How to Maintain an Off-Grid Solar System

As the name suggests, an off-grid solar system is one that is not connected to a utility grid. It is capable of producing electricity through photovoltaic panels that store energy in a battery bank.

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Tips for Maintaining an Off-Grid Solar System

The most important part of maintaining an off-grid solar system is taking good care of the battery bank. This can extend the life of your batteries and cut down the long-term cost of your RE system.

1. Check the charge level.


The depth of discharge (DOD) refers to how much a battery has been discharged. The state of charge (SOC) is exactly the opposite. If the DOD is 20% then the SOC is 80%.

Discharging the battery by more than 50% on a regular basis can shorten its lifespan so do not let it go beyond this level. Check the specific gravity and voltage of the battery to determine its SOC and DOD.

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You can use an amp-hour meter to do this. However, the most accurate way to measure the specific gravity of the fluid inside is through a hydrometer.

2. Equalize your batteries.


Inside a battery bank are multiple batteries with several cells each. After charging, the different cells may have varying specific gravity. Equalization is a way to keep all cells fully charged. Manufacturers often recommend that you equalize your batteries once every six months.
If you don’t want to constantly monitor your battery bank, you can program the charge controller to periodically perform equalization.

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The charger may allow you to select a specific voltage for the equalization process as well as the length of time to do it.

There is also a manual way to determine if your battery bank needs equalization. When measuring the specific gravity of all of the cells using a hydrometer, check if some are significantly lower than the others. Equalize your batteries if that is the case.

3. Check the fluid level.


Flooded lead-acid (FLA) batteries contain a mixture of sulfuric acid and water. As the battery charges or supplies power, some of the water evaporates. This is not a problem with sealed batteries but if you are using a non-sealed model, you need to top it up with distilled water.

Open your battery cap and check the fluid level. Pour distilled water until no metal lead surfaces are visible. Most batteries have to fill guide so the water doesn’t overflow and spill.

To prevent water from escaping too quickly, replace the existing cap of each cell with a hydrocap.

Before you remove the cap, make sure that the top of the battery is clean to prevent any dirt from getting into the cells.

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How often you top up will depend on battery usage. Heavy charging and heavy loads can result in more water loss. Check the fluid once a week for new batteries. From there you’ll get an idea of how often you need to add water.

Note: You don’t need to check the fluid level and the specific gravity in AGM and gel batteries.

4. Clean the batteries.


As water escapes through the cap, some may leave condensation on top of the battery. This fluid is electrically conductive and slightly acidic so it can create a small path between battery posts and pull more load than necessary.
To clean battery terminals, mix baking soda with distilled water and apply using a special brush. Rinse the terminals with water and make sure that all connections are tight. Coat the metal components with a commercial sealant or high-temperature grease. Be careful not to get any baking soda inside the cells.

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5. Do not mix batteries.


When changing batteries, always replace an entire batch. Mixing old batteries with new batteries can reduce performance as the new ones quickly degrade to the quality of the aged ones.

Properly maintaining your battery bank can improve efficiency and extend the lifespan of your off-grid solar system.

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