Pre-Planning on a DIY "larger" solar system

[TomKady]

If you do a Sol-ark 12kW set up as grid-tied, the ATS function is built into it with a 4ms switching time, pretty much a UPS like performance. You can set the inverter mode as you need and your grid tie can provide what power demands are beyond the capacity. If you want it to prioritize serving load during daylight PV production hours, it can do that. Their documentation and support are very good IMO. Also, get someone qualified to draw up your electrical design with a complete list of components and details on bonding and grounding. More local, more better.
You can use the loads calculator on the Sol-Ark site to figure out how much you really need. The “12kW” is, I believe, meaning that you can serve continuous load of 9,000 W ac (16,000 surge) and 3,000 W dc battery charging if you have enough DC input from your panels. They can be paralleled to cover 18 kW continuous, but that’s $12K for inverter/charger/gen control/ATS functions built into those boxes - a decent value but absolute dollars rule.
Finally, look into how much additional you really get from seasonal adjustment = I’m at 41N, not 30 like you and its like 4.4% annualized - I don’t know if I’d bother creating mechanical complexity in my mounting for 2-3% - you have summer AC load - bias it for that and/or add more panels up to VDC input limits.
Hope it helps!

 

[TomKady]

I'm wondering about doing a manual, or programmed switch build where I run off solar/batteries during the day and then switch back to the grid, when power is cheaper, at night?

Hi, Boos, I’m wondering if you really have enough of a cost differential you pay for daytime vs. nighttime power? You didn’t mention where you are but here in NY, TOU (time of use) tariffs for residential are quite rare. Other places like CA, it’s common & high differential TOU prices.
It is certainly possible to design a “load shedding” off-grid solar PV system where functionally, you are grid-supplied but you have a manual transfer switch to island certain circuits and take them off grid, then supply them separately from your solar / batteries. I’d look for a good resource on this and get a real electrician to look at how to make sure those circuits are truly islanded when you flip the switch but the rest of your panel is still connected to the grid. You’d need a larger TS to take the whole house off, smaller if “load shedding” as I am suggesting, but that is mostly a matter of degree and solar + storage system size.