Seasonal Solar Shutdown Guide

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• Introduction
• Before You Begin
• Complete Shutdown (Ideal for Covered RVs)
• Battery Storage: Lead-Acid vs. Lithium
• What If the Solar Panels Aren't Covered?
• Spring Startup
• A Few Extra Tips
• Conclusion

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Introduction

I know I've talked about this before, and I'm pretty sure I've even written an article on it. But recently I had a customer ask me to write down a simple step-by-step guide for shutting down their solar system for the winter. Then, about a week later, someone else asked me the exact same question:

"What's the proper way to shut my solar system down for the winter?"

When the same question comes up more than once, it's usually a good sign that it's worth covering again.

So, instead of answering it one person at a time, I thought I'd put together a straightforward guide you can refer back to whenever you're closing up your RV, seasonal cabin, remote property, or island getaway. Following a few simple steps can help protect your equipment, extend the life of your batteries, and make spring startup quick and hassle-free.

The biggest thing to remember is that not every battery should be stored the same way. Lead-acid and lithium batteries have very different storage requirements, and understanding those differences can add years to the life of your battery bank.

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Complete Shutdown (Ideal for Covered RVs)

If your RV is going to be stored under a cover, inside a shop, or anywhere the solar panels won't receive much sunlight, I recommend a complete shutdown.

Step 1 – Turn Off All Loads

Before shutting down your solar system, the first step is to remove all electrical loads from the system.

If you have an RV and it has been plugged into shore power to keep the batteries charged, make sure the shore power connection is unplugged first. You want the RV disconnected from outside power before beginning the shutdown process.

Next, turn off all the loads inside the RV. Turn off lights, appliances, electronics, and anything else that could be drawing power. If you have an inverter, make sure there is nothing plugged into it or running from it.

For a cabin or remote property, the process is the same. If you have been using a generator, make sure the generator is turned off and disconnected before shutting down your solar system.

The goal of this first step is simple: start the shutdown process with no electrical loads running. This makes the rest of the shutdown sequence safer and allows your equipment to power down properly.

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Step 2 – Shut Off the Solar

Once all electrical loads have been turned off, the next step is to shut down the solar charging system.

First, turn off the breaker or disconnect for the solar panels (PV array). This stops the incoming solar power from reaching the charge controllers.

Once the solar panels are disconnected, turn off the breaker for the solar charge controller (or controllers if you have more than one). If you have multiple charge controllers, shut them down one at a time.

By shutting down the solar panels first, you remove the incoming power source before turning off the charge controllers. This allows the equipment to shut down properly before moving on to the next step.

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Step 3 – Shut Off the Battery

Turn off the main battery disconnect or breaker.

At this point the entire system is safely shut down.

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Battery Storage: Lead-Acid vs. Lithium

This is where the two battery types become very different.

Lithium Batteries

Lithium batteries should not be stored fully charged for months at a time.

On your final day before storage, use some electricity. Run a few appliances, watch some TV, make coffee, or simply let the batteries discharge until they're around 50% state of charge.

That is the ideal storage level for lithium batteries.

Once they reach about 50%, shut the entire system down.

One of the great things about lithium batteries is their incredibly low self-discharge rate. Six months later they'll still be very close to the same state of charge you left them at.

Lead-Acid Batteries

Lead-acid batteries are the opposite.

I recommend charging them to 100% before storage.

Even with everything shut down, lead-acid batteries slowly lose charge over time. Starting at full charge gives them the best chance of making it through the winter without becoming excessively discharged.

If you have flooded lead-acid batteries, make sure the electrolyte levels are correct before putting them away.

Many cabins and some RVs are stored outside where the solar panels continue receiving sunlight.

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What If the Solar Panels Aren't Covered?

This changes things a little.

For Lead-Acid Batteries

I usually recommend leaving the solar system operating.

The loads remain turned off, but the solar keeps the batteries fully charged all winter. That's exactly what lead-acid batteries like.

When you come back in the spring, your batteries should be charged and ready to go.

For Lithium Batteries

Lithium is different.

If you're not using the RV or cabin for several months, I generally recommend storing the batteries around 50% and shutting the system down completely.

Keeping lithium batteries sitting at 100% all winter long isn't ideal for long-term battery life.

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Spring Startup

Getting everything running again is easy.

Simply reverse the shutdown process.

Step 1 – Turn On the Main Battery Disconnect

Restore power to the system and allow everything a minute to boot up.

If you have an inverter/charger or monitoring equipment, give it a moment to initialize before turning on loads.

Step 2 – Turn On the Solar

Once the main battery breaker is on and your inverter has fully powered up, it's time to bring the solar charging system back online.

First, turn on the breaker for the solar charge controller (or controllers if you have more than one). If you have multiple charge controllers, turn them on one at a time and give each one a few moments to initialize and confirm it's operating normally.

Once all of the charge controllers are up and running, turn on the breaker for the solar panels (PV array). The charge controllers will detect the incoming solar power and begin charging the batteries as soon as sunlight is available.

Bringing the system online in this order, battery first, charge controller second, and solar panels last, helps ensure the charge controllers start up properly and operate as intended.

Step 3 – Test Your Loads

Turn on a few lights, check your inverter, and verify everything is operating normally before using larger appliances.

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A Few Extra Tips

If you're using lead-acid batteries and it's a dark, cloudy spring day, don't hesitate to run your generator and fully recharge the batteries on your first day back. Bringing them back to 100% as soon as possible is always good practice.

If you have flooded batteries, check the electrolyte levels before putting them back into regular service and top them up with distilled water if needed.

If you have lithium batteries, there's very little maintenance required. Once you reconnect the system, they're generally ready to go.

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Conclusion

Seasonal shutdowns don't have to be complicated. A few minutes spent shutting your system down properly can help extend the life of your batteries and make spring startup quick and trouble-free.

The most important thing to remember is this:

• Lead-acid batteries like to be stored fully charged.
• Lithium batteries prefer to be stored at about 50% charge.
• If lead-acid batteries have solar available all winter, letting the panels maintain them is usually a great option.
• If lithium batteries won't be used for several months, storing them partially charged with the system shut down is generally the better choice.

Every system is a little different, but following these basic guidelines will give your batteries the best chance of providing years of reliable service.

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