Battery chemistry & storage
Enter the capacity you need and how often you'll cycle it. Compare five chemistries on the metric that matters most for daily use: cost per year.
How it works
Step 1
This comparison assumes frequent cycling. For occasional backup power instead, the best chemistry for backup only use comparison weighs the same chemistries very differently.
Step 2
Cost per year is sensitive to cycling frequency, so use your real usage pattern rather than a rough guess.
Step 3
The lowest cost-per-year option isn't automatically the right choice if it doesn't fit your space or budget upfront. The total cost of ownership comparison folds in more of these factors at once.
Daily cycling burns through a battery's cycle life quickly, which means the chemistry that looks cheapest per kWh upfront can end up being the most expensive once you account for how often you'll need to replace it. Cost per year of service normalizes for that, giving a fairer basis for comparison than sticker price alone, the same normalization the savings with battery vs without battery tool applies when it weighs a battery's ongoing cost against what it actually saves you.
LFP combines a long cycle life with high round trip efficiency and a moderate upfront cost, a balance that's difficult for other chemistries to match under frequent cycling. This is the core reason LFP has become the default choice for daily-cycling residential and commercial solar storage, a shift NREL's energy storage research has tracked as LFP has overtaken other lithium chemistries in stationary storage.
A flow battery's near-unlimited cycle life spreads its high upfront cost across many more years of daily use than any other chemistry, which can make it the cheapest option per year even at a modest residential scale like the example above. What actually keeps flow from being a common home pick isn't the cost-per-year math, it's the upfront price tag and floor space, both covered in the flow battery vs lithium comparison, and both factors NREL's battery storage cost data shows scaling very differently between residential and utility-scale deployments.
Once you've picked a chemistry for daily cycling, the LFP vs NMC cycle life comparison and round trip efficiency comparison can help refine the choice further with a closer look at each individual factor. Capacity fade is a maintenance question as much as a chemistry one. The panel degradation calculator in our Maintenance & Lifespan section can help you plan for it over the years.
Questions
LFP is the most common choice for daily-cycling solar systems, combining a long cycle life, high efficiency, and moderate cost into a strong cost-per-year figure, roughly $303 a year for a 10 kWh system cycled daily. Flow batteries can actually come out cheaper per year than that even at this modest scale, thanks to their near-unlimited cycle life, but the far higher upfront cost and much larger footprint are usually what rule them out for a system this size regardless.
Lead acid's short cycle life gets used up quickly under daily cycling, often needing replacement within a year or two, which drives its cost per year far above every other common chemistry despite its low upfront price. Daily cycling is specifically the use case lead acid handles worst.
It compounds daily rather than showing up as a one-time cost, so a chemistry with lower efficiency quietly wastes more energy every single cycle over the system's life. For daily-cycling systems specifically, that efficiency gap adds up faster than it would for occasional backup use.
NMC works for daily cycling but typically costs more per year of service than LFP, since its shorter cycle life doesn't offset its higher upfront price the way LFP's longer cycle life does. NMC tends to make more sense where its higher energy or power density outweighs the cost difference.
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