What are my energy storage options?
Energy storage coupled with solar panels can offer many extra benefits that homeowners may be looking for. While they still come at a substantial cost, energy storage can be offset by certain incentives. For more info on what incentives are available, see our solar recipe guide.
Batteries can offer extra flexibility and independence from utility companies as well as additional savings if used smartly. Currently, there are numerous batteries to choose from but there are really only a standout few that are specifically manufactured with solar in mind. On this page, we will delve into why battery integrated solar might be right for you and what criteria to look at when choosing, as well as a comparison of the top choices.
The Pros & Cons of Battery Integrated Solar
Baked
- Save Money (Depending) – Avoid using electricity at peak times when it costs more with Time-of-Use plans. This is done by storing energy in a battery during the day, when it’s not being used, and using it in the evening when utility rates are the highest.
- Backup Power – With a solar system being required to be powered down during a blackout for safety reasons adding a battery will give you the ability to power your home during those times. Also, the sun will charge the battery for use each day. It’s usually still best practice to use for the essential appliances to make the energy last.
- NEM – Sends energy back to the grid if the battery fills up so you can still take advantage of net metering and get credits from your utility company.
- Monitoring – A lot of batteries can be monitored on the web or even on a smartphone app and be configured to the specific needs of a homeowner
- Incentives – California offers a limited discount of $0.35 per battery Wh (essentially 35% of the cost of the battery) through the SGIP. Then there is the federal tax credit which currently sits at 30% which shaves off more of the price (for more on SGIP and ITC see here). Basically, these two incentives can cover just over 50% of a battery when included together. See up to date SGIP availability at www.cpuc.ca.gov/sgip.
Half-Baked
- It’s Still Expensive – Battery technology has stayed generally the same for several decades and the price, which is going down but still considered expensive. This obviously depends a lot on your budget, situation, and intended use though. It’s not just the price of the battery, you would also have to consider the additional costs of labor, wiring, extra parts, inverter, etc.
- Space – Full-size batteries can potentially take up a lot of room (and are heavy)
- Battery Degradation – All batteries suffer from reduced capacity over time. Typically loses 30% capacity over 10 years.
What to Look For In a Battery
Manufacturer – There are several companies that manufacture batteries and more joining in each year. A proven track record for manufacturing can be an important criterion to use as well as what technology a manufacturer uses.
Price – It is always important to see what your budget allows and your own personal return on investment. With varying prices and sizes of batteries, it may be difficult to assess how they compare unless you break it down to the price per watt so that you can maximize your savings.
Capacity – Total amount of electricity a battery can store measured in kilowatt-hours (kWh). It should be noted that most batteries are stackable to increase storage and power.
- Higher capacity = energy independent, power the whole home, backup time for days
- Lower = emergency backup, power the essentials, backup time for hours
Power – How much at any given point a battery can output in kilowatts (kW). Typically batteries for solar have a peak power (highest power to “jump start” appliances) and a steady power (keep appliances running).
The Depth of Discharge – A percentage of the total amount of storage that a battery can actually output safely. Batteries need to maintain a minimum level of charge to keep them healthy and last longer only allowing a maximum amount of output usually between 85% to 95% of the nominal capacity (total capacity).
Round Trip Efficiency – A percentage of energy that is stored in a battery to the amount that can be used. Higher round-trip efficiency is better
Warranties – Most warranties are based on the expectation 1 cycle a day of draining and charging
- Years & Lifecycle– covers the battery for a certain number of years or cycles of useful life (usually whichever comes first)
- Percentage – guarantees at the end of the warranty that the battery will be over a certain percent of original capacity (usually around 70%)
Already Have Solar & Want to Add a Battery?
Adding a battery to your existing solar system can benefit a homeowner in many ways now that prices for battery systems have steadily come down. There are still some things to consider before adding battery storage.
Current Inverter – First you need to figure out whether or not if you have to update to a hybrid inverter to be able to store the excess energy in the battery (or purchase a separate inverter to work alongside original inverter). Also, some storage batteries already come with their own inverter built in eliminating the need to replace or buy one.
Solar System Size – If you are only producing a portion of your usage or are generally using most of the power generated by your panels then there will be little energy left to store in a battery. If this is the case you might want to look into expanding your solar system in addition to adding a battery. This will be more costly but over time can prove beneficial with raising utility rates.
If you want to know the feasibility and specific pricing involved with adding additional panels and a battery contact us for more information.
Reason You Are Looking
Save (more) money – you have to look at getting an affordable battery that can be just big enough to be used during utility peak usage times when the utility rates are high
Energy independent from the grid – look for the right size battery to cover the entire usage depending on how much your system can supply. Most batteries have the ability to stack to cover more usage.
Emergency backup power – smaller batteries can be used to stay charged to supply energy to the essential appliances
Solar Energy Storage Comparison & Calculator
We here at Solar Cake have gathered the numbers, stats, and prices for all the major batteries available to you. Get access to it below.