Do I Need Batteries For My Solar Power System?

People install solar panels for their homes for a variety of reasons. These reasons dictate the kind of solar power system you will get. You may want to simply decrease your electric bills. Or you may want to be completely off the grid. In this post, we’ll discuss about the general characteristics of batteries and then you can decide whether or not you need to install batteries for your solar power system.

What are solar batteries?

In our post about solar power systems, we mentioned that batteries are an integral part of either an off-grid or a hybrid system. Allow us to explain further. With any type of solar panel installation, the solar panels collect and produce electricity for you to use. Batteries collect your excess power when your solar panels produce too much during the day and you don’t end up using it. With grid-tied systems, the power grid serves as your storage so you don’t need batteries.

But with off-grid and hybrid systems, batteries do the job of storing your excess power. Off-grid systems require them because they replace the power grid. Batteries will provide continuous electrical power, possibly with the help of an additional generator. With hybrid systems, you can source your electrical power both from the grid and from the combination of solar panels and batteries. The advantage is, you will still have a power source even if the power grid goes out. It will also keep replenishing the power if the sun shines continuously too.

Types of solar batteries for residential use

Solar batteries are also called deep-cycle batteries. They’re designed to handle long and repeated instances of discharges and recharges as is typical in solar power systems. There are two typical deep-cycle batteries for residential use:

Lead acid solar batteries usually have a Depth-of-Discharge (DoD) of 50% to 60%. This means that you can only discharge power up to 50% and then you have to recharge it immediately. Going lower than 50% reduces the life span (5–10 years) of your battery.

Factors to Consider When Buying a Battery

There may only be two general types of batteries but there are other factors to consider when buying one. Here are some of them:

  • Power rating — A battery’s power rating is measured in kW because it tells you the maximum power it can provide at once. Say, you need many appliances to run from your battery, you need a higher power rating.
  • Usable storage capacity — refers to how long your battery can power your appliances or your home. If you need to send power to more appliances, your battery will run out of power fast. But if you only need to power a few small appliances, then your stored electricity will last longer.
  • Roundtrip efficiency — During the conversion process there are some losses in power incurred, from DC to AC (solar to electricity) and AC to DC (electricity to storage). Roundtrip efficiency is the number that tells you how much electricity you can take out of your battery, for every unit of electricity that you put in.


Lead-acid batteries are cheaper but they only last between 5–10 years. You also need a lot of space and regular maintenance for them. Lithium-ion batteries, on the other hand, may be more expensive but they last longer and use up minimal space.

You also need to take into consideration these factors: power and capacity ratings, the depth of discharge and the roundtrip efficiency.

Batteries fulfill the need for storage of excess power that can help you during a power outage or when you want to go off-grid. They can also decrease your power bill. If you think these reasons are enough and that you’re willing to put the money up, then, by all means, install batteries for your solar power system.

Send us a message on Facebook or visit our Ask Solar Mike website if you want to consult with a reputable solar power systems installer.

If you’re interested in accurately computing your solar panels requirement, schedule a call with us and you’ll be on your way towards your solar panel journey.

Originally published at on June 16, 2021.



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