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barney_g · 08-18-2011, 11:26 PM

Hello everyone,

I have a '99 Itasca Suncruiser with the optional pathetic 10 watt solar panel for the house batteries.

I have provisions for 3 batteries under the entry steps and have put 3 12v deep cells there for boondocking.

I have 2 trips I take for about 10 days each annually where I don't have a hook up. I prefer not running the generator if I can avoid it. I'd like to be able to watch a couple of hours of TV each evening (while keeping my satellite DVR powered up during the day for recording purposes) and then have the house batteries completely recharged with a solar panel.

From what I've learned, I want a name brand panel (where the warranty will be worth a darn), same for a MPPT charge controller, and keep the wires large enough to avoid resistance and all the wire runs short.

Thinking of one Sharp 224 watt solar panel, and a good charge controller that will take good care of my investment in batteries. Maybe 224 watts is more than I need but, "I'd rather have it and not need it, than to need it and not have it." Besides, there will be cloudy days and days where I'll use more electricity than others.

I've read that you want to discharge a deep cell battery slowly and recharge them the same way. If I have 3 12v deep cells, would this arrangement recharge them too fast and thus damage (or reduce lifespan of) the batteries?

I'm open to any suggestions on panels and charge controllers. I'm really trying to keep things as simple as possible without redesigning the rig to accept a million batteries and panels and make the most of the provisions that already exist (that being battery storage). The wires should be pretty short as they only need to drop straight down a wall into the cavity under the steps.

I've heard that solar panels have come a long way from the old days and there are even diodes to allow for partial shading (say from the A/C unit etc).

Of course I don't have unlimited funds, so a reasonably priced combination goes without saying.

Any advice would be appreciated. Thanks

autofish · 08-19-2011, 12:37 AM

Barney I have 4 120 watt pannels and find this keeps my 4 6volt t105s charged up fine. They put out about 25 amps in full sun which is a good charge rate. I also run the tv about 4 hr, per night. hope this helps

KJINTF · 08-19-2011, 09:06 AM

That one large panel might cost extra to ship and more difficult to get installed

I went with two 135 watt panels - smaller and easier to get installed - they work great
Hooked them in series for a higher voltage about 40vdc thus less current - smaller wires and easier to install
Also went with a Tristar MPPT-60 controller - No fans or moving parts to wear out, ethernet interface, expansion for possible future panels, consists of three 20amp controllers in parallel only switches them on when needed to keep the efficienty up

Only problem is that we do not like campin in the sun - much prefer the shade

Everyone does it a bit different

barney_g · 08-19-2011, 01:39 PM

Autofish: Thanks for your input. How many days can you rely on your solar panels for TV?

KJINTF: My thought with going for the one larger panel was fewer holes to drill in my fiberglass roof. I hope to find a supplier nearby where I can pick it up directly so shipping shouldn't be a problem. Also, a good excuse for a trip ;-)

I also prefer to park in the shade if at all possible. Are you able to get any benefit from your panels from a shady spot?

Thanks for the controller recommendation.

bigskymt · 08-19-2011, 05:00 PM

Isn't the 224 watt a 24v panel?
Wouldn't you want to stay with a 12volt panel for charging your batteries?
We have four 6 volt and two 12 volt deep cycle in our bank and about 270 watts solar that supply 15-18 amps at full sunlight.
We arrive with all batts fully charged. Two weeks of dry camping with minimal use of microwave, hair dryer and coffee maker. 3-4 hours of TV per day and our batts never drop below 50-75%
If you do a search of "solar" on this forum you will learn a lot.

barney_g · 08-19-2011, 06:46 PM

bigskymt: Thanks for your reply. Actually it is a higher voltage than 24v. My plan was to make use of the new MPPT controllers so that is not a problem. This web site addresses it: Charge Controllers for Solar Electric Systems

