Grid Tie System with Standby Generator

[Sunking]

Hi Technoyogi

While my knowledge is very limited in solar, but I strongly feel that you should use a battery system than a Grid Tie.

You just lost all credibility with that statement.

[russ]

You just lost all credibility with that statement.

He is history already.

[SunEagle]

He is history already.

I guess if you ask the same question 100 times someone will give you the answer you are looking for. He always believed that the Solar GTI would see the Generator as "the grid" and keep on working along side the DG thus giving him enough power to run all his loads.

The anti-islanding safeties on a GTI seems to be outside the grasp of a lot of people not familiar with this technology no matter how many times you try to explain it to them.

[russ]

I guess if you ask the same question 100 times someone will give you the answer you are looking for.

This is a standard technique in his country - keep asking until you finally fund someone who says what you want. Then the other 1000 are promptly ignored and the agreeable fool given a promotion.

[inetdog]

TThen the other 1000 are promptly ignored and the agreeable fool given a promotion.

And asked to provide testimonials to potential investors, of course.

[russ]

of course.

One time I sat on a podium where the company was promoting a stock offering - I was told, "Don't say anything, we will answer for you". I was only there to show the foreign participation in the project meaning it was OK.

[GlennT]

Solaredge Grid Tie Inverter and Generac Standby Generator

Real simple, if you loose commercial power, the solar PV turns off, the automatic transfer switch (ATS) operates to isolate you from the grid as designed and to electrical codes, and the generator picks up the load in the house.

The PV system will not reconnect until commercial power has been restored for about 5 minute without interruption. Once commercial power is restored, the generator turns off, the ATS re-connects you back to commercial power, and then the PV system will turn on when all is clear

This is an old message I found while researching my situation, and I wanted to see if you still maintain it works this way. I've found conflicting information on how this may play out. How does the PV inverter differentiate between grid power and generator power? I've been told that my Generac power is "grid quality".

Thanks.

[Mike90250]

This is an old message I found while researching my situation, and I wanted to see if you still maintain it works this way. I've found conflicting information on how this may play out. How does the PV inverter differentiate between grid power and generator power? I've been told that my Generac power is "grid quality".

Thanks.

It Depends. Different brands have differences.
Grid Tie, the GT inverter just shuts off when the grid fails. The transfer switch isolates the house from the GT and the Grid, so the generator can power just the house (not the GT inverter)


For off grid:
My XW has a wider range of acceptance for AC2 (generator) than it does for AC1 (grid).

[GlennT]

[QUOTE=Mike90250;177964]It Depends. Different brands have differences.
Grid Tie, the GT inverter just shuts off when the grid fails. The transfer switch isolates the house from the GT and the Grid, so the generator can power just the house (not the GT inverter)"

But my GT inverter is not connected on the grid side of the transfer switch. It's on the house side. I think in this case, the generator would again provide AC power to the GT inverter and it may attempt to parallel with the generator. I'm just not sure what it will do.

[inetdog]

This is an old message I found while researching my situation, and I wanted to see if you still maintain it works this way. I've found conflicting information on how this may play out. How does the PV inverter differentiate between grid power and generator power? I've been told that my Generac power is "grid quality".

Thanks.

One way is that the inverter/charger has two AC inputs, one for grid power and one for generator power. The grid power input, AC1, has a transfer switch to disconnect the grid when it goes down and the inverter goes to standalone mode.
If generator power is available on AC2 the unit can be programmed to operate in grid-tie mode with the generator as the source. Since the unit is measuring current (and power) flow from the generator, the GTI output can be throttled back to prevent back feeding the generator. And any remaining solar power can go to the batteries.

Search the forum for "generator support" and you will find some very good threads on configuring this mode.
Not all hybrid inverters have this capability. Some Outback and some Xantrex/Schneider models do.

Just to clarify, there is a transfer switch on AC1 only, but the AC2 input would not be connected to the house lines (including the GT function) unless the AC1 transfer switch is open.
The difference is that when AC1 input goes away the inverter will work with or without an input on AC2, it will just work in a different control mode with it than without it.

[Mike90250]

But my GT inverter is not connected on the grid side of the transfer switch. It's on the house side. I think in this case, the generator would again provide AC power to the GT inverter and it may attempt to parallel with the generator. I'm just not sure what it will do.

If you connect a generator and a GT inverter together, on a sunny day, you are only safe for as long as your house loads exceed your solar power. If the spa heater cuts off, and the GTI attempts to push power into the genset, you get a lot of smoke, that is expensive. Yes, it may work for a short while, but most homes have less than 1Kw base loads.

[GlennT]

If you connect a generator and a GT inverter together, on a sunny day, you are only safe for as long as your house loads exceed your solar power.

That's the way it seems to me also, but sunking says it's just not a problem because apparently, the GT inverter knows the difference between generator power and grid power, and won't try to parallel with the generator.

You say you get a lot of smoke....but wouldn't the GT inverter (SolarEdge) recognize some type of fault condition and shut itself off, or open a OCPD?

[ButchDeal]

That's the way it seems to me also, but sunking says it's just not a problem because apparently, the GT inverter knows the difference between generator power and grid power, and won't try to parallel with the generator.

You say you get a lot of smoke....but wouldn't the GT inverter (SolarEdge) recognize some type of fault condition and shut itself off, or open a OCPD?

No it is a gamble. Sunking was mostly talking about bimodal inverters not straight GTI inverters like the SolarEdge. Your best bet is to move the interconnect to the other side of your transfer switch. If the Generator happens to put out good clean current for long enough the SolarEdge will think that the grid is back and turn itself on, and try to dump lots of power into the generator, thus causing smoke and blown generator.

[GlennT]

If the Generator happens to put out good clean current for long enough the SolarEdge will think that the grid is back and turn itself on, and try to dump lots of power into the generator, thus causing smoke and blown generator.

Ok, but are you speaking from experience, or conjecture? I would like to have someone chime in who's actually had an installation like mine and see what they discovered. Thanks for your input.

[ButchDeal]

Ok, but are you speaking from experience, or conjecture? I would like to have someone chime in who's actually had an installation like mine and see what they discovered. Thanks for your input.

I would hope that no one has an installation like yours as it is not the recommended way to install. Grid tie inverters should always be upstream of any transfer switch. Bimodal systems are a different story altogether.