Is $24,000 to install a Franklin aPower2 battery system a fair price?

I am a CA resident with PG&E. We just grandfathered out of NEM1 with our 7.5 kW ground array and Sunny Boy SB6000 inverter. I just learned about the aPowerS with a built-in inverter, and given our aging inverter, it seems like a better fit. I'm concerned about our aging inverter failing shortly after spending over $20k on a new battery system. We are considering waiting until next year to potentially get better quotes once the aPowerS becomes more available and to confirm our SGIP eligibility ($15k rebate). We signed a contract for the aPower2 but haven paid anything yet, and I'm wondering how binding it is, as nearly $30k seems ridiculous at this point. The 30% tax incentive comes after any SGIP rebates, but that's contingent on qualification, funding, and paperwork.