Can you Charge GEL Batteries with Solar? | How to Get them to Last!

Are you considering buying and using GEL batteries in your solar system?

GEL batteries are maintenance-free and can last for 10+ years.

Using GEL batteries as part of your off-grid solar system helps you tap into the advantages of using GEL batteries, right?

While you can charge a GEL battery with solar, you need to be aware of the sensitivities of GEL batteries in order to get the best performance from them.

So, in this article, I share some helpful information on how to charge your GEL battery using solar, including what components and settings to use, the dangers you need to be aware of, and how to get the most out of your solar system when using GEL batteries.

DIY Solar
DIY Solar

Can you Charge a GEL battery with a Solar panel?

Yes, you can reliably and consistently charge GEL batteries with solar without any harm to the batteries provided the solar system is well signed and the suitable voltage, current settings are used.

GEL batteries are being used and provide reliable power in many solar-powered standby and cycling applications.

Are GEL Batteries Good for Solar?

Yes, good quality GEL batteries have several advantages that make them attractive for solar applications in boats, RVs, and off-grid cabins as examples.

They are good for deep cycle applications, have a long service life especially when used in standby applications, and are maintenance-free too.

When sized properly, they can reliably power appliances that demand high starting currents like fridges, washing machines, or even air conditioners.

Compared to AGM batteries, they are more expensive though.

So if budget is an issue, you may want to consider good quality AGM batteries instead for your solar system.

GEL vs. AGM Batteries | Which is Better?

Consider GEL batteries if you need a reasonably priced battery with long life and good power supply capabilities.

Besides GEL batteries, there are other battery chemistries such as flooded lead-acid, AGM, and Lithium-ion phosphate batteries available each with its advantages and disadvantages.

Lithium-type batteries are light-weight compared to other battery types, are also maintenance-free, and can be discharged to 80-90% of their capacity consistently without damage.

They are more expensive compared to the other battery types.

AGM batteries are also maintenance-free, have good power handling capabilities but compared to both GEL and Lithium batteries do not have as long service life.

Check out: When to choose GEL, AGM, or Lithium-based batteries for your off-grid solar applications.

How to Charge a GEL Battery with a Solar Panel?

To charge a GEL battery safely so that it lasts, you need 3 basic solar components in your solar system – the solar panel, charge controller, and the GEL battery.

Solar Charge controller | Should you connect a solar panel directly to a GEL battery?

No – do not connect the solar panel directly to the GEL battery.

If you do so, you risk overcharging and damaging the battery.

Make sure the charge controller is set to charge the GEL battery type or you can manually select the manufacturer’s recommended battery voltage settings in the controller settings.

During cycle use and standby use, GEL batteries have precise voltages they should be charged to and charging currents that should not be exceeded, or else the battery is damaged.

Instead, the solar panel power should be connected to a charge controller which regulates the charging process to the specified battery voltages to prevent overcharging.

How to Size the solar panel to charge a GEL battery

The solar panel capacity (watts) should be sized so that there is enough energy stored and available for use by the appliances on a daily basis.

For an example, check out this article: What size a solar panel (watts) for a TV?

How to size a charge controller to regulate charging for a GEL battery

The charge controller should be able to handle the solar panel voltage and current to prevent damage.

You can check out this article on how to size charge controllers

Dangers faced when Charging GEL Batteries

When charging GEL batteries, there are common dangers that need to be aware of to prevent permanent damage to the battery.

These include charging with excessive voltages and currents (beyond the limits specified by the manufacturer), using the equalizing function of the charger, and combining batteries with different capacities (Ah).

Final Thoughts

You can charge GEL batteries with solar panels, in fact, there are many off-grid applications that use GEL batteries.

To charge them, make sure you use a charge controller to regulate the charging.

Also, ensure that the specified voltage and current limits for the GEL battery are not exceeded to prevent damage to the battery.

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