Is Solar With Battery Worth It?
With the cost of solar panels falling over 90% in the last decade, solar adoption has grown rapidly. However, without batteries, solar energy can only be used when the sun is shining. This intermittency issue has driven strong growth in the solar battery market, with global solar battery installations projected to grow at a 27% CAGR through 2025.
Pairing solar panels with batteries allows homeowners to store excess solar energy generated during the day for use at night. This gives homeowners access to solar power around the clock, reducing reliance on the grid. With the addition of batteries, solar systems can also provide backup power during grid outages.
For these reasons, battery attachment rates for new solar installations are rising quickly, especially in leading solar markets like California where over 30% of new solar installations now include batteries.
How Solar Battery Systems Work
A solar battery system consists of solar panels, a battery bank, a charge controller, inverter, and monitoring system. Solar panels capture sunlight and convert it into direct current (DC) electricity. This electricity flows into a charge controller, which regulates the voltage and current coming from the solar panels to safely charge the batteries. The batteries store the excess electricity generated by the solar panels for later use. When the home needs power, the inverter converts the DC electricity stored in the batteries into alternating current (AC) electricity that can power lights, appliances, and electronics in the home. A monitoring system allows homeowners to track how much energy is being generated, stored, and consumed (https://palmetto.com).
There are different types of batteries that can be used in a solar system, such as lithium-ion, lead-acid, nickel-cadmium, and flow batteries. Lithium-ion batteries are lightweight, have a long lifespan, and high efficiency. Lead-acid batteries are cheaper but heavier and have a shorter lifespan. The battery bank size and type is customized based on the home’s energy usage and storage needs.
Benefits of Adding a Battery
One of the key benefits of adding a battery to your solar system is having backup power during outages.1 When the grid goes down, your solar panels can continue sending power to your battery, allowing you to maintain electricity in your home. This prevents disruptions and provides energy resilience.
Batteries also enable you to maximize savings on your electric bills.2 Rather than sending excess solar energy back to the grid, you can store it in batteries for later use. This allows you to reduce energy pulled from the grid during peak rate periods in the evening. Solar paired with batteries gives you greater control over your energy usage and bills.
In some areas, utilities will pay you to export stored solar energy back to the grid during peak demand. Adding a battery provides the capacity to sell excess solar power back and earn extra income.3
Costs and ROI
The upfront cost of a solar battery system includes the cost of the solar panels, inverters, battery storage, and installation. According to the Solar Energy Industries Association, the average cost to install a solar system with energy storage is $16,836 before incentives.
There are federal and state tax credits available to help offset the costs. The federal solar tax credit covers 26% of installation costs for systems installed in 2022-2023, and 22% of costs in 2024 [1]. Many states and utilities also offer additional rebates and incentives.
It takes time to recoup the upfront investment from energy savings. The payback period refers to the amount of time it takes for the energy savings to equal the cost of the system. According to EnergySage, the average payback period for a solar battery system in the U.S. is 9-12 years [2]. Factors like electricity rates, solar resources, and incentives affect the payback period.
Ideal Setup for Solar Batteries
To maximize the benefits of adding a battery to your solar system, the ideal setup takes into account roof orientation, net metering policies, and time-of-use rates.
Having solar panels installed on a south-facing roof allows them to receive the most direct sunlight throughout the day (in the northern hemisphere). This ensures the solar array generates the maximum amount of electricity to charge the battery system and power the home (Evergreen Electrical, 2021).
In terms of policies, being in a region with net metering enables excess solar electricity to be exported to the grid in exchange for bill credits. Solar batteries can store this excess generation for later use instead of sending it to the grid for minimal credit. This increases savings compared to an export-only system (EnergySage, 2022).
Time-of-use electricity rates that charge more during peak hours also improve the economics. Solar batteries can be discharged in the evening to offset higher priced electricity from the grid (EnergySage, 2020).
Maintenance and Warranties
Solar panels and batteries typically require minimal maintenance to keep working at optimal efficiency. The main maintenance required is cleaning the solar panels as dust, dirt, bird droppings, rain, and other debris can accumulate on the glass surface over time, reducing the amount of sunlight that hits the solar cells. Professional solar panel cleaning costs between $150-$400 for a typical residential system, with an average of $300 (Source). This is recommended every 1-2 years.
