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RVing message boards => Tech Talk => Solar => Topic started by: tomnnva on January 21, 2012, 09:41:21 PM

Title: Solar Charger - Is it even worth it?
Post by: tomnnva on January 21, 2012, 09:41:21 PM
I was up on the roof of my Tour the other day and saw a solar panel I had entirely forgotten about.  Its a rather small solar panel and I wondered if it really does any good for my 8 rather large batteries or if this is Winnebago's way of claiming they are "green".  I could find no information in my 20lbs of manuals about this "system", but a light comes on during the day in the electrical panel that says "Solar Charging When Lit".  So is this system any good or should it be removed as a potential trip hazard?
Title: Re: Solar Charger - Is it even worth it?
Post by: donn on January 21, 2012, 09:57:30 PM
Probably one of those tiny 20 watt or so trickle chargers.  It is designed to maintain a fully charged battery during periods of storage with no hookups.  Basically worthless IMHO.  To handle 8 house batteries you would really need about 600 watts of solar panels.
Title: Re: Solar Charger - Is it even worth it?
Post by: afchap on January 21, 2012, 11:16:53 PM
I was thinking it is 10 watt ...and that is max if all conditions are perfect. In reality it is not even enough to overcome the parasitic drains on the battery bank while in storage ...it may help prolong battery life, but not enough to keep them in the black.
Title: Re: Solar Charger - Is it even worth it?
Post by: tomnnva on January 22, 2012, 07:56:38 AM
My thought also, it seems as if the "charger" generates just about amperage to illuminate the "Solar Charging When Lit" bulb in the electrical panel.
Title: Re: Solar Charger - Is it even worth it?
Post by: John Canfield on January 22, 2012, 07:58:24 AM
They typically are 10 watts unless Winnie started putting larger panels on the newer Tour/Ellipse.  Your 10 (or even 20) watt panel is superfluous - what Paul said above.
Title: Re: Solar Charger - Is it even worth it?
Post by: RCtime on January 22, 2012, 09:25:51 AM
I guess I will disagree.  Of course I only have three house batteries and two chassie batteries and live in sunny So. Calif.
My little 10W solar will keep my batteries maintained in storage IF  they are charged to begin with and the battery disconnect switch in on to eliminate parasitic draws.  I also use a TrikLstart.
In the winter time I do have to add an additional 10W portable I toss on the roof.
I love that little solar panel.
Title: Re: Solar Charger - Is it even worth it?
Post by: John Canfield on January 22, 2012, 09:33:17 AM
Sure - in that circumstance it might be useful. 

A ten watt panel is probably going to realistically put out maybe 500 ma in the best of conditions (full sun, southern latitude, summertime) and would probably be enough to overcome self-discharge of a couple maybe three batteries that are disconnected.  A lot of ifs, ands, and buts.
Title: Re: Solar Charger - Is it even worth it?
Post by: Gary RV_Wizard on January 22, 2012, 10:15:04 AM
I'm not sure about Winnies, but typically those little panels are wired to the chassis battery only and are intended only to offset parasitic draw, maintaining the charge in the chassis battery (assuming it is already fully charged) when stored for awhile (outdoors, that is).
Title: Re: Solar Charger - Is it even worth it?
Post by: RCtime on January 22, 2012, 11:31:40 AM
I'm not sure about Winnies, but typically those little panels are wired to the chassis battery only and are intended only to offset parasitic draw, maintaining the charge in the chassis battery (assuming it is already fully charged) when stored for awhile (outdoors, that is).

Gary
In our Winn ies they are wired to the house batteries.  In order to get any juice to the chassis batteries I had to add the TrickLstart.
Through the winter months and periods of rain/overcast like we are experiencing right now I usually have to go watch TV for awhile, running the generator about 2 times for the season and thats with the additional 10W solar on the roof.
But all in all they dont do much, but if you store your rig with no elect.available, you need to maintain your batteries, eliminate parasitic loads when stored, keep a watchfull eye on their condition and dont expect them to do the job of the larger panels.  It works for me, partly because I usually have an abundance of sunshine.
Title: Re: Solar Charger - Is it even worth it?
Post by: Duner on January 22, 2012, 08:15:05 PM
I removed the solar panel from my Winnie and put it on my enclosed trailer to keep my sandrail battery and the trailer battery charged while I stored it in Yuma, Az for 9 months while I fulltimed back east.    The first time I came back and the batteries were shot.  Dang I forgot to put a isolation diode in series, so at night the solar pane drained the charge.    The next two years,  I came back in Dec and the sandrail fired right up. 

