If your goal is the longest life in daily use, lithium iron phosphate, usually called LiFePO4 or LFP, is typically the best choice. In real-world solar generator use, it usually beats standard lithium-ion and lead-acid by a wide margin because it handles many more charge and discharge cycles before noticeable capacity loss. A good LFP battery often reaches 2,000 to 5,000 cycles, and some higher-quality packs can do even better if they are not constantly run hot or pushed to extremes. For someone cycling a solar generator every day, that difference matters a lot.
Standard lithium-ion batteries, often NMC or similar chemistry, are lighter and can be very energy-dense, but they usually do not last as long in daily cycling. They are common in smaller portable power stations where weight matters more than maximum cycle life. In practice, they may offer around 500 to 1,500 cycles depending on the brand, how deeply they are discharged, and how well the battery is managed. They are not a bad option, but if you plan to use the system every day, they generally age faster than LFP.
Lead-acid batteries have been around forever and can be inexpensive up front, but they are usually the weakest choice for daily solar use. They dislike deep discharges, lose capacity faster when regularly cycled, and can be heavy and bulky for the amount of energy they store. In a backup setup that only runs occasionally, they can make sense. For daily use, though, they tend to wear out much sooner than the lithium options.
That said, chemistry is only part of the story. A well-built battery management system matters just as much. If the manufacturer limits overcharging, over-discharging, and excessive heat, the battery will usually last longer. Heat is especially important. A battery that is stored or used in a hot garage will age faster than the same battery kept in a cooler room. Depth of discharge also matters. If you regularly drain the battery to zero, lifespan usually drops. Keeping daily use in the middle range, such as avoiding full empty-and-full cycles all the time, can stretch battery life.
For most people buying a solar generator for daily use, LFP is the safest bet for longevity. It may cost more at the start, but it usually wins over time because it holds up better, keeps more of its capacity after years of use, and is less stressful to live with. If you want, I can also compare LFP vs lithium-ion vs lead-acid in terms of cost per cycle and which one makes the most sense for a specific watt-hour size.
