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Which 2022 hybrid solar inverters can do export from battery to grid?

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winny

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Oct 25, 2022
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I tried to search but not much showed up. "export from battery" turned up a lot of "zero export" results, which is opposite of what I need.

I'm about to install PV panels and a hybrid inverter. I already have about 50 kWh worth of cells. With night-to-day price difference skyrocketing here, buying cheap electricity at night to store in batteries and export during peak daytime hours would significantly offset the cost of/amortize a PV installation.

Which hybrid inverters available in 2022 can do:
  • Battery charging from grid.
  • Export from battery to grid.
  • Prioritize solar input between grid export and battery charging.
  • Externally controllable. (If the inverter doesn't know the hourly prices and tariffs for import and export costs or if I can't control it without manually clicking in some app, it simply can't do what I need it to do)
Looking at ~10 kW for three phase 230 V Y-connection, 50 Hz.
 
Any inverter that is approved to UL1741-SA is designed and approved to sell to grid. Schneider, Outback, Enphase, Sol-Ark, SolarEdge all have offers that do this but Enphase and SolarEdge have fixed battery options vs flexible. I’d strongly suggest you get a pairing of inverter and battery that communicate with one another.
 
TrueNorthSolar said:
Any inverter that is approved to UL1741-SA is designed and approved to sell to grid. Schneider, Outback, Enphase, Sol-Ark, SolarEdge all have offers that do this but Enphase and SolarEdge have fixed battery options vs flexible. I’d strongly suggest you get a pairing of inverter and battery that communicate with one another.
Click to expand...
but none of the once you mentioned are able to sell battery power to the grid...
 
Deye can sell from battery to grid ... so I would be surprised if Sol-Ark can not.

Selling First mode:

zero_export.png
 
TrueNorthSolar said:
Any inverter that is approved to UL1741-SA is designed and approved to sell to grid. Schneider, Outback, Enphase, Sol-Ark, SolarEdge all have offers that do this but Enphase and SolarEdge have fixed battery options vs flexible. I’d strongly suggest you get a pairing of inverter and battery that communicate with one another.
Click to expand...
Thanks! I need to look deeper into Schneider, Outback, Enphase and Sol-Ark.
SolarEdge had 5 kW max for both charging and discharging. Charging is fine as prices are low from about 23 to about 05, so plenty of time to charge slowly. 5 kW max export on an overcast day will be a limitation though since I can't really capitalize on peak hourly rate. Better than nothing though. SE requirement on very expensive optimizers and locked-in ecosystem may be a bigger problem. I talked to SE support but everything seems to go through cloud-based app, and I don't want to manually enter what it should do hour by hour. Batrium seems to do be able to fake LG RESU via CAN to make most CAN inverters tick.

Oh, and there won't be any ready-made battery in my case since I have about 50 kWh worth of salvaged cells. Deye had a strong point here since it accepted lead-acid batteries and from what I could read in the not-that-exhaustive manual, user configurable voltage levels for the battery.
 
houseofancients said:
but none of the once you mentioned are able to sell battery power to the grid...
Click to expand...
As an EE, this is a software lockout for sure. They need to have four-quadrant inverter towards the grid and bi-directional DC/DC between low voltage battery and the inverter DC-bus, so all hardware is there to do the export. A friend of mine connected a HV EV battery in his car to the PC input of his inverter. It exported happily to the grid, but the guy is certifiable crazy and I won't do anything like that...
 
mrzed001 said:
Deye can sell from battery to grid ... so I would be surprised if Sol-Ark can not.

Selling First mode:

View attachment 119439
Click to expand...
This is the only option I have found so far. Do you have any experience with it? Especially do you know if the fixed scheduling can be overridden from web, RS-232, RS-485 or similar? My computer (or Arduino, haven't decided) will download prices for the next day on wholesale market and run a script to calculate how to maximize profit which I need to feed into the inverter, at least once per day. Completely unknown brand to me but lo-and-behold, all their models are listed as grid certified in my country. Distribution seems lacking though...
 
The Solis 5G Hybrid does all these modes discussed, there are US and EU versions, beware that this is a UL9540 inverter and is designed to use listed HV batteries for the US market. EU version is 48V batteries
 
winny said:
This is the only option I have found so far. Do you have any experience with it? Especially do you know if the fixed scheduling can be overridden from web, RS-232, RS-485 or similar? My computer (or Arduino, haven't decided) will download prices for the next day on wholesale market and run a script to calculate how to maximize profit which I need to feed into the inverter, at least once per day. Completely unknown brand to me but lo-and-behold, all their models are listed as grid certified in my country. Distribution seems lacking though...
Click to expand...

There is the Solarman web cloud thing for it. Never ever tried that :)
Also RS485 is a possibility. But again never ....
For monitoring RS485 works with Solar Assistant. But to change settings ... good question.
 
With the 50hz requirement, where are you? Will the power company/whoever has say let you do this?

I've got a Schneider XW pro 6848 and it will sell to grid. I believe the Outback Radian series will too, but I don't know if those are available in your area.
 
Solar Guppy said:
The Solis 5G Hybrid does all these modes discussed, there are US and EU versions, beware that this is a UL9540 inverter and is designed to use listed HV batteries for the US market. EU version is 48V batteries
Click to expand...
I read though the manual twice. Didn't find any mention of export from battery.
 
400bird said:
With the 50hz requirement, where are you? Will the power company/whoever has say let you do this?

