Solar panels with no load … OK?

[featherliteCT1]

I have been taking my batteries out of my truck bed and storing them in an air conditioned garage with the solar panels disconnected from my charge controller.
Consequently, my Renogy, monocrystalline solar panels mounted on the roof of my camper shell set out in the sun for extended periods of time with no load applied to the panels.

Does leaving the solar panels out in the sun for extended periods of time with no load harm the panels or shorten their useful life?

[edgeau]

I just hooked up one that had no use in a year and it seems fine

Sent from my Pixel 3 using Tapatalk

[KTM_Guy]

You should be fine if just the panel(s) are left exposed to the sun with no load. The problem can be if the charge controller is connected to the panel(s) with no battery.

Todd

[John61CT]

Usually the opposite.

Always connect SC to battery bank before connecting panels.

Always disconnect panels from SC before disconnecting from battery.

Some SCs are fine though.

Panels left open circuit, even short circuit no problem - for the panels.

[RJ Howell]

I'm one of those better safe than sorry types, so I always cover mine.
I also took some time and researched this question a bit. Seems no harm to the panel left in the sun with no load (short of just heat). What I learned, is the panel needs a load to produce current. I know you can read voltage with no load, so always assumed there was some current involved. I'll stay with my habit of covering them when not in use.

[Aguyfromohio]

... I know you can read voltage with no load, so always assumed there was some current involved...

Yes there is indeed some current involved, but not much.
The sort of voltage meter most of us own has such a huge internal resistance that the current running through them is almost zero.
A typical value might be ten million ohms. The classic version of Ohms law say E = IR, or voltage = current times resistance.
Solving for current says I = E/R. Lets assume a 120 volt dc source measured by a meter with ten million ohms internal resistance. In this case current is:

I = E/R
= (120) volts / (10,000,000) ohms
I = 0.000012 amps

That's twelve one-millionths of an amp, or twelve micro amps. It's not zero current, but it's so close it might as well be zero for all practical purposes.
It's perfectly fair to say we've measured voltage without applying a load.

[H.A.]

Electrically it makes no difference. Covering them while disused is not real important, but not a fools errand either.
Keeping anything whats unused out of the sun & elements helps with longer lifespan.

[featherliteCT1]

Usually the opposite.

Always connect SC to battery bank before connecting panels.

Always disconnect panels from SC before disconnecting from battery.

Some SCs are fine though.

Panels left open circuit, even short circuit no problem - for the panels.

The above procedure agrees to what the manual says for my Trimetric Solar Charger.

[featherliteCT1]

Thanks for all the responses to my original question. I had previously done a bit of research before asking my question but never found any information that seemed credible, one way or the other.

I think the answer is that leaving the panels disconnected from the solar charger has no adverse effect on the life of the panels. However, I agree with H.A.'s comment that, in general, it is best to keep anything out of the sun if possible. However, in my case, I do not want to remove the panels from the top of my truck and my truck sets out in the sun all day while I am at work .

Again, thanks for your input.

[tony.latham]

I have been taking my batteries out of my truck bed and storing them in an air conditioned garage...

Which begs the question of why you would pull them if they are maintained by the PVs? Just curious.

Tony

[RJ Howell]

I have been taking my batteries out of my truck bed and storing them in an air conditioned garage...

Which begs the question of why you would pull them if they are maintained by the PVs? Just curious.

Tony

Also curious! My question added would be: What type battery do you have?

[featherliteCT1]

“Which begs the question of why you would pull them if they are maintained by the PVs? Just curious.”

Good question, and thanks for asking.

“What type battery do you have?”


I pull my two Deka, 6v, 235 amp hour batteries out of the camper shell and put them in the garage to get them out of the heat.

When my truck is in the sun, with the two slider windows open about 8 inches, and when the outside ambient temperatures are 80F and 90F, the temperatures inside of my camper shell are 94F and 124F, respectively. As you can see, the inside temperature rise is not linear.

About two weeks ago, I installed a fan running off an old Walmart deep cycle battery I put in the camper shell, and the numbers changed from 80F and 90F, to 94F and 104F, respectively. At least the fan somewhat reduced the inside temperature rise. But it is a pain in the butt to remember to close the windows if rain is in the forecast.

In the summer time, I do not put my truck in the garage because then the truck heats up the house. I do not have air conditioning in my house.

I am still concerned about leaving my solar chargers in the camper shell in the heat.

The specifications for my Trimetric SC 2030 charger say ambient temperature range of 0F to 140F. I have not tested the temperature of the charger when it is under load.

The specifications for my CTEK 250S Dual charger (DC to DC and solar) say ambient temperature range minus 4F to 122F.

During the summer, I think I will pull the CTEK and leave the Trimetric in the camper shell.

[tony.latham]

the temperatures inside of my camper shell are 94F and 124F

Holy-molly!

T

[John61CT]

How could a truck add heat to the house sitting inside a garage?

[featherliteCT1]

How could a truck add heat to the house sitting inside a garage?

After the truck sets out all day in the hot sun in the asphalt parking lot at work, and after driving the truck from work to home, the engine and the entire mass of the truck gain significant heat. Thereafter, when the truck is then parked in the garage and shut off, the truck acts like a big heat sink. The garage is insulated and attached to the house (there is a 2x4 studded wall separating the garage from the interior of the house), the heat from the now heated garage passes through the wall into the living quarters of the house.