So, I'm the sound guy that decided he didn't want to travel his whole career and started branching off between shows. Ive been "freelancing" for a solar company here in FL. Of course I'm looking for reviews on the new L series and get sucked into a solar/battery discussion.
First, Congrats on a 4kWh (part of me thinks you meant to type 40kWh?) a day. National average is about 30KWh.
Assuming 40 kWh, you'd need an 8kWh array(about 28 panels). This is based on an industry standard "5 hour solar day". 8kW/hour x 5 hours = 40kW. Ready for the sticker Shock... about $40k.... but wait theres more. Government tax credit knocks 30% off that. So now your looking at $28k. Financed at 2.99% over 144 months is $229.60 per month.
So, I'd argue, IF your bill is more than $229.60, not $400, you're already at a net neutral.
Net Metering is your most cost effective solution to not paying an electrical bill. What I would like to see is 3 or 4 of these tesla batteries "topped off" by my array so that when the power DOES go out I have a reliable backup. Thus conserving the amount of times your wall battery cycles and prolonging the life of your battery.