Designing a solar system

[TouringDan]

Originally Posted by uncle_bob

If you camp in the shade a lot, generators are a better bet. If you camp in the part of the world where there are few trees, it's a great thing. I doubt anybody always is in any one situation.

Starting with portable is cool. Expanding a portable system gets problematic. The total cost of "getting to the destination" is probably highest if you go through the portable route and wind up with rooftop.

Bob

We like to camp in the shade and if there is a generator free zone there, as in Cade’s Cove in the Smokies, then we are in it. In this case you need enough batteries and you need to be frugal in your electrical consumption. We only used about 10 amp-hours per day when we camped there for a week back in June.

I don’t understand how the total cost of solar goes up if you switch from portable to roof top. You are just moving the panels- same panels, solar controller and wire.

Dan

[alano]

Portable systems typically use PWM solar chargers, not the more efficient and more expensive MPPT chargers. Portable systems typically don't include a battery monitor. Portable PWM solar chargers may not be sufficiently rated to handle additional roof expansion should that be considered. Your portable PWM charger may not be compatible with lithium batteries should that be in your future.

Portable systems may be just fine for you, but when you plan ahead for the future you might not reuse all your portable components when designing a roof-top system.

[TouringDan]

Originally Posted by alano

Portable systems typically use PWM solar chargers, not the more efficient and more expensive MPPT chargers. Portable systems typically don't include a battery monitor. Portable PWM solar chargers may not be sufficiently rated to handle additional roof expansion should that be considered. Your portable PWM charger may not be compatible with lithium batteries should that be in your future.



Portable systems may be just fine for you, but when you plan ahead for the future you might not reuse all your portable components when designing a roof-top system.

I did my homework when I designed my portable solar system. I have a battery monitor and an MPPT controller. I just didn’t install my solar panels on the roof. All my components can be reused if I decide to install the panels on the roof.

Dan

[JMynes]

I have 200 watts on the roof, a Bogart SC2030 (PWM) charge controller, and a Bogart TM2030 battery monitor, using the factory pre wire.
All up cost was $756 and change, including wire, MC4 connectors, 30A breaker, nuts and bolts, VHB tape, Sikaflex, and aluminum to make the mounts. Yes, I kept a spreadsheet of everything that went in it.
Labor was free, I had no idea what to pay myself.

[uncle_bob]

Hi

At the very least, you have portable mounts for your portable panels. You need roof mounts when you go to a preeminent install. Many people do portable with a "portable kit". In that case, the panels may be the wrong size to fit on top of the trailer ....

Bob

[solst1ce]

The advantage of having the ability to be constantly charging is a definite advantage. The problem I have is the limitation of acceptable roof space. I have a dometic rooftop air conditioner 2 fantastic fans already and a frozen original rooftop vent that I plan to remove and would like to replace with a fantastic fan as it is directly above th sitting area.
I'll measure again and see if relocating an existing fan would allow for sufficient room to add a enough panels down the center line of the roof to provide a minimum of 400W of solar capacity.
I don't think I'd consider a pre-packaged "suitcase" solar as I want to build in efficiencies such as MPPT controller and LiFPo4 batteries . The price of monocrystalline solar panels is a relatively small expense of a total solar system I hope to build, and to be able to easily add more solar capacity in the future without making my '65 airstream look like a lunar landing craft makes a freestanding solar array very attractive.

[TheGreatleys]

Porque no los dos? 🤷

I see no reason you have to choose between roof mounted and ground deploy panels. You can have both. Couple on the roof for constant charging, and a solar inlet to connect a portable ground deploy. You can even get the cheap suitcase without the charge controller and just use your on-board MPPT controller for everything.

[TouringDan]

Originally Posted by TheGreatleys

Porque no los dos? 🤷

I see no reason you have to choose between roof mounted and ground deploy panels. You can have both. Couple on the roof for constant charging, and a solar inlet to connect a portable ground deploy. You can even get the cheap suitcase without the charge controller and just use your on-board MPPT controller for everything.

