before around here.

An ICE generator solution may not be simple as an extension cord and some fuel, but it's probably less complicated than off grid PV and a whole let cheaper and easier to maintain.

It'll most likely be needed anyway for off grid applications. Get one that's appropriately sized for the duty, Spring for a knowledgeable, licensed electrician to wire it in, and maybe add the PV one bay at a time or other increment after learning the possibilities and limitations of PV from a reliable source, and then see how it goes.

[NCmountainsOffgrid]

as an RV owner, a diesel motorhome, and having 'stored' my RV several times, my question would be 'why' are you wanting to provide 12v power to these bays, if I get that you are using these as 'rv storage' for patrons.... ?

[PNW_Steve]

as an RV owner, a diesel motorhome, and having 'stored' my RV several times, my question would be 'why' are you wanting to provide 12v power to these bays, if I get that you are using these as 'rv storage' for patrons.... ?

I suspect that it is for the same reason many of us connect an external 12v source every Winter. To keep the batteries charged.

It seems that I am the only one who thinks OP has a good idea. I have stored my RV's in places with no 120v power. A generator would NOT be a practical solution. The first year I stored without power I destroyed a set of batteries. The next year I threw an 80 watt panel on the roof and a PWM controller to keep the batteries. Worked great for me.

Something like this: https://www.amazon.com/Battery-Tende...omotive&sr=1-7 along with a 50watt panel for each bay.

[SunEagle]

I suspect that it is for the same reason many of us connect an external 12v source every Winter. To keep the batteries charged.

It seems that I am the only one who thinks OP has a good idea. I have stored my RV's in places with no 120v power. A generator would NOT be a practical solution. The first year I stored without power I destroyed a set of batteries. The next year I threw an 80 watt panel on the roof and a PWM controller to keep the batteries. Worked great for me.

Something like this: https://www.amazon.com/Battery-Tende...omotive&sr=1-7 along with a 50watt panel for each bay.

While I agree that keeping the coach batteries topped off and happy there are a number of ways to do it.

I use to have my RV in an open storage place so needed to run the generator or main engine to get the batteries recharged. Not the cheapest way but a small solar trickle charge should work provided the batteries get enough