Safe to leave solar hooked to batteries unattended?

[OregonTRX4]

I leave my trailer in a rural area where we camp with no hook ups. I have been looking into solar. A friend leaves his batteries hooked up to his solar and the batteries disconnected from the trailer so that they are charged when we come back to the property every 1 to two weeks. Is there any risk to this? Any known mishaps in regards to fire or something I am overlooking? It would be terrible to have something go wrong while I am not around and have it burn the property down.

Thanks.

[MEXICOWANDERER]

Fuse solar AT THE BATTERY. Reason?

From the battery to the controller the wiring is vulnerable to full battery wattage. If there is a fault between the battery and the controller the battery fuse (a foot and a half distant to protect against corrosion) will protect the 2 controller wires.

These days controllers have fuses, right? Or did they disappear along with common sense? The fuse in the controller should protect the controller and wiring to the panels.

On a PROPER SYSTEM is is not sorta impossible to damage a solar panel which is enduring a full short circuit condition for oh say, five years?

But by arcing I can melt terminals on a high wattage system. Not with 150 watts, rather a thousand or two. Exactly the same thing as a circuit breaker fire. Following manufacturers instructions, and regular maintenance and inspections will eliminate this possibility.

[mena661]

BFL13 wrote:

Here is the ref--wade down to the strings fusing part

http://www1.cooperbussmann.com/pdf/9df1f7ec-8c62-4210-8cf8-9504927394f0.pdf

Panel specs have a fuse size mentioned for that application "series fuse rating" eg my Sharp 130w says 15a and so does my Hanwha 230w panel have 15a for that.

( I am not sure all PWM controllers short the panels--the "shunt" type
do, but not sure about the "series" type.) You can short the panel no harm done.

Thanks BFL. After reading that document, it does make sense with parallel strings to have fuses after a certain amount of strings to protect the wiring and panels themselves.

[NinerBikes]

OregonTRX4 wrote:
I am on a budget and was wondering how this kit looked for the purpose discussed?
http://www.amazon.com/dp/B00BFCNFRM/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=EWWQQYUK3TWE&coliid=I2Y8GFT7NY2D0N

120 watt solar panel kit

More watts, for almost the same price, and portable. Better value, in my eyes.

[rreynold51]

My only concern with leaving solar on is ensuring the battery water levels don't drop....we store away from the house so would have to check on it periodically....but we have multiple fuses in the line to protect things and a smart controller...it does well when we are in the rig....so no reason it wouldn't do well when we aren't there I guess.....

[time2roll]

http://www.amazon.com/dp/B00BFCNFRM/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=EWWQQYUK3TWE&colii...

[OregonTRX4]

I am on a budget and was wondering how this kit looked for the purpose discussed?
http://www.amazon.com/dp/B00BFCNFRM/ref=wl_it_dp_o_pC_nS_ttl?_encoding=UTF8&colid=EWWQQYUK3TWE&coliid=I2Y8GFT7NY2D0N

[BFL13]

mena661 wrote:

2oldman wrote:

RoyB wrote:
all solar panel cables should be protected by high current fuses so that short circuits will blow the fuse

Would this happen by two wires crossing, or some other way?

I'm not sure why you need a fuse on a device that's designed to be short circuited. Yes, panels are designed to be short circuited, that's how PWM controllers work they short circuit the panels. That's where you get your Voc and Isc ratings from. Panel wiring is typically #12 which is rated for 45 amps. Now worries there either. I can see putting a fuse on the controller output but not on the input.

We had a thread about this some time ago. ISTR there was a reference to possibly using a fuse with each string of panels in series up to three not needed but with four or more you need a fuse? Can't remember. Look it up if important.

Here is the ref--wade down to the strings fusing part

http://www1.cooperbussmann.com/pdf/9df1f7ec-8c62-4210-8cf8-9504927394f0.pdf

Panel specs have a fuse size mentioned for that application "series fuse rating" eg my Sharp 130w says 15a and so does my Hanwha 230w panel have 15a for that.

( I am not sure all PWM controllers short the panels--the "shunt" type
do, but not sure about the "series" type.) You can short the panel no harm done.

[time2roll]

Mine are always on. Trailer stays on also. Check the battery water level every six months or so.

The real issue will be if the battery runs completely out of water and there is an internal spark. Shorted cell may cause high water usage. But these things can happen in normal use. Solar seems to reduce the issue and extend the life of the battery.

[SCVJeff]

Currently at 500w on the roof. I started the panel farm specifically because of storage issues draining the batteries. The batteries are always on the solar.

[wa8yxm]

If you have a proper solar charge controller this is a very good way to do it, provided you hook up as follows

Solar panels==Controller===Batteries==Disconnect---RV

If you do not have a controller, it will not work.

[mena661]

2oldman wrote:

RoyB wrote:
all solar panel cables should be protected by high current fuses so that short circuits will blow the fuse

Would this happen by two wires crossing, or some other way?

I'm not sure why you need a fuse on a device that's designed to be short circuited. Yes, panels are designed to be short circuited, that's how PWM controllers work they short circuit the panels. That's where you get your Voc and Isc ratings from. Panel wiring is typically #12 which is rated for 45 amps. Now worries there either. I can see putting a fuse on the controller output but not on the input.

[handye9]

I disconnect my solar panel, only when removing the batteries for winter storage. Spring, summer, and fall, they stay connected. About once per year, the batteries need a little top off on the water.

[2oldman]

The only real danger I can see is overcharging. If you have a decent quality functioning controller, that will not happen. Be sure the battery water is up to level before leaving.

RoyB wrote:
all solar panel cables should be protected by high current fuses so that short circuits will blow the fuse

Would this happen by two wires crossing, or some other way?

[red31]

My panel/controller is a maintainer most of the time.

[wolfe10]

Leave it connected, BUT be sure to have a quality CONTROLLER between panel(s) and battery(s).