Never thought I'd be able to use a microwave on battery power. Hmmm

bigskymt · 08-19-2011, 07:21 PM

Thanks for the link, good information. I like your idea with the larger voltage panel since you are starting out new everything.
I believe our microwave oven draws about 900 watts. Double that for convection which we only use with gen.
Coffee maker is about 950w.
We cut our TV current draw almost 50% with the LED flatscreen.
The biggest power draw is the furnace fan in cold weather. That coupled with less sunlight and more time inside draws a lot of current. On really cold mornings we start the gen. and use electric heaters for a couple hours or so.

barney_g · 08-19-2011, 08:05 PM

Yeah, but now wondering if maybe I should get 2 but don't know if the weak link is my storage capacity. I usually only camp when it's relatively warm but start the generator for my coffee maker and microwave, also to cool things off when I get back to the RV if it's hot, I'll turn on the AC units for a bit.

My "Fantastic Fans" are amazing. The RV can be cooking inside and I open the door and turn my 2 fans on and it's cool (about outside temp) in minutes. They probably draw a lot of juice though.

Did you get those wattage numbers from the labels or did you use something like "Kill A Watt?"

bigskymt · 08-19-2011, 09:59 PM

I would opt for as many panels as possible. On a cloudy day, shade, wintertime etc. you will need all the output you can get. Your controller will shut off when preset voltage is reached.
I read the specs for everything we plug in. We have only had hookups at a CG once in the last 11 years and my wife hates to disrupt nature with a gen. Consequently electrical efficiency is a must.
You may consider one panel and upgrade another if necessary.
If you think Fantastic Fans are GREAT, wait 'till you call the factory for support. They put most everyone to shame with their customer service. Current draw is low.

autofish · 08-19-2011, 11:02 PM

Barney My 4 120 watt pannels will keep up with our electric needs as long as the sun shines for 5 hrs or more each day. I also have a 2000 watt inverter so we use the batteries to make coffee and run the microwave some each day. We do run the gen set during the winter if there is not enough sun light. Never let the batteries go below 50% and as of now they are 7.5 yrs old and still going strong so I feel my 480 watt system works fine for my needs. hope this helps

BlauMax · 08-24-2011, 10:15 AM

I haven't explored using solar on my "new to me" MH. I had a couple of panels years ago with a 2K Heart inverter on my 5er.. this is going back 12 or so years. Seems to me I read the the inverters were pretty poor in efficiency. IOW, they used a lot of juice to keep them going before the actual use by appliances. (Maybe poor terminology on my part)

Has the efficiency of these units improved in the past dozen years? Are they likely at or above 90%..?

ralper · 08-31-2011, 04:42 PM

Batteries should not be charged at more than 10% of their amp hour rating.
I have 6 - 6 volt batteries. 675 amp hours. Charging rate 67.5 amps.
My maximum output from my 400 watts of panels is 28 amps which is only about 4%. This is reached rarely. So you can see that solar is only a trickle charge and will not over charge batteries if a good controler is used to stop charging when the batteries are full.

See my post under Boondocking. "Solar That Really Works"

jimbo16720 · 01-09-2012, 10:44 PM

I posted a website called solarblvd.com that sells panels pretty cheap. They have 2-80watt panels and a Morningstar MPPT controller for $429. It's in California and shipping to Pa. is only $35. Those are the best prices I found so far. Granted people that live in the western US get better deals because thats where most of the panels are sold.

okmunky · 01-09-2012, 11:29 PM

I have this system Amazon.com: 272 Watts Solar Battery Charger Kit for 12V batteries. Flexible Solar Panels PV Laminate, Charge Controller & MC Cables: Patio, Lawn & Garden with 2 deep cycle 12v batteries, which I want to swap out for golf cart batteries.

I can get thru even a very cold night using the propane furnace and only use 25% of the charge. And we run the LED TV for 5-6 hours plus LED lighting. These panels charge better in lower sunlight than rigid panels.

The kit does not come with much in the way of instructions and you will need to purchase a combiner box, fuses, grounding and other wiring, etc. I also added a battery monitor.