Solar PV disconnected in the sun

[force9BOAT]

Hello,

Is there risk of damage to solar panels if they are left (for several days or a few weeks) in full sun while not connected to batteries or other loads?

I'm thinking that if I left my home for a couple weeks vacation I might want to shut down my RE system while I'm gone rather than leave it unattended.

Thank you,

Rob

[DanB]

No - it wont hurt them.  Though your batteries will self discharge about 5% per week so for the sake of the batteries you may not want to unhook it.  If you have a good charge controller then there should be no harm in leaving things wired up.

[Nando]

No, they do not get damaged at all, they may last longer because no current drawn.

One thing you could do is to add a lamp to reduce the current to float level

Measure the battery voltage disconnected from charging and loads.= Vbat

Measure the solar panel at full sun.= Vsolar

then Vsolar - Vbat = Vresistor

For each battery amp-hour capacity give 5 milliamps current.

So if you have a 50 amp-hour battery : 50 * 5 milliamps = 250 milliamps.

So Vresistor/0.25 = Resistor value that you place in series between the solar panel and the battery

Resistor power = Vresistor * 0.25 * 4 = Resistor wattage .

This way your battery will be fully charged when you return and the small charge you have will, as well, do a deep desulfation cleaning.

This procedure should be limited to about 3 weeks -- if you can measure the current you will read around 200 to 220 milliamps ( depends on the solar panel manufacturing process and the capability to supply low currents above the Vmp levels)

Nando

[ghurd]

Get a good controller. That's what they are for.

Check the battery water before you leave, and the minute you get back.

G-

[mjchee]

 As long as you have a good charge controller, you should be alright. If  you are going to be gone for 1 year or greater, then do shut it down! Remember to cover up your panels with a protective covering of some sort. But remember you will be hurting  your batteries, due to not having them recieving any charge for that certain amount of time. It depends on how long you are going to be gone. Just consider some common sense and you'll be alright.