What is bare minimum solar for off-grid camping?

[ROBERT CROSS]

^
X3

We learned early to frugalize, the 63 Safari demanded it.
Our simple DIY system works well for us.👍
So far, 53ah is the most we have used in one day.
Bob
🇺🇸

[mrchinup]

Originally Posted by Piggy Bank

Guilty. I did not run the load calc. But I deduce that on a demand day--that is to say that it's camping weather and and I have need of the furnace--that it is also likely not a sunny day. This would then diminish the typical output.

If I didn't already own the generator I might be more likely to give it a go.
But I will keep my eyes out for product info, and read up.

Thanks

Just a heads up, most Interstate Deep cycle batteries won't charge correctly with a generator. So they won't last very long. 2 years is my guess. Most generators peak out at 14.4 volts, Interstates need over 15 volts in absorption phase. If you are just using a generator they have never been charged fully. http://www.cleanenergybrands.com/sho...Recommendation Then once a month you have to equalize the batteries. IMO, a good solar charger like this makes life much easier. It has bluetooth you can do everything on a smart phone.It takes seconds to program after you learn how to run it. Victron Smartsolar mppt 100/300 charge controller on ebay for less that 250 dollars.



Whether it's on the roof or on the ground I'd look for 30 volt panels you can use smaller wire if you want and have less energy loss. Very nice rig you have there, do it right the first time and save money in the long run. Panels are pretty cheap right now.



I have a tiffin right now Victron is used to keep my starting batteries full. I have a morningstar with 2 commercial 435 watt sunpower panels @ 72 volts to keep my house batteries full. Both have worked flawlessly. Batteries are over 5 years old AGM's and still charge up to 13 volts every night. Take care of your batteries and you will be a happier camper.



I had a 23 ft AS for 10 years, seriously thinking of going back to an older one. Right now we boondock about 6 months a year. Just my 2 cents good luck.

[uncle_bob]

Originally Posted by mrchinup

Just a heads up, most Interstate Deep cycle batteries won't charge correctly with a generator. So they won't last very long. 2 years is my guess. Most generators peak out at 14.4 volts, Interstates need over 15 volts in absorption phase. If you are just using a generator they have never been charged fully. http://www.cleanenergybrands.com/sho...Recommendation Then once a month you have to equalize the batteries. IMO, a good solar charger like this makes life much easier. It has bluetooth you can do everything on a smart phone.It takes seconds to program after you learn how to run it. Victron Smartsolar mppt 100/300 charge controller on ebay for less that 250 dollars.



Whether it's on the roof or on the ground I'd look for 30 volt panels you can use smaller wire if you want and have less energy loss. Very nice rig you have there, do it right the first time and save money in the long run. Panels are pretty cheap right now.



I have a tiffin right now Victron is used to keep my starting batteries full. I have a morningstar with 2 commercial 435 watt sunpower panels @ 72 volts to keep my house batteries full. Both have worked flawlessly. Batteries are over 5 years old AGM's and still charge up to 13 volts every night. Take care of your batteries and you will be a happier camper.



I had a 23 ft AS for 10 years, seriously thinking of going back to an older one. Right now we boondock about 6 months a year. Just my 2 cents good luck.

Hi

If you are going to charge your RV batteries with a generator, do not use the "charge" output from the generator (if it has one). There are a bunch of reasons for this. Simply feed the 120V output of the generator into the 120V input to your RV. Let the normal "shore power" charger handle the process. It will charge the batteries up just fine.

Bob

[Kristof]

An energy budget is the first step. Someone on here already quoted 85AH at 12V. That is nearly the mark I have.

The real trick is to think of the solar array as a generator. I am sure tour generator puts out 1000Watts or more. Off grid is a combination of energy storage and use, tank space, food storage and propane storage. If you sit down and figure it out based on time off grid you will see issues in one or more of those categories. Also remember it is not always sunny.

My fridge is an eco friendly off grid fridge with a danforth compressor. I have the numbers and it will draw 2.5 amps at 12V for the fridge and 2.5amps for the freezer. That is when you turn it on. After it cools down it only cycles on about once an hour so the total amp hour draw is way less than is reported. That is my main energy user.

We installed a hybrid array of 4 two panel sections that produces about 800watts in full sun. I have seen it produce 56 or so amps at 12V on sunny days, about half that in the shade and 10 amps in the rain believe it or not. We have decided not to bring the generator with us anymore.