Batteries may require additional maintenance like checking fluid levels and terminals. Battery manufacturers provide maintenance guidelines. Replacing batteries can be a significant expense down the road, with costs ranging from $5,000-$10,000 for a full home backup system.
Most residential solar panel systems come with a 20-25 year performance warranty, guaranteeing a certain power output. Manufacturers often warranty batteries for 5-10 years. Extending the battery warranty to 15-20 years is recommended to match the solar panel system lifespan.
Environmental Impact
Adding solar batteries can reduce reliance on fossil fuels for energy production, which has significant environmental benefits. According to a report, the average solar battery system can avoid over 2 tons of carbon emissions per year compared to using only grid electricity. By storing solar energy for use when the sun isn’t shining, batteries allow homes to get more of their electricity from clean, renewable sources instead of fossil fuel power plants.
However, proper battery disposal is crucial. Most home solar batteries today use lithium-ion technology. While lithium mining does have environmental impacts, recycling these batteries can recover much of the lithium for reuse. Some solar installers offer battery take-back programs to ensure batteries are disposed of responsibly instead of ending up in landfills. Overall, experts agree the environmental benefits of solar batteries outweigh the impacts as long as recycling protocols are followed.
Alternatives to Batteries
While batteries offer benefits for solar panel systems, there are some alternatives that allow using solar panels without batteries:
Generators
Generators can provide backup power when solar panels aren’t producing electricity. This avoids the high upfront cost of batteries. However, generators require fuel and maintenance.
Selling Excess Energy to the Grid
With net metering, any excess solar energy produced can be sold back to the electric grid. This provides a credit on your energy bill. However, without batteries you miss out on the opportunity to store and use that excess energy later.
Net Metering
Net metering allows any excess energy produced by solar panels to be sent back into the grid, spinning the home’s electricity meter backwards. This offsets electricity drawn from the grid at night or on cloudy days. Net metering policies vary by state and utility.
While these options avoid battery costs, they don’t provide the independence and resilience of having on-site battery storage. Overall, batteries maximize solar panel benefits but alternatives exist for going battery-free.
Case Studies
Real-world examples show the costs and benefits of adding batteries to solar systems. According to one case study from IRENA, a resort in the Maldives installed a 500 kW solar array with 570 kWh of lithium-ion battery storage. They avoided charging the batteries with diesel-generated electricity, thus using more of the solar resource instead of expensive diesel power. To AllCell’s knowledge, it is one of the largest battery storage systems in the Maldives, demonstrating the viability of solar plus storage even on small, remote islands (https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2015/IRENA_Battery_Storage_case_studies_2015.pdf?la=en&hash=9F36F343000EAC1763B685F18B9CD61311463A6E).
Another case study from Aeterna Energy described a homeowner in California who installed a 10.8 kW solar array with 2 Powerwall batteries. Their average monthly utility bill went from $400 to just $18 per month after installing the solar-plus-storage system. The homeowner estimates the system will have paid for itself in 5-6 years when accounting for tax credits and incentives (https://www.aeternaenergy.com/solar-with-battery-storage-case-studies).
These real-world examples demonstrate how adding battery storage to solar systems can provide substantial cost savings over time and maximize self-consumption of solar energy.
Conclusion
In conclusion, adding a battery to a solar panel system can provide homeowners with increased energy independence and savings on their electricity bills. By storing excess solar energy produced during the day for use at night, solar batteries allow homeowners to maximize their use of clean, renewable energy from the sun. While batteries do add significant upfront costs, for many homeowners the long-term savings and environmental benefits make them a smart investment.
For those considering solar batteries, the ideal setup depends on your energy usage, budget, and goals. Lithium-ion batteries provide the best performance and lifespan but are more expensive. Sizing your solar battery capacity to your typical evening load will allow you to reduce peak grid usage significantly. Ongoing maintenance costs are minimal, but be sure to understand the battery and installer warranties.
Overall, adding solar batteries allows homeowners to get the most out of their investment in solar panels. For those looking to maximize renewable energy usage, energy independence, and long-term savings, solar batteries are worth considering. Carefully evaluate your needs and budget to determine if batteries are right for your home.
