Both lithium (LiFePO4) and gel/AGM batteries store solar energy, but they behave very differently over their lifetimes.

Depth of discharge

You can safely use about 80–90% of a lithium battery's capacity, but only around 50% of a gel battery's before you shorten its life. So a 100Ah lithium gives you nearly double the usable energy of a 100Ah gel.

Lifespan and cost-per-cycle

Quality lithium lasts 3,000–6,000 cycles; gel typically 500–1,200. Lithium costs more to buy, but spread across cycles it is usually cheaper per kWh delivered — and you replace it far less often.

When gel still makes sense

If your budget is tight today and your backup needs are light — a few lights, a TV, phone charging — a gel battery is a reasonable starting point. For daily cycling, fridges, or off-grid living, lithium almost always pays off.

Whichever you choose, buy genuine, warrantied cells. We stock both and can tell you the real cost-per-year for your usage.