With two 15Ks... and therefore 6 MPPTs, how are you planning to divvy up your solar? 4 strings of 8, two on each 15K - leaving one MPPT on each unit unused? I'm curious of whay you chose (and more importantly WHY).
Being efficient is exactly why we are planning to build to Passive House specs. I'm planning to have propane at my property though - for a backup generator (I'm a network engineer, we like lots of redundancy in systems), on demand hot water and the cooktop (requirement from my wife... and if I'm being honest, I haven't met an electric cooktop that I like). Everything else will be electric. So according to PHIUS, we can get Passive House CORE certification, but cannot go for ZERO. The ZERO rating prohibits "fossil fuel combustion equipment". So I guess we'll just be CORE and net zero, without any "certification" (since certs aren't the goal, they're just a great way to ensure the design is implemented and confirming zero electricity bill is something I can easily do on my own). In fact, it's out plan to overbuild our solar array and be grid-tie, so we can put the extra back on the grid. In Oregon, net metering follows a 12-month calendar - and extra "credits" after 12 months gets dumped into a fund to help people that can't afford electricity... so it seems a nice, little way to give back for many many years. "Residential" is limited to 25kw for net metering, so my thought is to simply run 6 total strings of panels, similar in size to what you mentioned above... which would be ~ 21kw... and only pushing each MPPT ~ half of what is capable, which should also keep heat load inside both 15Ks even and low.