Is 18k pv the cheapest battery to grid inverter?

[1201]

Just about any storage inverter will do this and there are plenty lower cost than the 18K pv or the Solark 15K

Of the top of my head and far from complete:

Solis 5G HVES ( 6kw backup )
Solis S6 ( just coming to market, 11.2kw backup top model )
Goodwe GW7600A-ES ( upto 11kw backup top model )
Growatt XH series ( upto 10kw Backup top model )
Generac ( do not recommend )
Solax X1
Tigo TSI ( looks like a relabed Growatt )

All of the above are less than half the cost, UL9540 certified. Note this are high voltage, not 48V and the UL9540 listings are for a small set of listed batteries, not DYI or flavor of the month rack batteries.

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Hey thanks. Where can I find info on the batteries for these? Are you based in the u.s?

 

[timselectric]

Well, IF one is connected to utility grid, isn’t the generator on a transfer switch connected to GRID input when PV AC coupled?

I suppose that could work. If the hybrid is in control of the transfer switch. Or at least the generator.

My only concern would be the AC coupled system backfeeding the generator. This would damage the generator.

 

[Danke]

My only concern would be the AC coupled system backfeeding the generator. This would damage the generator.

Yeah, I think I’ll give Sol-Ark a shout. I doubt I would have to use the generator as I’m going to put up a lot of panels. But if I do, I’d have it on a manual switch anyway to run when there’s no PV.

 

[timselectric]

Yeah, I think I’ll give Sol-Ark a shout. I doubt I would have to use the generator as I’m going to put up a lot of panels. But if I do, I’d have it on a manual switch anyway to run when there’s no PV.

I would say that you could put a transfer switch before the generator input. And switch between the generator and AC coupled system. But I don't think that the settings can be setup for that. I think that it's either one or the other.

 

[DIYrich]

My only concern would be the AC coupled system backfeeding the generator. This would damage the generator.

Supposedly the Sol-Ark can tell when the Grid Input has Grid or Generator. I'm guessing it has to do with how stiff the grid is.
If it senses Generator, then it won't allow power to feedback the Grid Input.

 

[zanydroid]

Still kind of uncomfortable without seeing a slide deck explaining the state transitions here to protect the generator in various situations… and what the chances are of blowing up the generator in an edge case (which wouldn’t be covered by the warranty limitations ? )

I guess if there are internal CTs on the generator lines the SolArk can have a watchdog monitoring the amount of power going the wrong way, that opens the relay and sends a shutdown trigger to the generator if the AC coupling algorithm goes south.

Grid in is probably guaranteed to have CTs for zero export which can be repurposed for this. Not sure about Gen In

 

[timselectric]

Supposedly the Sol-Ark can tell when the Grid Input has Grid or Generator. I'm guessing it has to do with how stiff the grid is.
If it senses Generator, then it won't allow power to feedback the Grid Input.

If it can do that. It would be a major plus.
It would be nice if it had a setting for "AC input is generator".

 

[zanydroid]

If it can do that. It would be a major plus.
It would be nice if it had a setting for "AC input is generator".

Can you trust users to set that correctly? ?

 

[timselectric]

Can you trust users to set that correctly? ?

Never lol

 

[zanydroid]

Never lol

Actually that’s an even better CYA for the warranty claim.

“We saw that you forgot to set it to generator. Sorry bruh”

 

[zanydroid]

To be clear, I think this can probably be implemented in a sufficiently idiot proof way based on the discussion in this thread (though more direct relay controlled inputs on the AC bus are always helpful)

What is the historical track record (across all brands) of AC coupling both a generator and grid tie inverters? That provides some empirical evidence of how viable it is in practice vs backseating it while sitting at a keyboard.

 

[Danke]

 

[timselectric]

View attachment 163250

Bingo
Questions answered.

 

[Danke]

Bingo
Questions answered.

So I guess there’s no concern about backfeeding generator? I did call Sol-Ark and left a message for a callback.

 

[zanydroid]

Might want to push for a more experienced support engineer from SolArk since this is an advanced topic with fewer inherent safeguards compared to just running off DC coupled PV.

 

[timselectric]

So I guess there’s no concern about backfeeding generator? I did call Sol-Ark and left a message for a callback.

It would appear so.
It's in their diagram.

 

[ChrisG]

You would need 2 for spilt phase and a pair of CTs. Then whatever batteries and charge controller you want to use. You could buy into the entire ecosystem if you wanted to but you only really need the two inverters and a pair of CTs to my knowledge.

I have a pair of 5kVA inverters in split phase. I've already picked up the CTs but I haven't done any testing yet.

I know there is a 18k thread on this CT main - panel backfeed - 0 sell topic. Really interested in your testing @Adam De Lay.

 

[DIYrich]

Bingo
Questions answered.

Page 11 of the manual shows on grid setup with generator on grid input. With off grid, you can say there is a setting to tell the solark what is on the input. With on-grid, the sol-ark has to figure out what is connected.

 

[timselectric]

Page 11 of the manual shows on grid setup with generator on grid input. With off grid, you can say there is a setting to tell the solark what is on the input. With on-grid, the sol-ark has to figure out what is connected.

I assume that if you don't set the input as generator. The other option is grid.

 

[Danke]