Comparing Solar Systems

[D_E_Bishop]

I know this has been asked before! Yes I have found some great info in the archives, no I haven't found the answer I need.

My question is;

If currently we can go three days of dry camping(Hi Jolly for example) in the spring or fall, not needing to charge the batteries. Our rig is a 32 foot Adventurer with mostly LED lighting, most video stuff is 12vdc, TV is 120vac(requires using inverter), used maybe 2.5 hours if we watch a movie, normal draw for water heater and fridge and using a boombox on 12vdc maybe 2 to 3 hours a day instead of watching TV.

To extend our stay for a few more days, or indefinitely without using generator or engine to charge batteries, roughly what am I looking at adding. Of course I know there are tables to figure my average daily usage and I this is sort of cheating but would the general agreement be 2 GC2 batteries or will 4 batteries be absolutely necessary. How many panels totaling how many amps.

It is not going to be cheap to add two more batteries, the Adventurer is somewhat short on exterior storage and there is no room whatsoever in the understep battery compartment. While I have no problem installing the panels on the roof(there is a ton of info available from this site to help there) and wiring the new batteries if required or the panels and controller, I do not have the experience or equipment to weld together the steel to provide storage for the batteries.

This is my first foray into a real solar charge and maintenance system and I can do everything but the welding and it's not easy for me to sit down and fill out the estimating chart to determine what I will need. To be very clear it is a mental function I am not well equipped to do, I am severely dyslexic and get frustrated when faced with so many questions and need to remember things like how many hours a day we use appliances.

So if it is possible, how about some guesstimates to get me started on estimating costs, also what is a must read before I get too involved in this project.

TIA, d.e.bishop

[D_E_Bishop]

Currently we have two Interstate GC2's, not sure which AH rating, I think there are two different AH ratings available. Now that it is just the DW and me most of the time, I think we can go longer than three days but we normally don't dry camp where we need the AC. We seldom spend days in the RV, we like to explore and get out and around in the evenings. The DW likes to read at night and I surf some times so normally we don't have much going on. Additionally, I have converted all of our ceiling and reading lights to LEDs and I will be making a liquid tite fixture for use under the MV/Conv. Oven. If we watch movies, it is normally just one a day and we do have to use our 150watt inverter for the TV which draws 35 or 40 watts. The BluRay player is like 10 or 15 watts. We also have a small (5 or 7 watt) panel but even the manual from Winnie says it wouldn't supply enough to negate the parasitic draw. I have a Beltran 15watt solar battery minder that when we install the new system will be only used for the chassis battery, that will keep up with the parasitic draw for the chassis.

I'm going to go for a 250 to 300 watts and the two batteries we have now. Next week I should done with my part of the remodel of the S&B and will be able to go around to the suppliers around this area.

Thanks again Guys you are great.

[brulaz]

I don't know what type of batteries you can use space-wise.

But a high quality pair of 6V golf cart batteries might help out a lot.

Trojan T105RE are 225 Ah (20hr rate) batteries that can go down to 80% depth of discharge (DOD) over a 1000 times, according to Trojan docs. That's 0.8x225=180 usable Ah.

How many times a year will you need to use 180Ah before full recharge? You will be able to do that 1000x, before needing to replace the batts.

Coupled with a few hundred watts solar, you will be in very good shape.

[Mel_B_]

Check out renogy.com they have some great deals on solar kits, takes alot of the guess work out of the picture. While on line looking at the kits, call tech support and explain what your using and they will help you. I just installed the Renogy 400 watt eclipse premium kit with a 40 amp charge controller. And my batteries are 4 6 volt 120AH golf cart batteries (FLOODED)
Also bought a 2000 watt inverter/charger from renogy. Little big for most people but we spend summer months on our off grid property in Washington near the Canadian border, I own 3 different GENS. But I'm hoping the only time I need to run one now is if we have a long stretch of bad weather or we want to run the AC.
Mel

[TexasChaps]

time2roll wrote:

TexasChaps wrote:
"So a very simple rule can be applied 1 Watt of panel, to 1 AH of battery, to 1 watt of Inverter."

Depending on use that seems like a small inverter.

true, but the engineer who stated that was designing for long term reliability on solar radio installations etc. for RV use we might use a bigger inverter but for shorter periods of time.

the key issue is not to over stress the batteries. so limiting the charge and discharge current will increase lifespan..

[time2roll]

TexasChaps wrote:
"So a very simple rule can be applied 1 Watt of panel, to 1 AH of battery, to 1 watt of Inverter."

Depending on use that seems like a small inverter.