I think I measured about 1.2 amps at 14 volts at high noon.  Anyway it did a fine job maintaining two "car" batteries long term.   On one hand I had it in Yuma, one of the sunniest places in USA.   On the other hand I had it in Yuma's 115 deg summers ..... heat kills batteries and solar panels put out less the hotter it is.   So I was a happy "duner" when buggy fired right up and I didn't have to buy a new battery or two.

My guess it that Winnie uses 15 watt panels.  When I'm not using the motorhome, it's parked under a carport awning so the solar panel never accomplished anything for me.  Now On my trailer I use it all the time and batteries stay at full charge.

Happy trails,
Bill

 
Title: Re: Solar Charger - Is it even worth it?
Post by: dirko on January 23, 2012, 12:08:43 AM
Hi Ho:   I have meant to move our 10 watt solar panel to the chassis battery which is not charged when connected to ac power.   It is currently connected to the house batteries and really doesn't accomplish anything useful because we leave the rig plugged in almost all the time.   If you had to store the rig where there is no ac available and didn't cover the solar panel with a roof I think it could be useful.  That is, if snow didn't cover the panel.
Title: Re: Solar Charger - Is it even worth it?
Post by: John Canfield on January 23, 2012, 07:45:33 AM
..I think I measured about 1.2 amps at 14 volts at high noon.  ..

Then you have a 16.8 watt panel  ;D.
Title: Re: Solar Charger - Is it even worth it?
Post by: Dougie Brown on February 19, 2012, 10:34:44 PM
I guess I will disagree.  Of course I only have three house batteries and two chassie batteries and live in sunny So. Calif.   My little 10W solar will keep my batteries maintained in storage IF  they are charged to begin with and the battery disconnect switch in on to eliminate parasitic draws.  I also use a TrikLstart.
In the winter time I do have to add an additional 10W portable I toss on the roof.
I love that little solar panel.

I'm facing the same situation when we store in AZ in May for around 6 months (no shortage of sunlight but of course very hot).  I have two house batteries and one chassis battery, a TrikLcharger (just installed) and a solar panel which appears not to be working.  I think this because the red indicator panel light has never illuminated, and when we returned after storing it for 2 months in Phoenix recently, the house batteries were dead.  It transpired though that one of the two house batteries was defective as it boiled the next week.

Questions:-

How can I tell what rating of solar panel I have?
If I determine it's not working by checking output with a meter, can I simply change it for another one by using the existing wiring?
Is it likely it's connected solely to the house batteries?

I'm hopeful that it will be enough to keep all the batteries alive during the 6-month storage.

As a footnote:- What's the consensus on the item at http://tinyurl.com/76uwkaj please?  Having spent some time tonight researching lots of input here on the forum, I can quite see why 100W is tons better than 10W for my purposes.  However, I also see that I will probably need a regulator if mine is indeed a 10W.  I am on the right track looking at this:  http://tinyurl.com/6vom9vy ?

Thanks.

Dougie.
Title: Re: Solar Charger - Is it even worth it?
Post by: Gary RV_Wizard on February 20, 2012, 07:38:17 AM
The factory installed mini-solar panel in our previous Rvs have always been wired to the engine battery rather than house. I think the theory was that if you could start the engine, you could get everything else going after awhile. But those little 10-15W panels were essentially worthless anyway.  This coach came with a full size 140w panel but I'm still not sure what battery bank it is wired to. It may be both, since it feeds through the battery control center box.

Yes, you need a regulator for any panel over 15-20 watts.

Another question to get answered: if the battery disconnect switch is off, is the solar charger still connected?
Title: Re: Solar Charger - Is it even worth it?
Post by: John Canfield on February 20, 2012, 08:33:21 AM
I'm always leery of some of the stuff sold on eBay, you pays your money and takes your chances.  I would prefer buying from somebody that has had a presence for a while and can provide service and support, even though it might be over the phone.

