Best way to shut down a small off grid system for non use

eastcaper · November 2013

I have a small off grid system in Los cabos Mexico. I bought the equipment form Wind and Sun,it is an Outback sysytem with 6 panels and 4 Trojan batteries. I am not there for much anymore and the system will be left for at least a year at a time. I was going to put tarps on the panels and disconnect the batteries while I was away. Is this a bad idea for battery life? Is it okay for the equipment? Is there a better way? Thank you

BB. · November 2013

Re: Best way to shut down a small off grid system for non use

If you have flooded cell batteries--They need, at least, 24 hours of charging every month.

If you leave a "typical" flooded cell battery setting for longer than 1 month between recharging, it will start sulfating. If you let your bank sit for 1 year between charging, it will probably be "dead" and unusable (especially in a warm/hot climate, batteries have higher self discharge the warmer they get).

Your best bet is to leave the array and charge controller connected and turn off/disconnect all DC loads (don't leave the AC inverter turned on idling, for example).

If your system is set up correctly, it should be OK. You might want to dial back the charging voltage to ~13.8 volts and no equalization (i.e., AGM settings) to reduce water usage by the battery bank.

Can you get a reliable person to come by and check the system (water levels, system voltage, possible a specific gravity check)? You want to make sure that the batteries do not "boil dry" while you are gone (with normal charging/cycling you should be adding distilled water--roughly--every two months to the cells). You also want to keep the batteries as cool as possible for longest life/lowest self discharge/etc... (don't want a south facing room with no ventilation getting the battery bank hot--77F or lower average bank temperature is better).

With the charging voltages dialed way back, the water usage should be way lower--But I don't have any idea if the batteries would last 1 year between waterings or not.

You can get away with a lot less solar panels (1% to 5% or battery bank capacity) when the system is not being used... Removing some panels and locking inside for security. But you don't need to do this otherwise.

Hopefully, somebody else with more experience than I can give you some tips/information too.

-Bill

Cariboocoot · November 2013

Re: Best way to shut down a small off grid system for non use

Welcome to the forum.

As Bill said taking the loads off and leaving the charging on is best, and the biggest problem will be water usage over a year. Without anyone to watch it there is a definite danger of water loss in that time span, especially in a hot climate like Mexico.

My advice would be pack up the batteries and take them with you so that they can get a once-a-month anti-sulphating charge and you will know the water level is correct. That way when you go back you will be bringing "known good" batteries with you instead of showing up to a dead system and having to turn around and go home.

Do not cover the panels in either case. They won't like the extra heat from being covered and they won't care if there are no loads on them. If you do take the batteries with you, disconnect the panels from the charge controller input.

jcheil · November 2013

Re: Best way to shut down a small off grid system for non use

When I hiked the Appalachian Trail this year, I was gone for 5 months and was concerned about the same thing.
Lucky for me I had a neighbor that would check it monthly.

However, how about an Automatic watering system???

I have heard of them but never used them.
Anyone have experience?

Best way to shut down a small off grid system for non use

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