[Fubeca]

atperci wrote:
We have a 32 ft Fleetwood Encounter with 6 of us. With kids, everything gets more use, lights are left on, water is used more, more than one tv is on at a time (running off one 300 watt inverter), electronic devices that have to be charged, etc.

We have 400 watts of solar and only 2-6 volt batteries. We've gone 5 days with no generator usage in summer time at the beach and only running out of fresh water and waste water space.

We live near Silicon Valley where there is no shortage of cheap supplies of solar panels, I think you can find similar deals down in your area, too. I pieced together and installed the system myself for under $500. The Tracer MPPT 30A controller I'm using is not perfect, but it gets the job done, it's reported up to 24 amps into the at and has them topped off by early afternoon in most instances.

I would say that if you don't have any really large draws on your batteries, such as a big inverter, you should be fine with just your 2-6 volt batteries. Especially considering you're already getting 2 to 3 days out them as it is.

We are in a similar situation with a slightly smaller trailer. We have 2 245W panels and an MPPT controller. We use between 30 and 70 AH a night and always are fully recharged if there is sun (usually before mid-day). We can go indefinitely with our 2 6v batteries unless it is a week with no sun. We use fans, lights, chargers, without any real effort to ration power.

[TexasChaps]

here is an informative article on solar/RV

https://www.solarpaneltalk.com/forum/off-grid-solar/12v-solar-for-rv-or-camping-etc/21436-12-volt-de...

the author does suggest :-

"So a very simple rule can be applied 1 Watt of panel, to 1 AH of battery, to 1 watt of Inverter."

however, in reality your panels will only be at full output during
peak hours and then only on a good day for at best 6 hours or so..

so you will need to size panels to recharge the batteries in this time.

[atperci]

We have a 32 ft Fleetwood Encounter with 6 of us. With kids, everything gets more use, lights are left on, water is used more, more than one tv is on at a time (running off one 300 watt inverter), electronic devices that have to be charged, etc.

We have 400 watts of solar and only 2-6 volt batteries. We've gone 5 days with no generator usage in summer time at the beach and only running out of fresh water and waste water space.

We live near Silicon Valley where there is no shortage of cheap supplies of solar panels, I think you can find similar deals down in your area, too. I pieced together and installed the system myself for under $500. The Tracer MPPT 30A controller I'm using is not perfect, but it gets the job done, it's reported up to 24 amps into the at and has them topped off by early afternoon in most instances.

I would say that if you don't have any really large draws on your batteries, such as a big inverter, you should be fine with just your 2-6 volt batteries. Especially considering you're already getting 2 to 3 days out them as it is.

[Boon_Docker]

Seeing as you can go 3 days now (without solar) I would go with two 6 volt GC-2 batteries and 300 watts of solar. Plus buy a Champion 2000 inverter generator for back up just in case it is cloudy for days on end and for using the microwave.

[corvettekent]

BFL13 wrote:
Please clarify the three day limit now--is that when, even with the solar on nice days, your battery runs down as far as you want to let it get down to?

-double the battery bank and keep the same solar, add some solar, or do both.

Or, is that because in Spring and Fall it hardly ever goes more than three days of nice days for solar, and the battery runs down in cloudy conditions?

-more solar won't help much if any when solar conditions are poor. Add battery and run the gen to power the battery charger until the sun comes out.

I believe the OP does not have any solar yet.

[red31]

D.E.Bishop , if I assume you have 2x6v already and you get em down to 50% in 3 days, that's about 30-40 amp hrs a day.

daily irracianc multiplier for time of year/tilt/direction
http://www.solarelectricityhandbook.com/solar-irradiance.html

I use "4" (spring/fall flat)

40 ah/day / 4 (hrs/day!) = 10 amp panel. 10A * 18v = 180 watts of solar to extend, double or triple for full time!

[CA_Traveler]

If you then need to add batteries and welding plan it out. Cut the metal etc and screw it in place as needed for the new batteries - ie use sheet metal screws etc. Then go to a welding shop and it will be minimum cost as there is no setup. You may need to first cut out prior battery supports.

You will need to completely disconnect ALL batteries and solar before welding.

BTW Label and take pictures of all wiring before anything else.

[TheSidwells]

I just put in 3x160w panels and 2 additional batteries totaling 4x12v and a 2000w inverter so I can work full time from the RV. I left my go-power 30amp power controller and now regret not switching it out for MPPT. Once I upgrade to a MPPT I'll be set.

[CA_Traveler]

3 days is good and to extend that just add solar. I'd guess about 300W but allow for additions. Battery life and AHs can be improved with GC2s but it doesn't seem like you need them.

If you really want to get a handle on battery usage then install a battery monitor like the Trimetric. You'll then know your usage, battery charge state etc. This is an invaluable device for dry camping.