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This is something I've been thinking about recently due to a potential new policy from PG&E (Northern California electric utility) in which they would preemptiv
by sxates 8y ago
This is something I've been thinking about recently due to a potential new policy from PG&E (Northern California electric utility) in which they would preemptively shut down electricity to high fire risk areas when red flag conditions are present. I live in the Oakland hills which would be affected by that plan. PG&E says they expect such an outage would occur 2-3 times per year in October/November, and that because they have to do a lot of safety checks before restoring power, that we should expect those outages to last 3-5 days.
So 3-5 day outages 2-3 times a year sounds like a right pain the ass, and certainly has me looking at adding a powerwall to our PV system. I had wanted one anyway for backup in the event of an earthquake or other event that might disrupt power for an extended time, but now we're almost guaranteed those outage events, rather than it being a hypothetical.
- sdrothrock 8y ago> has me looking at adding a powerwall to our PV system I'm not trying to raise FUD here and am genuinely curious -- would a powerwall-like system have its own set of issues or dangers in the event of nearby fires/evacuations?
- sxates 8y agoWell, I'm not sure what happens to it if your house catches fire - but if your house burns down I don't see how the battery could have made it worse. So I imagine scenario 1 is your house doesn't catch fire, in which case it's fine, and you have power even if the grid is down, or scenario 2 where your house does catch fire, and maybe the battery contributes to that, but it would burn down either way. But keep in mind that the 'red flag days' I'm describing where PG&E would cut power are not days where fires are actually burning in the area - just days where fires are more likely to start. They're shutting down their power lines so that if the wind knocks one down it won't start a fire. This is a response to last years devastating fires in Sonoma county, which were believed to have started by downed power lines in high wind and dry conditions.
- dsymonds 8y agoOne big reason for shutdown rules with home PV systems is to keep firefighters safe. If your house is on fire, the firefighters really don't want to be contending with high voltage electricity as well.
- gsich 8y agoProblem is that, as long the sun shines, a voltage will be generated. Depending on how they are linked together this makes it more or less dangerous.
- TheAdamist 8y agoI've been noticing ground level external emergency shutoff switches for roof based solar around my city, so i imagine its something thats been making its way into fire/electrical/building codes recently. They're unsecured as far as i have noticed, so i imagine the troublemakers will be pulling them sooner or later.
- dredmorbius 8y agoStored energy is stored energy. Batteries may burn, explode, spark (ignition source), electrocute, and/or be a source of noxious fumes or chemicals.
- sdrothrock 8y ago> But keep in mind that the 'red flag days' I'm describing where PG&E would cut power are not days where fires are actually burning in the area - just days where fires are more likely to start. Ahh, that makes more sense. I was thinking about situations where there would be fires burning in the immediate vicinity, so perhaps dangers from overheating (explosion?) or firefighters/emergency responders having to clear areas quickly, etc.
- msh 8y agoIf downed power lines are that big of a risk I would think that the correct solution would be to bury them instead of shutting down power.
- amluto 8y agoHaving tried and failed to work with Tesla for solar, I strongly suggest you skip the powerwall. Use LG Chem’s RESU instead. It’s slightly cheaper, and they are willing to let third parties install it. It pairs with SolarEdge’s StorEdge. If you want serious off-grid functionality, you need a beefier inverter. Outback sells such things, but the resulting system is a good deal more complicated.
- sxates 8y agoSolarCity installed the PV system, so I figured it'd be easier for them to continue with the upgrade. But it sounds like things are kind of a mess over in Tesla/SC land these days, so who knows...
- amluto 8y agoAnother factor is that the Powerwall 2 DC coupled model got canceled. And I don’t see how an AC coupled battery will give as reliable of a backup system without complicated integration with the inverter and without extra automatic switches that can isolate the battery from the loads. In particular, how does an AC coupled system handle the case where the battery was fully discharged before sunrise? The inverter needs to turn on when the array starts producing, but the battery can’t charge without the backed up loads being powered, and the backed up loads can’t be powered until there’s enough battery charge to supply the inrush current. A DC coupled system like the Powerwall 1, RESU, or pretty much any lead-acid system doesn’t have this problem at all.
- TheSpiceIsLife 8y agoOut of curiosity, what are your reasons for not using a generator?