Substituting Li-Ion in place of the standard AGM battery will cost over $2000 extra per kW and we recommend a minimum of 3 kW. (However, expected battery life is four times greater.) Now brace yourself, you'll also want 2-8 more solar panels to make going lithium worthwhile (i.e. up to $4000 additional).
Li-Ion Weight Difference
An AGM battery weighs about 55 lbs per kW of storage capacity; Li-Ion batteries weigh about 25 lbs per kW. A 3kW SUNLION will weigh about 170 lbs and can be the linking power module of a solar electric power system or the primary unit of any offered inverter-model type.
The SUNLION unit looks similar to any other SUNRNR on the outside, but the inside (lithium ion in place of AGM battery) makes the input/output characteristics quite different:
Lithium Ion batteries can charge at a faster rate (50+%) than the 10% of battery capacity to which an AGM battery is limited. Each kW of Li-Ion can accept the charge of at least two 140W solar panels. That means a minimal 3kW SUNLION can fly over 800W of solar panels and as we always say, the power is in the panels.
However, an AGM battery is better than a Li-Ion at providing the hard start-up power for certain loads.
SUNRNR models are defined by their inverters (or lack thereof with respect to the non-invertered SUNPWR Power Module), not battery type. Any model can have either AGM or Li-Ion battery storage. It is possible to mix and match, e.g. having an AGM primary unit and a Li-Ion power module.
BUT ... various Li-Ion technologies are being researched and the dust hasn't settled. SUNRNR recommends postponing any SUNLION orders for now. Said another way: Jeff Chamberlain, who heads the lab's Collaborative Center for Energy Storage Research Science, told AVweb in an exclusive interview that overpromising on battery capacity is a result of snake-oil salesmanship and overenthusiastic entrepreneurs. But the fact is, lithium ion batteries remain a difficult and challenging chemistry to improve.