Can't speak to your model year Adventurer, but our little panel is wired to the house battery bank and it is not disconnected with the on/off switch.  You can look over your wiring diagram to how yours is wired.
Title: Re: Solar Charger - Is it even worth it?
Post by: Dougie Brown on February 20, 2012, 09:33:59 AM
All that figures, thanks.  So when I replace it with a beefier panel, can I re-use the existing wiring by connecting on the roof?  I'm guessing though that the new regulator complicates that theory.

Dougie.
Title: Re: Solar Charger - Is it even worth it?
Post by: John Canfield on February 20, 2012, 09:37:52 AM
My little 10 Watt solar panel has a 10 amp circuit breaker, so it and the wiring should easily handle a 50 watt panel, but you probably should rewire for 100+ watts.  Check your solar circuit breaker for amperage.

I thought about putting a 50 watt panel on the roof, but that's really not enough power to boondock with.
Title: Re: Solar Charger - Is it even worth it?
Post by: John Hilley on February 20, 2012, 10:00:30 AM
All that figures, thanks.  So when I replace it with a beefier panel, can I re-use the existing wiring by connecting on the roof?  I'm guessing though that the new regulator complicates that theory.

Dougie.

You should probably run new cable, at east 10 gauge, and just install the new pane in parallel with the existing panel.
Title: Re: Solar Charger - Is it even worth it?
Post by: Gary RV_Wizard on February 20, 2012, 02:52:00 PM
100 watts is not a lot of DC amps at the charge voltage of a solar panel, which is typically around 15v-16v in full sun (the only time you will ever see an actual 100 watts).  watts = volts  x amps, so we are talking 100w = 15 x  6.6 amps, so the wire doesn't have to be all that large. 14 gauge should be enough, eh? But that's likely more than whats there now...
Title: Re: Solar Charger - Is it even worth it?
Post by: John Canfield on February 20, 2012, 03:09:52 PM
100 watts is not a lot of DC amps at the charge voltage of a solar panel..

Right, and if I was storing a coach with no shore power available and didn't want to disconnect the batteries, I would want at least 150 watts of panels, depending on the latitude (further north, the lower the sun angle).  For boondocking, I would want as many panels that I could afford and that would fit on the roof  :D.
Title: Re: Solar Charger - Is it even worth it?
Post by: yolo on February 20, 2012, 03:45:13 PM
I guess that I got here late in the discussion.  Back to the OP question.

On my coach which has 4 6V golf cart batteries for the house and 2 31-size starting batteries for the chassis and a Trik-L-Start, the solar panel will keep them fully charged when the battery disconnect switch is off.  This is setting in full sun in Florida in the winter.   The batteries will measure 13.2 volts all the time.

My previous storage location was under roof and the panel would not produce enough to keep any battery charged.

Just my experience.
Title: Re: Solar Charger - Is it even worth it?
Post by: Dougie Brown on February 20, 2012, 04:33:02 PM
100 watts is not a lot of DC amps at the charge voltage of a solar panel, which is typically around 15v-16v in full sun (the only time you will ever see an actual 100 watts).  watts = volts  x amps, so we are talking 100w = 15 x  6.6 amps, so the wire doesn't have to be all that large. 14 gauge should be enough, eh? But that's likely more than whats there now...

Gary, having just come down off the roof & verified that the existing small panel is indeed dead, I would say it's at least 14 gauge in place.  Given it's going to sit through an Arizona summer, I still reckon 100W will keep it above the surface especially as I'll be disconnecting all the batteries again.  The supply disappears under the fridge vent and then immediately back downwards into the body of the coach.  John mentioned a breaker, but the panel in the cupboard above the cooker doesn't have one for the solar panel.  Having removed the breaker panel, we've checked all the wiring running from & to the roofspace (by pulling), and the solar panel supply definitely doesn't go there.  The red lamp (which has never illuminated) is on the opposite side on the Battery Voltage section of the Winne control panel.

Is the red indicator lamp likely to be part of a pre-installed regulator there?  If so, it seems to me I could just plug-in a new solar panel.  I am however quite happy to confess my ignorance publicly.

Dougie.
Title: Re: Solar Charger - Is it even worth it?
Post by: John Canfield on February 20, 2012, 04:45:21 PM
Dougie - time to get up close and personal with your wiring diagrams (http://www.winnebagoind.com/diagram/Wiring.htm).

