I finally got a quote for batteries. I called a few local electricians that didn't want the job, but referred me to an installer for Briggs and Stratton. Even though their battery offering is SimpliPhi, they were willing to quote me Pytes. I asked for V5, but they quoted E-Box, probably because that's what is available from their distributor. By example, Greentech has E-Box and not V5. With the E-Box, I'll need 5 batteries to achieve the full 12 KW capability of the 15K. I want a slim profile, so I had them quote the indoor box that holds 6 batteries and includes bus bars and cables.