I love my RV solar system!

[chrisski]

A buck converter like that has the potential of very high efficiency and low idle
current, though it may need external filtering to avoid radio interference. Expect
the negatives of the two voltage systems to be directly tied together.

Thanks. I was looking at something like that, or maybe the same one, to run small DC bilge pump off a solar panel to stabilize the voltage at arounfd 12 VDC and not feed the 18 VOtls from the panel directly to it.

[chrisski]

I guess the RV with the 12 V starter battery would make things much easier. Going to 24 VDC is a future project, I've got to finish my 12 VDC setup first.

[bcroe]

Well the brakes of course would still be powered by the starter battery, which would still be 12 volts. But as far as the cabin lighting and things like that, I've had great luck with these: amazon.com/Daygreen-Voltage-Regulator

They're used on golfcarts (which are often 48v or 36v) to power 12 volt stereos and things like that. I haven't used that one specifically but I've used similar ones, they work great.

I wonder what other people have come up with for powering their 12 volt systems from a higher voltage battery bank. I wonder if you could simply tap into the batteries where they make 12 volts? In other words, just series two of the batteries for 12 volt appliances, but have them also wired for 24 volt for the inverter?

A buck converter like that has the potential of very high efficiency and low idle
current, though it may need external filtering to avoid radio interference. Expect
the negatives of the two voltage systems to be directly tied together.

Yes people talk about tapping into a lower voltage on the battery string, a good
way to damage them. But I am wondering if this might be fine on a limited basis
using one of those battery equalizers of sufficient capacity? Bruce Roe

[Wrybread]

I don't have the issue with brakes since mine is an RV, not a trailer, so I still have a 12 volt starter battery. So I could just use something like this for the cabin lighting etc:

https://www.amazon.com/Daygreen-Volt...9&sr=8-29&th=1

They're used on golfcarts (which are often 48v or 36v) to power 12 volt stereos and things like that. I haven't used that one specifically but I've used similar ones, they work great.

I wonder what other people have come up with for powering 12 volt systems from a higher voltage battery bank. I wonder if you could simply tap into the batteries where they make 12 volts? In other words, just series two of the batteries for 12 volt appliances, but have them also wired for 24 volt for the inverter?

[chrisski]

If you were to wire to 24 VDC, how would you power your 12 VDC in your RV? In my case, I have 12 VDC electric brakes on top of the 12 VDC appliances. I’ve thought about a 24 VDC to 12 VDC converter, but not sure if that would provide enough amperage with the brakes.

Happy for your success. Must have been a nice few months in quarantine.

[SunEagle]

It is great to hear about a success story when it comes to solar and RV living. I am sad to say my wife and I have gotten use to cool temperatures and need AC to do that. From what I have researched it is very hard to run an AC unit or any high wattage loads just using solar and batteries. So unlike you we go to sites that have a power hook up so we do not have to run our generator much at all. We may be temped to do dry camping in the winter but it will never happen in the summer without AC.

[Wrybread]

My girlfriend and I just finished 3 glorious months of full timing in our RV during quarantine here in Northern California. Our solar worked spectacularly as always. We don't have a generator and never start our engine, just 100% off-grid solar.

I work part time as a campground host and the campground was closed to visitors (a quarantine paradise, ha), but now that it's open again it's a sea of RVs with no solar panels on their roofs, and everyone running their generators on bright sunny days. They probably have battery banks anyway, which is the most expensive part, so it's downright crazy that they don't have solar panels too. It's a real shame.

I think part of the reason is all the misinformation out there about RV solar. People still have their expectations tuned to old style RV solar with sub 300 watt banks, PWM charge controllers and 12-volt panels.

Anyway, our solar system in a nutshell:

- three 300-watt 72-cell panels ("house style panels") in parallel to avoid shading issues (about $120 each). Flat mounted on our roof. I should clean the seagull poop off them more often.

- a Morningstar MPPT-60 charge controller (bought used for $200, new I think $400, but I previously had this cheapie and it worked just as well). If I was buying new I'd look closely at the Victron models for their excellent monitoring apps.

- 4 Trojan T-105 batteries, wired for 12 volt. If I was starting over I'd probably go 24 volt, but these have worked beautifully. They're 5 or maybe 6 years old now and still working great. Just keep an eye on your water levels. Some day these will die and I'll probably replace with lithium.

- Xantrex 1000 watt inverter, but their 600 watt model would be fine too.

We both work full-time in front of computers all day, she with a laptop and an external 23 inch monitor, me with a laptop and often a 21.5" iMac. And we run our RV's propane heater with it's power sucking blower whenever we need, which is most nights here on the Northern California coast, and lights and power tools (frequent grinder and orbital sander) etc. We literally never give a thought to power consumption. I wish I had watt numbers for this write-up but I never hooked up my Trimetric watt meter after getting this RV 5 years ago since I don't have to give much of a thought to power consumption anymore.

Here's the most recent log from our Morningstar charge controller:

panel.jpg So for anyone considering adding solar to their RV's, I couldn't recommend it any higher. It's dirt cheap and, if you get a few house style solar panels, an MPPT charge controller and sufficient battery bank, will be mostly set it and forget it. And if anyone tells you solar doesn't work well on an RV ask them about their system, I bet it will be some combination of panels that aren't permanently mounted, 12 volt panels, PWM charge controller, sub 300 watts of panels, etc. Or maybe they've never even owned an RV.

Solar is literally the best money you can spend on your camper in my opinion. And plus you won't be blasting your neighbors with a generator anymore.

I'm glad to answer any questions about my experiences if anyone is on the fence.