There is no regulator for the little panels (nor do you need one) - it's just a couple of diodes and an LED.
Title: Re: Solar Charger - Is it even worth it?
Post by: carson on February 20, 2012, 05:02:27 PM
Just to keep things in perspective:  A solar panel needs SOL Sunlight to be able to be effective at all. No matter what the size.

  There are many areas in the US that have considerable cloud cover especially in the Winter. Good bye solar power.  The angle of the sun obviously changes every day, morning to night, month to month etc. and that has a great effect. Even here in Florida, the Sunshine State,we have recently had many days in a row without seeing the Sun.

Guess I am a spoilsport.   ::)

Carson FL


 Just because there is a panel on your roof does not mean your battery problems are over.

I think a read recently that someone had a solar panel under a garage roof and was hoping for a miracle.
Title: Re: Solar Charger - Is it even worth it?
Post by: Gary RV_Wizard on February 21, 2012, 11:18:26 AM
As John says, there is no regulator on those little panels, no breaker either and and probably not even a fuse. The Led comes on when enough current flows to light it ( maybe 100 milliamps?).   How does the solar charge current reach the battery(s)? It has to connect in somewhere, and you need to know where if you plan to disconnect the batteries when in storage.
Title: Re: Solar Charger - Is it even worth it?
Post by: Dougie Brown on February 21, 2012, 02:37:39 PM
That's the big question, Gary.  I've gone through the wiring location charts in detail, and the solar panel isn't even shown.

Dougie.
Title: Re: Solar Charger - Is it even worth it?
Post by: Tombstonejim on February 21, 2012, 02:46:03 PM
My HR came from the factory with a 65watt panel.     The panel feeds down to the battery compartment to a standard moringstar controller from there it feeds to the relay that seperates the house batteries from the starting batteries, it is wired to charge the house batteries only.
Title: Re: Solar Charger - Is it even worth it?
Post by: John Canfield on February 21, 2012, 03:30:27 PM
That's the big question, Gary.  I've gone through the wiring location charts in detail, and the solar panel isn't even shown.

Dougie.

Dougie - send Owner Relations an email (or@winnebagoind.com) and ask them.


My HR came from the factory with a 65watt panel.     The panel feeds down to the battery compartment to a standard moringstar controller from there it feeds to the relay that seperates the house batteries from the starting batteries, it is wired to charge the house batteries only.

65 watt panel - wow, you are lucky!  That is a useful size.
Title: Re: Solar Charger - Is it even worth it?
Post by: Dougie Brown on February 21, 2012, 03:44:08 PM
That's great John - top man.

Dougie.
Title: Re: Solar Charger - Is it even worth it?
Post by: jje1960 on February 21, 2012, 04:37:01 PM
I always had problems with keeping the battery from our 5.5k generator for our home charged.  It's in our shed, wired to a transfer switch underground inside the house garage.  Anyway, put a 10W panel outside the shed, wired to a cheap harbor freight charging regulator, years later, don't have anymore problem with the dead battery.  Also, for the heck of it, connected the genset battery to the lawn tractor in there... no more dead battery with that one either.  While a 10W panel will obviously not run appliances, sure seems like it's useful for keeping batteries topped off.  Just what I've found.
Title: Re: Solar Charger - Is it even worth it?
Post by: pokgunner on February 25, 2012, 05:57:04 PM
I've installed a much larger system that, with good sun, lets me dry camp for 5 days without running the generator.  The regulator I use can send 10% of the solar power to my chassis batteries.  The hardest part of the job was to figure out how  Winnebago ran the original wiring and how to access it to run my wireing.  Clearly who ever designed the wireing layout never expected to have to work on it.    I plan on connecting the small panel, that Winnebago installed, to a  fan to help the refrigerator.  But the refrigerator is in the slide out and I have not yet figured out how to get to the wireing that goes to the refrigerator.
Title: Re: Solar Charger - Is it even worth it?
Post by: DonTom on February 26, 2012, 12:18:02 AM
But those little 10-15W panels were essentially worthless anyway.
The 15 watt or less panels might be worthless--but I wouldn't knock the RV manufacturers for it. The wiring is NOT worthless and it can usually handle a lot more solar panels, making the job of adding more solar panels MUCH easier.

-Don- SSF, CA