I completely agree. I actually have four 100 amp panels. I could always wire two of them in series installed on the roof and run the #10 line down the vent pipe into the bathroom cabinet and then down into the battery area and then run the two lines in parallel to the Victron controller- one line from the two panels on the roof and one line from two panels (in series) on the ground. This way I will always have solar on the roof and can supplement it with 200 watts of ground solar if needed. Thank you so much for pointing this out. That is a great idea. Then you have the best of both worlds. I suspect that has something to do with the meaning of the foreign words that went over my head.

Dan

[TheGreatleys]

Originally Posted by TouringDan

I completely agree. I actually have four 100 amp panels. I could always wire two of them in series installed on the roof and run the #10 line down the vent pipe into the bathroom cabinet and then down into the battery area and then run the two lines in parallel to the Victron controller- one line from the two panels on the roof and one line from two panels (in series) on the ground. This way I will always have solar on the roof and can supplement it with 200 watts of ground solar if needed. Thank you so much for pointing this out. That is a great idea. Then you have the best of both worlds. I suspect that has something to do with the meaning of the foreign words that went over my head.

Dan

"Why not both?"

It's a meme. Like an inside joke, but everyone's in on it and nobody thinks it's funny, but we keep bringing it up because the recognition makes us feel less alone.

Is my millennial showing?

[eastendmary]

Hi,
I had 200w of flex panels installed last march for my winter in the desert. they worked all year until now...when I really need them. I am watching the charge coming in at really low amps, like 0.4. Today up to 1.4...but the charge on the batteries continues to drop. This morning I only had 53% charging. I am in the desert with no obstructions, tightened the connection to the batteries, but have no idea where else to even look.

Don't know how it's wired, Airstream of Las Vegas installed them, but wouldn't give me any info when I asked about how they work other than pointing me to the controller panel, and I can't find anything in the literature.

I need HELP...please ;-)
Mary

[lewster]

Mary,

It sounds like your panels are approaching their end. Unfortunately flex panels do not last far beyond a year, and some don't even make it that long. I have tried the all and have given refunds to all who had them installed over the last few years.

What type of controller do you have?

Thanks!

Originally Posted by eastendmary

Hi,
I had 200w of flex panels installed last march for my winter in the desert. they worked all year until now...when I really need them. I am watching the charge coming in at really low amps, like 0.4. Today up to 1.4...but the charge on the batteries continues to drop. This morning I only had 53% charging. I am in the desert with no obstructions, tightened the connection to the batteries, but have no idea where else to even look.

Don't know how it's wired, Airstream of Las Vegas installed them, but wouldn't give me any info when I asked about how they work other than pointing me to the controller panel, and I can't find anything in the literature.

I need HELP...please ;-)
Mary

[Shermy1987]

Originally Posted by TouringDan

Sounds like complete overkill to me. Seems like you’re going to be spending a ton of money on a huge solar power system with lithium batteries and an inverter. Do you really need that large of a system. We boondock and do fine with 2 golf cart batteries, 200 watts of solar and a 1,000 watt inverter.

Dan

Overkill? What you run and what somebody else runs is a different story. I installed a larger system than described and run a 120v fridge. The system I designed for myself is just the right size.

[Shermy1987]

Consideration on running panels in series should also be thought about. If all your panels are wired in series, one shaded panel will compromise all the rest.

[eastendmary]

Originally Posted by lewster

Mary,

It sounds like your panels are approaching their end. Unfortunately flex panels do not last far beyond a year, and some don't even make it that long. I have tried the all and have given refunds to all who had them installed over the last few years.

What type of controller do you have?

Thanks!

Thanks for the response. My panels are relatively new...turned out the issue was a problem with the controller, can't remember the brand...sorry and not at the trailer now, but I rebooted the controller, had to unattach and then reattach the wires, which sounds easier than it was considering the location of the panel and the short wires, but...all good now. As the sun isn't so strong this time of year, it took several days to fully charge my batteries, but as of this morning, I was at 100% YEA!!!!