Forget 'Baby on board'

[Ron Selzer]

My system automatically disconnects, to prevent injury to linemen. But there are several big honkin disconnects on the system, which even if I flipped, the system supposedly does not supply any energy to the house if the utility is offline. They call this Islanding.

That being said, why couldn't a couple of big contactors that would flip and prevent energy to being sent back to the utility be able to be installed and prevent that. Really not a big deal, but supposedly illegal here. Yet if you have backup battery system, it can operate with no utility power. Not sure how they do that.

They are called transfer switches commonly used with generators. If your system automatically drops out, sure seems like it could be stand alone.
Automatic Transfer Switches - Electric Generators Direct
Ron

[Bill Howatt]

I really don't know for certain, but I'd be wary equating a transfer switch for a generator with the requirements for a solar source that is feeding power all the time. If the solar connected only when the power failed then it would be acting like a generator installation but I don't believe that is how it is done.

[Alan Lightstone]

I can see issues with a solar installation, even as large as mine, being the sole provider of power during all the daylight hours. Production is a bell curve, and early morning and early evening it would clearly not produce enough energy for even selected loads in the house. On the other hand, if it charges batteries, and they produce even amounts or sufficient amounts of energy, it would not harm appliances.

Early morning, and early evening would act as brownouts.

But I really want my solar cells to be able to charge the large battery bank of a Cybertruck, which then could provide power to the house, even after sunset during a blackout.

[Ron Selzer]

I really don't know for certain, but I'd be wary equating a transfer switch for a generator with the requirements for a solar source that is feeding power all the time. If the solar connected only when the power failed then it would be acting like a generator installation but I don't believe that is how it is done.

Alan stated that the solar disconnects when Utility Co. power is lost. Also he has several disconnects already. Now it would be possible to install an Automatic Transfer switch OR a manual transfer switch to totally disconnect off of the incoming Power Lines and use the Cybertruck to power the house. OR might only need some more control circuitry.
DEFINITLY WOULD NEED LOOKED AT CLOSELY TO MEET LOCAL RULES.
Somebody would have to get up close and personal with what is there and design what is needed. Probably lots more money, however only Alan can say how much it is worth to him.
Ron

[Brian Elfert]

Most grid tie solar inverters need a source of power to sync to. Even if you had a transfer switch to isolate your solar the panels won't produce any power. This is starting to change. The latest Enphase microinverters can produce power even if the grid is down.

[Jim Koepke]

Does anyone actually think this all hasn't already been worked out by the power companies? When my neighbor installed solar panels the power company installed equipment so they could provide power to the grid.

The only real problem would be if someone is trying to instal solar and connecting to the grid without the power company knowing. Those are likely the ones who end up with a pile of ashes where their home once was.

jtk

[Alan Lightstone]

Does anyone actually think this all hasn't already been worked out by the power companies? When my neighbor installed solar panels the power company installed equipment so they could provide power to the grid.

The only real problem would be if someone is trying to instal solar and connecting to the grid without the power company knowing. Those are likely the ones who end up with a pile of ashes where their home once was.

jtk

Jim:

I think you are misunderstanding the issue. I provide a nice surplus to Duke Energy, for which they pay me <1/4 what I would pay them. On virtually every sunny day I send power to the grid.

It's when the grid goes down, and I want to have my large solar array provide my house with power that it is blocked.

Ultimately, some form of battery backup will be necessary. Tesla will have their Cybertrucks able to provide power to a house. Not available yet. But when it is, that's my battery backup. My question, which no one at Tesla can/will answer is whether or not my solar array can recharge the Cybertruck batteries when the grid is down.

[Bill Howatt]

If your solar array can provide the Kw capacity I don't see why it can't charge the battery assuming somewhere in your equipment is an accessible inverter outlet that converts the solar DC into 240V, 60Hz AC.
If the power (Kw) available from either array size of poor sunlight is low then isn't it just an issue of taking longer? But I can't say if Tesla puts any quirks into a generic situation.

[Alan Lightstone]

If your solar array can provide the Kw capacity I don't see why it can't charge the battery assuming somewhere in your equipment is an accessible inverter outlet that converts the solar DC into 240V, 60Hz AC.
If the power (Kw) available from either array size of poor sunlight is low then isn't it just an issue of taking longer? But I can't say if Tesla puts any quirks into a generic situation.

Oh no doubt it would be physically capable of charging the car batteries. The question is whether or not their system (it will be proprietary) will allow it. Especially as Tesla Solar did not install my solar array and it is not their inverters. There are devices that they say will be necessary to install to use the car to power the house.

Tesla calls it Powershare Home Backup and there is something about a Gateway V3 adapter/device. That's really about all the information that they say on the Cybertruck order website.

[Bill George]

It would be possible to install an another Inverter in parallel to to the existing just to feed a 240 circuit that only feeds the Tesla charging station, not connected to the grid. I could do it to mine if needed.

[Jim Becker]

Alan, how would a traditional fossil fuel generator be handled in this situation where you have solar as you describe with the draconian prohibition of using it during a utility power outage? In essence, a battery "generator" is what would fit in that same space.

[Alan Lightstone]

Alan, how would a traditional fossil fuel generator be handled in this situation where you have solar as you describe with the draconian prohibition of using it during a utility power outage? In essence, a battery "generator" is what would fit in that same space.

A propane generator (we have a tank here, but no natural gas available) would be able to power the house during a grid blackout (automatic or manual transfer switch). The solar panels, I believe, would again not be usable during the time the grid is out.

If at all usable, I would think they would have to supplement the generator output, otherwise that brownout scenario would occur. Not sure how equipment would handle that scenario. Certainly not technologically impossible, but I don't think fossil fuel generator companies (Generac, etc...) would have any interest in that.

[Jim Becker]

A propane generator (we have a tank here, but no natural gas available) would be able to power the house during a grid blackout (automatic or manual transfer switch). The solar panels, I believe, would again not be usable during the time the grid is out.

If at all usable, I would think they would have to supplement the generator output, otherwise that brownout scenario would occur. Not sure how equipment would handle that scenario. Certainly not technologically impossible, but I don't think fossil fuel generator companies (Generac, etc...) would have any interest in that.

Generac actually has an excellent battery backup solution...I considered it for here (along with solar panels), but in the end, I decided we would not be at this property for long enough to make it worth the investment, at least for us. They use the same automated transfer switch as with the gas powered generators (which I did opt for, having an all electric house other than oil backup on the heat pump) so that potentially would be a solution you could use. During normal times, the solar panels could keep the battery array topped off and if the utility goes down and they shut off your panels, you still have power. It's just coming from a bunch of very heavy batteries rather than from a traditional generator.

[mike stenson]

Most grid tie solar inverters need a source of power to sync to. Even if you had a transfer switch to isolate your solar the panels won't produce any power. This is starting to change. The latest Enphase microinverters can produce power even if the grid is down.

Those must be newer than a year.

[Steve Demuth]

Those must be newer than a year.

They've been available since 2021 from Enphase. If you have IQ8 inverters, those are grid-forming capable. Whether or not, and when, they will provide AC power absent grid input depends on how they're configured (which of course depends on what your utility will permit).