I've got a Schneider XW pro 6848 and it will sell to grid. I believe the Outback Radian series will too, but I don't know if those are available in your area.
Click to expand...
Sweden. All power companies except the island of Gotland is required to accept solar installations. Energy meters installed can already measure power in both directions.

The Schneider XW pro 6848 did mention both dumb lithium, lead acid and two-stage charging curve so seems very DIY friendly. I did not however find whether it could export from battery to grid, and 6.8 kW is small so I would need two. Pros and cons of splitting the battery pack in half for each. How do you do when you sell from battery to grid with yours? Can you set it via Ethernet, WiFi, RS-232 or similar?
 
Are you allowed to sell to the grid? The interconnect rules are kind of complicated where I am (California) and some ways of structuring the transactions are not in the allowed set. IIRC my POCO really, really does not like arbitrage (buy from and sell to grid) in the interconnection agreement types that I looked at (small scale residential). This is not a matter of net metering compatible meters or other technical concerns, it's purely regulatory.

You would also need the code compliant batteries to be available at a reasonable cost. The code compliant ones are not for the residential (or rather, non utility) market in the US. Which is really annoying, but it is what it is. Most server rack batteries are in the ballpark of economical for this case, but not code compliant. Utility batteries are economical and legal, but those entities abide by different rules.
 
Last edited:
zanydroid said:
Are you allowed to sell to the grid? The interconnect rules are kind of complicated where I am (California) and some ways of structuring the transactions are not in the allowed set. IIRC my POCO really, really does not like arbitrage (buy from and sell to grid) in the interconnection agreement types that I looked at (small scale residential). This is not a matter of net metering compatible meters or other technical concerns, it's purely regulatory.

You would also need the code compliant batteries to be available at a reasonable cost. The code compliant ones are not for the residential (or rather, non utility) market in the US. Which is really annoying, but it is what it is. Most server rack batteries are in the ballpark of economical for this case, but not code compliant. Utility batteries are economical and legal, but those entities abide by different rules.
Click to expand...
Rules differ between Sweden and California. Yes, as long as you are approved to export here, you can export as much as you want up to the limit of your fuse (comes in stepped tiers, 11, 17 or 24 kW). Exporting 30 000 kWh/year or more will however be above the bracket for when you get solar install incentives as the government wants to differentiate between small scale home solar and bigger commercial installations. Just picking the most expensive hours and squeeze in 29 999 kWh per year to do the export will still pay off the entire installation very quickly.

I already have the batteries. I just need a solar inverter that I can do what I need. So far, the Deye looks most promising with Schneider second. Deye, although unheard of here, have just about all their models on the official pre-approved list of inverters by some grid owners interest organization. Strange, but very welcome. It's not illegal to use any inverters not on the list, but you need to supply all relevant documentation (certifications) to your grid owner yourself, which isn't needed for the ones on the list.
 
Looks like you've reviewed your equivalent of the interconnect agreement, and it's more generous than what we're allowed to do. I believe you have a big enough kWh of batteries that tends to trigger additional building code rules around where I live, esp in urban areas. Although it's money-losing proposition anyway with minimum $0.70/Wh battery costs for the necessary class of battery -- 2000 cycles before breaking even is kind of nuts. In case this is not permitted, your buy/sell pattern would be very easy to use as evidence.

Anyway, I'm just mentioning this so you cover your bases with respect to the viability of the business fundamentals of your installation.

If you look around on the forum here you should be able to find info on how people got their hands on Deye inverters.
 
zanydroid said:
Looks like you've reviewed your equivalent of the interconnect agreement, and it's more generous than what we're allowed to do. I believe you have a big enough kWh of batteries that tends to trigger additional building code rules around where I live, esp in urban areas. Although it's money-losing proposition anyway with minimum $0.70/Wh battery costs for the necessary class of battery. In case this is not permitted, your buy/sell pattern would be very easy to use as evidence.

Anyway, I'm just mentioning this so you cover your bases with respect to the viability of the business fundamentals of your installation.

If you look around on the forum here you should be able to find info on how people got their hands on Deye inverters.
Click to expand...
Thanks! If the rules would change in the future here, it would still pay for itself, it would just take longer so less ROI. Plan B is to charge on cheap electricity during night, use it myself during daylight hours and force the inverter to export the solar to the grid and use battery to offset my own needs. This will however require an even larger inverter as more power needs to be transferred though it. Plan C is to use UPS to cut house needs during the most expensive hours to make sure all solar power is exported to the grid.

Ironically, the situation is opposite of California with duck-curve (I believe it's called) pricing here except for summer weeks when the industry is closed down, i.e. they price peeks during lunchtime when solar irradiaton is the highest. Don't know how long this situation will last so better capitalize on it now. State grid here had plans for more interconnects to minimize price difference between different electrical zones, but it's currently projected to be completed in 2036 and new nuclear power plants are probably also in the late 2030s.

Batteries will be installed in either fire-proof housing or its own shed away from any building along with the inverter next to it.
 
I think here duck curve talks primarily about the increase in solar proportion of power mix during the day, which is noticeable in all seasons. The price tiers are aligned relatively well with it, with the peak and super peak applying most meaningfully in the summer. Most of the electricity load and high costs is in the summer due to AC use in the hot parts of the state. Not that much electric winter heating due to the high cost of electricity (you need solar with net metering over 12 months to make it economical vs gas. I may regret converting to a heat pump once net metering goes away).

A lot of residential installations after solar users were forced into this duck curve aware peak pricing actually put some panels optimized for western exposure to generate more during the afternoon peak and evening superpeak hours. Rather than optimizing for max total generation.
 
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