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Lord of the Rant.
Formerly turtle2472
Join Date: Mar 2005
Location: Upstate South Carolina
2023-03-21, 15:56

I think I'm finally willing to share more details about my build. I struggle between sharing something I'm really excited about and maintaining my privacy. So rather than post the prints used for permitting about my solar build I built a basic diagram that will cover it.

I have a solar array that is rated for 23kW that feeds the two inverters. We are using SolarEdge with panel based optimizers. These help the strings maintain voltage in the event of partial shading and such. Those inverters feed the Tesla Gateway. This Gateway serves as the primary disconnect from the utility as well as the traffic cop for where I get and send electricity. Our build also uses two Powerwalls to provide power to critical loads in dark sky and grid down situations. During daylight we will continue living like there is no grid down. Since we only have two Powerwalls we are limited to ~60A continuous AC out. This would quickly fill if high current appliances all turned on at once. To prevent overcurrent you would normally use a dedicated critical loads panel to host those items you wanted backed up by the batteries. I want it all so I went a different route and am trusting relatively new technology.

Enter the Span Panel. It replaces the main load center/breaker panel in your home and allows for custom software based rules. So rather than have only the critical loads backed up, all my loads are. To prevent overcurrent the Span will shed loads when running on battery. This will mean all my high current loads will be shed immediately but programmatically. The breaker isn't turned off, but backend control of the breaker is. The Span Panel allows you to designate Must have circuits, Nice to have circuits and non-essential circuits. Non-essential circuits are shed immediately. Nice to have circuits shed at 50% battery capacity. Must haves shed when the batteries are dead. The downfall of the Span (beyond cost) is that is only has 32 breaker slots. We have to have a number of circuits in sub-panels. Those sub-panels are shed first with the true critical loads on individual circuits in the Panel.

I have been operating for almost two weeks now and have already gone positive for the month with net metering. So I'm sending more electricity to the grid than I'm using from them. We currently use the grid for overnights and dark days (cloudy, rain etc..). Net though, we are still positive. I have three apps to monitor everything though I typically only look at the Tesla and Span app since they provide everything I really need and have the controls for my system.

Here you can see the yellow line showing I'm powering my home electrical loads as well as charging the batteries AND feeding the grid.

So far I know I would like more energy storage for longer periods overnight as well as dark days. Other than that I really am genuinely thrilled with this system. It is a horrible shame it took us almost 18 months from start to finish. I'm actually in communications with upper management about the build and challenges we have faced along the way. The install process has been one wrong thing after another. So many challenges along the way. In the end I do believe it will be worked out.

Louis L'Amour, β€œTo make democracy work, we must be a notion of participants, not simply observers. One who does not vote has no right to complain.”
Visit our archived Minecraft world! | Maybe someday I'll proof read, until then deal with it.

Last edited by turtle : 2023-03-21 at 17:22.