Lead acid batteries die pretty quickly after you drain them below 50 %. There is a lot of chatter on the cost etc of LiFePO4 batteries but we have 400AH of a custom made battery. We run that and our systems at 24V and convert to 12 V for lights etc. We are also in Canada so the sun here is not as strong as down south.

At the end of the day if you want confidence for off grid camping you will need to go big. Our battery is about 5KW and our array is about 1KW. That seems to be about perfect and I would aim for something similar if you want the less stress and effort.

PS: Storage is key. A generator and outside panels have to be put away somewhere.

[drbrick]

We have 200watts on the roof and 180watts suitcase to follow the sun. These maintain two 6v trojan (210amps). We also carry a Champion 3400 duel fuel which we run on LP. All we do is boondock.

[HRTKD]

If you don't plan to install a full solar system and want to keep it simple, then use the "solar prep" ports and buy whatever system the vendor of the solar prep provides. The solar prep wiring is often minimal and can't support a whole lot of volts/amps that a full solar system (roof install) could provide. By going with the vendor's equipment you'll be assured of not overloading their solar prep. This is the easiest way that requires the least amount of solar/electrical knowledge.

Will it be enough? That depends. It will likely be plenty to run every 12 volt appliance in the trailer for a week. You won't get any 120 volt AC appliances from solar (microwave, air conditioning, etc), but that's what you have the generator for.

The reason I recommend the solar prep's vendor's solar package is that my research has shown that just about any aftermarket rooftop solar install is going to be too much for the wiring that is included in "solar prep". Hardcore boondockers will want to put in new wiring from the roof to their battery compartment to handle the amount of power that a good set of panels (say four 200 watt panels) can provide.

[Jim Foster]

I installed 250 watts of solar and two group 29 AGM batteries. On our ‘83 27’ Excella. I also changed to LED interior lights. I installed a 350 watt sign wave inverter to run the TV, Sat box and my CPAP. I carry a Honda 2000 for espresso maker and microwave.
When dry camping, batteries are usually recharged by early afternoon. When stored, batteries are always up and ready to go.
Very happy with this setup.

[mrchinup]

Originally Posted by uncle_bob

Hi

If you are going to charge your RV batteries with a generator, do not use the "charge" output from the generator (if it has one). There are a bunch of reasons for this. Simply feed the 120V output of the generator into the 120V input to your RV. Let the normal "shore power" charger handle the process. It will charge the batteries up just fine.

Bob

My diesel generator came with the rig already wired up. But that is the way it is wired, my converter would charge the batteries if needed. Before I put the panels up I used it once. The only time I start it now is to keep the generator in good shape. Thanks!

[Airlock]

I have 2, 6 volt, 224 amp hrs Sun Cycle AGM batteries on our 2019 16' Bambi Sport. I am able to keep the batteries topped off with a Zamp 140V suitcase solar set up. It is able to keep up with all of the things onboard that use 12V DC power. The only rate limiting factor is the capacity of our water and black/grey tanks (23gal). Zamp panels are expensive but the AS come prewired for Zamp and they are quality units. These suitcase units also work well to keep your batteries in top shape when not on the road too.

[Justinfinity]

It's intriguing to see all this advice, yet almost no comments about how critical the Charge Acceptance Rate (CAR) of your batteries is.

It does not matter whether you have 100W or 1,000W or 10,000W of power from your charge source (whatever that may be).

If you have conventional lead acid or AGM batteries, their Charge Acceptance Rate will behave in roughly the following manner:

(1) from 50% to 85% they will charge in BULK relatively quickly, accepting a high amperage;
(2) from 85%, their CAR will decline continuously and the time to charge in ABSORPTION to 100% will take several times longer until they get to FLOAT.

If you skip the ABSORPTION, you conventional Lead Acid / AGM batteries will sulfate and die.

If you have batteries with a high CAR, such as LiFePo4 batteries, they will accept a very high charge current and will charge fully to 100% very quickly.

Don't expect to get any reasonable amount of current from your 7-way connector; it's very low current and will probably require many hours of driving to get the batteries to 100%, regardless of the battery chemistry.

Whatever the charge source (solar, generator, shore power, vehicle alternator), you need a high current and batteries that can accept the high current in order to be self sufficient.

I have posted on this topic several times, describing my setup:
1. 6x100 solar panels, Victron MMPT controller
2. heavy duty custom installed umbilical 2/0 gauge welding cables (controlled by a relay) from tow vehicle dual alternators to AS using Victron Cyrix-Li controller.
3. 2 x 200A LifeBlue Batteries

Questions?