As home solar technology has rapidly evolved, so has the variety of solar offerings. While different solar panels or solar storage batteries may look the same, the inner-workings of the technology may be very different.
When it comes to home solar storage batteries, the most often considered choices are lead-acid or lithium-ion. You may have seen lead-acid batteries as part of a solar emergency kit. Right now, Sunnova offers lithium-ion batteries like Generac PWRcell™ and Tesla Powerwall.
If you’re considering a solar storage battery, we’ve outlined some specifics to help you weigh the pros and cons of each type of battery.
Lithium-Ion vs. Lead-Acid – An Intro
Lead-acid batteries are commonly used in smaller applications - for example, golf carts, wheelchairs, and scooters. Lead-acid batteries are cost-effective for short bursts of backup power and infrequent use as they generally have a short lifespan and may need frequent replacement.
Lithium-Ion batteries are generally considered to be the most efficient option for home solar storage - they are more compact and have a greater depth of discharge than lead-acid batteries. Lithium-ion batteries can be used every day with very little maintenance and generally have a long lifespan.
Which Battery is Best for Your Home Solar Backup?
A few factors to consider:
- Cycle life - how often a battery is charged and depleted.
- Capacity – how much energy can be stored and discharged by the battery.
- Depth of discharge - the percentage of a battery that can be safely depleted without damaging the battery.
- Cost – total cost of the battery.
- Warranty – is your battery covered by a warranty?
The more you cycle a battery, the less effective the battery becomes. All batteries are made to handle a set number of cycles.
Lithium-ion batteries typically last for several times the number of cycles as lead-acid batteries. Specifically, for everyday use with home solar, lead-acid batteries often last under two years, while lithium-ion batteries can last 10 years, depending on usage and other factors.
While energy storage capacity will vary by individual battery, lithium-ion batteries are proven to have significantly higher energy density than lead-acid. This means that lithium-ion batteries can store more energy in the same physical space than lead-acid batteries.
For emergency solar backup power, it will take several heavy lead-acid batteries to match the capacity of one large lithium-ion battery.
If you’re using a solar storage battery, the battery will never deplete 100%. If you deplete a battery more than the recommended depth of discharge, you may risk damaging the battery.
Lithium-ion batteries can be depleted to around 80% capacity or more, while lead-acid batteries can usually be depleted to 50% capacity. Basically, lithium-ion batteries have more usable battery capacity.
While lead-acid batteries may be cheaper at initial purchase, their shorter cycle life means that you will likely have to purchase batteries more often.
When purchasing a battery, it’s important to check the warranty coverage offered. If you add a lithium-ion battery from Sunnova to your existing solar system, the battery comes with a 10-year limited manufacturer warranty.1 For parts covered under this warranty, Sunnova will coordinate all maintenance and repairs to ensure your experience is hassle-free.
Did You Know?
The International Space Station is making the switch to lithium-ion batteries! Since 2017, NASA has replaced nickel-hydrogen batteries with lithium-ion batteries to store excess solar produced by the ISS’ solar array. Learn more.
Add Battery Storage
At Sunnova, we are focused on delivering affordable, renewable, and resilient energy solutions for our customers. Through the use of solar + battery storage, we offer energy backup to ensure that, our customers can live life uninterrupted.2
If you're new to solar, learn more about our Sunnova SunSafe™ home solar + battery storage combination. If you already have solar, we can add a solar storage battery to your existing home solar system.
Questions about battery storage? Get in touch with one of our solar experts!
1: The system warranty is based on the manufacturers’ warranty. Refer to the Warranty Agreement for complete warranty terms and limitations.
2: The amount of power available during a power outage is limited, depending on the loads connected and the customer usage during a power outage. Some solar systems and/or its components (including batteries) could require repairs to be completed after certain events. Please refer to your agreement for conditions and limitations.