How Much Solar ? First Hand Report

[RJsfishin]

Just got set up here in Quartzsite, two 100 watt solar panels on my receiver hitch mounted polar mount, moving it 3 times during the day.
Panes were partly shaded by an old power pole till 9 am, then full sun all day. Solar display was blinking by 2pm, batts near full charge. We are a little conservative w/ led lites etc, but still burn sat tv at least 6 hrs a day.
This 200 watts (190 actually) it more than enuff for us, ......if we can depend on the sun even 50% of the time.
All this hype about voltage drop,......undersize wiring, etc etc, is a serious waste of time IMO,
......my voltmeters looked better when I got up this morning, than they have ever looked running my generator. I am thrilled w/ solar here in AZ. I wish I could be 1/2 this thrilled in Oregon ! :))

[BFL13]

IMO it is more likely SOC will be in the 90s when absorption starts, due to the low charging rate. Solar has low amps compared with the usual converter size amps, so where you might be at 80% with the converter, it would be much higher in SOC with solar on the same size battery bank.

[MNtundraRet]

Salvo wrote:
2pm seems a bit late to go into absorption. You're just 80% charged and there's only an hour of quality solar left.

Perhaps your wiring is inadequate? :B

Sal

I agree with you Sal about the 80% SOC when absorption charging started. 😉

Heavier gauge cable can certainly help when solar-power is at it's minimum at this time of year. Lots of variables come cold weather down there.

Then again the OP never stated how long he was camping down there. One week, month, 3 months? :h

The shorter the period the better chance RJ is right about not sweating the little things. Maybe he will let us know how long he plans to stay there. They way this winter is headed the longer the better. :B

I am certainly interested in hearing his further comments as time down there goes by. :C

[BFL13]

If skies are blue your solar can be way more than you need, then when it gets cloudy you can have not enough solar. It is luck of the draw what it will be like over the time you are camping that time. Next time it could be the other way around from last time.

All you can do is get some solar and whatever it does is what you get. If your RV can carry it and if you think it is "worth it" then the more solar you have to get by when it is cloudy the better. That will lead to many sunny days when you find you have too much solar and maybe wish you had spent some of that money on something else. You are never going to get it "just right."

Meanwhile, however much solar you take along, have a generator and charger handy so you are good to keep on camping no matter what the weather turns out like.

[RJsfishin]

For me, and IMO, its perdy simple. For 200 watts (190) I see 9 - 10 amps most times.
14 ga wire will easily carry 10 amps. But be cause of distance, we bump it up a notch,.....to 12 ga wire. Then just because of all the hype about a little voltage drop, we bump it up another notch,.....to 10 ga. Anything I'd gain from there, is not worth my caring about.

[Shadow_Catcher]

69Avion With a higher voltage panel voltage drop is less of a concern. I have a 185W 66 cell intended for a grid tie system that puts out better than 30V in shaded camp sites and from dawn to dusk.
For the rest a voltage drop calculator will tell you what you need and the ideal is to keep it below 2% drop and remember it is the results times 2. http://www.calculator.net/voltage-drop-calculator.html

[SCVJeff]

There's no such thing as too much solar if money isn't a factor.

[JiminDenver]

3 tons wrote:
From my own experiences (now at 440w), I'd say that considering higher latitudes, inclement weather (reduced harvest), and likely greater power demands, 200w is a good starting point and where I started from....Problem is, ya just can't have enough solar :)!!

3 tons

I agree. I have my second panel ready to go next season for a total of 450w. We don't really know what we will do with the extra power but I'm sure we will find some way to use it.

[RJsfishin]

Just for info, I bought a 100 ft roll of B&W 10ga twin lead when I started.
30ft from panels to controller, w/ a 20ft extension if ever needed. Then same wire from controller (4ft) to the 12v distribution center at the converter.
Ammeters and voltmeters all over the place 🙂 It don't matter what SOC the batteries are getting to, their better off than when I was generating them.
Like said, they'll get fully charged on the trip back home,....or on the PD when I get home someday 🙂

[BFL13]

smkettner wrote:
Another ~230w on the roof and even Oregon might be enjoyable :B
Thanks for the report. I agree solar does seem to put more charge in the battery compared to the generator.

On generator you do 50-90s which leaves the batts 10% undercharged and rapid capacity loss each succeeding 50-90 in a row. Solar lets you get to a higher SOC with more time and lower amps than you can afford with generator, so naturally you can do longer (weeks rather than days) off-grid before noting any capacity loss.

But you still are not truly getting to 100% every time, so there is no escape in the long run. It just takes longer, but that is good. Unless you are a full timer off grid, you do go home eventually and get a chance to put your batteries right after their ordeal. As long as you don't leave it too long to do a recovery desulfation.

Solar makes it much easier to do our seasonal off-grid thing now compared with the Big Losses episodes just on generator trying to do the same thing before. Just how much solar you need to get by is very situational with the individual camper.

[time2roll]

Another ~230w on the roof and even Oregon might be enjoyable :B
Thanks for the report. I agree solar does seem to put more charge in the battery compared to the generator.

[3_tons]

From my own experiences (now at 440w), I'd say that considering higher latitudes, inclement weather (reduced harvest), and likely greater power demands, 200w is a good starting point and where I started from....Problem is, ya just can't have enough solar :)!!

3 tons

[2oldman]

If your wires/connectors don't get warm, they're big enough. Your controller will get warm no matter what.

[Salvo]

With the right-sized cables, my 130W does fine too. Battery goes into absorption by noon to 1pm.

Sal

[JiminDenver]

Love our 230w 24v panel and MPPT controller, more than enough with morning sun and afternoon storms.

[69_Avion]

I recently installed one 250 watt, 24 volt panel with a MPPT controller and it seems like plenty for me.