Off-grid battery system fall maintenance checklist

Battery systems at seasonal properties require a different level of care heading into the fall and winter months. On this edition of The Pitch, Jeff Myles, marketing manager of Rolls Battery, walks us through a fall maintenance checklist for solar installers. Check out the full 13 minute interview and/or skim the highlights below.

Why is having a fall maintenance routine important for seasonal properties?

Myles: “Taking the time to properly prepare the system for winter storage will give the homeowner several more years of use.

“Like our bodies, deep cycle batteries work best when they’re exercised.  They perform best when they’re fully charged often. Allowing the battery bank to discharge heavily will increase the likelihood they’ll need to be replaced sooner.

“If the batteries are discharged in cold weather, they also run the risk of freezing. At 50% SOC they can freeze at -20C (-4F). Batteries self-discharge when not in use so packing up and leaving without preparing for winter storage will often result in problems. Batteries self-discharge faster in warm temperatures and this slows down as ambient temperatures drop so it’s best to keep them topped up with a charge and well above 50% SOC as much as possible.

“Off-grid systems with dead battery banks often won’t charge properly or the system won’t attempt to charge the bank at all. If the battery bank is fully discharged, damaged or has failed batteries which reduce the voltage below the low-voltage cut-off range, the system will not charge.  This is not only an inconvenience when you want to start things back up again, but may require battery replacement or another charge source (generator) to boost the discharged bank back to an acceptable voltage before charging with the PV array.”

Do different locations require different checklists, in terms of either remoteness or climate (or site usage)?

Myles: “Climate is definitely an important factor.  Much like usage, each property is also unique and will have different maintenance requirements based on access to the property as well as ambient temperatures.

“Unfortunately, freezing batteries will not only result in electrolyte spills but also require costly replacement.  Making sure the batteries are fully charged before disconnecting the system for winter if you’re not able to top them up with a refresher charge every few months.

“Some may have PV panels fixed to a roof. Others may have a ground or roof-mount systems that can be adjusted (tilted), which makes a difference. If snow and ice buildup on PV panels is likely, you have two options. 1) monitor and remove as necessary… or 2) if it’s in a remote location without no access, either tilt the PV panels to prevent buildup or fully charge the battery bank, disconnect from the system and shut everything off.”

“If the property is in a remote location that’s inaccessible for several months and will sit in freezing temperatures the installer or homeowner will need to prepare for extended storage.”

After doing that initial assessment of the site location and usage, walk us through the general preventive maintenance routine. What are we checking, what are we adjusting, and why are we doing it?

Myles: “If the batteries are flooded, specific gravity of each cell in the battery bank should be tested routinely to make sure they’re all operating as intended and the charge is balanced. If not, a corrective equalization should be done (controlled overcharge) to remove any sulfation build-up that occurred during the summer months. Sulfation hardens on the plates when left for extended periods, so removing it before storage will avoid capacity loss.

“Flooded batteries also require distilled water and may need a top-up after several months of warmer weather and charging/discharging.

“Battery terminals heat up and cool each time the bank is charged. Over time, this can cause terminal connections to loosen. The terminals should be inspected for corrosion buildup, disconnected, cleaned, and reconnected again each fall, following the manufacturer’s recommended torque setting. 

“If the system will be shut off, it’s a good idea to disconnect the cable connection to the battery bank to prevent accidental discharge. Most system components will continue to draw a small amount of power, even in standby, which will speed up battery discharge.”

The Pitch is a side project of Solar Builder magazine. We chat awkwardly with manufacturers and suppliers about their ideas and innovations so you don’t have to.

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