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by gkop 1464 days ago
Would you spell it out for us? What exactly happens when the grid fails at your site? Overnight, obviously you have no power. Then "the sun rises" but surely if there's any load, it must get above a certain point in the sky before it can run your house and charge your EVs, especially in the winter. And same thing in the afternoon, there must be a point where the sun is shining but too low in the sky and the load cannot be sustained- what exactly happens then?

(also, no clouds where you are?)
1 comments
toomuchtodo 1464 days ago
Assume there is no utility power. The sun must rise high enough on the horizon to energize the system (I haven’t done the math to know what the altitude/sky position is yet, I’ll report back). Once energized, the system will operate as a microgrid and attempt to maintain frequency and voltage if there are clouds until the sun sets and falls below the horizon. Some loads are more tolerant than others. The EVs of course will charge whenever there is power, and the hot water heater and pool pump will operate just fine only when power is present. Only the AC unit is fickle about power quality.

[removed strawman comment for being unnecessarily combative] When my utility is operational, I’m not just offsetting my consumption but also pushing back clean power into the grid for others locally to consume (which reduces the natural gas generation required of my utility) and while the failure mode isn’t perfect when the grid is down, it’s better than having no power at all (until battery storage costs decline).

Edit: https://pv-magazine-usa.com/2021/10/25/enphase-launches-micr...

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gkop 1464 days ago
Not a strawman (I don't think? not sure what you meant by this..), just very curious. You have a setup that is in between useless when grid is down, and fully self-sufficient. Seems possibly very practical to me, but I haven't heard of it before.
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bryanlarsen 1464 days ago
It is a very uncommon setup, I've met installers that don't know about it. The new generation of microinverters enable this setup more easily, so it should become more common.
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