RV Daily "5 Solar Facts You Can't Ignore"

The article touched on my experiences so far with solar pretty well. My personal experience is real world camping solar harvest is considerably lower than one would expect based on what you read on the internet (Shocking isn't it) I'm lucky in that thanks to my job, I interface daily with a lot of folks, into tech, and into RVing. As a result, I've been able to borrow half a dozen very expensive controllers to slave into my solar system this year. So far, my preference for parked out in the open would be all my panels hooked in series, mppt controller. For the realities of the camping I do, the better choice for getting the max charge back into the batteries is all panels in parallel, a PWM controller that doesn't tend to get confused with wildly varying shading issues throughout the day. I also found my power usage is the highest when solar harvesting tends to be the worst due to shading, clouds, time of year etc. As a result, I'm going to expand my system 400 more watts, and always assume the generator will be needed from time to time.

The above said, in the interest of science, I'm going to volunteer myself to retire early next year, and get out in my 5er a lot more often in the interests of gathering more data, and provide the definitive data to put this issue to rest for good.

MrWizard wrote:
just because a person can buy some solar doesn't mean they can afford a lithium battery bank

Duly noted.

Yeah and they cost a lot more than the solar

So if you can afford a bank of lithium batteries you can afford solar

But the reverse is not true
just because a person can buy some solar doesn't mean they can afford a lithium battery bank

MrWizard wrote:
Once that battery starts charging the charge rate is going to drop off

Which is why Li batteries are so good with solar.

What a panel can produce into a loaded circuit aka grid tie or full load
Is one thing
What it can do while charging batteries which are a resistance load is different

I have over 600 watts of solar and 675 amp hour battery bank
I have never gotten 250 amp hrs in One day

Even on a perfect solar day with no generator use and a bank that never got full

I have gotten just over 2kwHrs in One day , 140+ amp hrs
And that was with twice your 300w for 125 amp hrs

That 125 amp hrs statement is very questionable

Granted if you have your 300w tilted into perfect sun on a cool clear day you can come closer than what my flat panels get, but not with a 100 amp hrs battery bank,
Once that battery starts charging the charge rate is going to drop off

#1 is poorly written. If they are saying you have a 100amp-hr battery bank, you should only use 50amp-hr max (less if you don't fully charge each day).

300w solar will produce around 125amp-hr on a typical day. Way more than needed. Even on a stray cloudy day, it should be keeping up.

It will certainly work but more efficient would be 150w solar which would keep up most days and if you get a couple cloudy days, you can do bulk charging for an hour or two in the morning.

Reality is you should do an energy audit and size the system accordingly.

wrong statements wrong
#1 too much battery...wrong
The correct answer 'Not enough solar for the amount of power used'
Cut down on power use

17v is the imp for most 100w panels , the peak voltage is 21>23v
Batteries don't charge at 12v , they charge at 13.6 > 14.4

300w of solar per 100 amp Hrs of batteries is ideal aka The off grid ranch house
It doesn't work that way for RVs
By that comparison I should have almost 2100w of solar on the roof
Or limit myself to 200 amp Hrs of batteries

BFL13 wrote:
Useful by being sceptical, but not totally accurate. Max amps is not at 17v eg. He is confusing Imp with Isc. See the IV curves for any panel.

Also, NOTC is not all that real either. I find you can get Isc amps from a properly aimed panel in a variety of conditions. NOTC does not always mean lower amps.

Also the remark about 300 watts per 100ah of battery, that is just stupid. So according to the article a 400 ah battery bank would need 1200 watts of solar.

Nothing new there, a little skewed maybe but close enough.

Useful by being sceptical, but not totally accurate. Max amps is not at 17v eg. He is confusing Imp with Isc. See the IV curves for any panel.

Also, NOTC is not all that real either. I find you can get Isc amps from a properly aimed panel in a variety of conditions. NOTC does not always mean lower amps.