Help converting an existing grid tie system to battery TOU shaving

[goldserve]

I have an existing solar setup that was commissioned in 2014 that uses 16 REC-260-PE, 2 x 8 in a string on a SMA Sunnyboy 3800-TL-US. Seeing how my local utility PGE decided to sunset my plan and introduce TOU hours that are not friendly for solar generation, would it make sense to convert the solar inverter with 48V battery support to use excess solar to charge battery and supply power to the house during peak hours? I have the following questions as I am a newbie around here.

1) What is the current topology of the SMA inverter? I know it is 240V but does it do split phase?
2) What cost effective solar charger, inverter, battery charger should I replace the sunny boy with if I plan on getting 1 or 2 SOK/EG4 battery system to run in parallel?
3) Which above inverter would allow TOU setting, preference to charge battery with excess solar, output power from solar (if battery fully) and battery combined to reduce peak usage from grid, charge battery to xx% during off-peak? I think Sol-Ark does this but the 5K one costs so much!
4) Any other models have a feature similar to the SMA SMPS (secure power outlet in the event of outage)
5) Allow for off-grid operation if I plan to split some essential loads in a sub panel to use the battery in the event of outage?

Thanks so much for teaching a newbie here!

 

[goldserve]

Is the sol-ark the only product that checks all the boxes above? It’s a really expensive hybrid inverter!

 

[ramseyjack]

I am also on the quest for ANY TOU arbitrage hybrid inverter that can be put on the CEC list. The Sol-Ark is a DEYE inverter but at a substantial markup. I understand the support costs, just hard to stomach after 4 or 5 installs... Growatt does not seem interested in selling their low voltage unit that is on the CEC. I tried to order it (Growatt SPH3000~6000TL BL-US) from Signature, but the reply is simply, we don't use that model. I 100% understand but frustrating when know there are units out there that can work.
GSL (GSL-H-8KLV-US) sells a version that is pretty close, but again have to get off Alibaba and not on the CEC list.
Here in California, just need a unit that has enough logic to charge battery off solar only, send the excess to the grid the rest of the time, read CT's, and do self consumption ONLY (4-9pm). A little more complex than that for solar still producing until around 7pm in California in the summer, but you get the idea. They have been doing this in Hawaii for a LONG time.
I don't give up.. I will find a reasonable piece and do the CEC (California Energy Commission) approved list. or find someone that will sell me the Growatt SPH3000~6000TL BL-US

 

[BentleyJ]

For California, you will need a UL1741SA approved inverter. If you already have an existing grid-tie system then AC coupling is probably the easiest option to get a TOU system up and running.
Take a look at the new Outback Mojave and also the Schneider Conext XW Pro. There is also the possibility of going with a Enphase IQ8 microinverters.

 

[onokai]

Hybrids do all those things you asked for well as they a designed to be flexible-they all seem to be a bit more spendy than say the old school inverters that only do one thing.. my take is you pay for that.

12-15 years ago I took a solar night class at local university-panels cost $1200 each and sunny boy was the inverter of choice around here. No backup batteries or time of use options back then . Most systems cost big $$ and where small by todays standards back then.And no home user installs as well back then.
Now panels can be under 200$ each and hybrids can do most anything you want and can even accept new tecknologies of batteries in the future.They do cost more but what you get seems alot more to me.Solar back then was very inflexibale not so much anymore and Hybrid inverters are one of those big reasons. I'm liking the fact that in these inverters you can take extra power yoiu are not using and divert it to use-The Sol-Arc calls it smart load -others may use other terms but g=feeding my water heater with power I'm making thats extra on top of my house /studio loads is a great feature. Ok I am a Sol-arc user as well.My 2 cents

 

[AntronX]

How about forgetting grid-tie altogether and going with 48v battery system powering dedicated loads while using grid as a backup source to charge batteries during off-peak hours? Would you save money by going to basic consumption only non solar plan?

 

[goldserve]

In my case, because of how the system is currently wired, it would be hard to make a dedicated loads panel so I would just like to put a battery storage system In between the sma and grid to pull and push to my house as needed to shift the demand. I am open to keeping the existing sma and using ac coupling (I believe that’s what you call it) and having a smart battery charger and inverter that is grid tied. Most of these I found requires ac input1 (solar inverter) and ac input 2 (grid) and ac output (needs to be split phase 240V) and 48V DC of course. Is there no battery inverter that just takes 1 AC in and 1 240V split phase AC in or out like a grid tied solar inverter?

 

[AntronX]

How about one of these all-in-one inverters? https://www.mppsolar.com/v3/hv6048wp/
There is a thread about it here: https://diysolarforum.com/threads/new-all-in-one-mpp-lvx6048wp-ul-certified.23505/

 

[goldserve]

Definitely looks interesting. Waiting for more availability and testing from people. If I read it correctly, the firmware doesn’t implement external CTs to allow the inverter to push back power onto the grid via ac input yet?

 

[400bird]

In your shoes I'd be looking at adding an Outback Radian inverter/charger.
Assuming your current Solar Inverter supports the UL1741 frequency shift, I'd leave it, no reason to pay for a new one integrated into an All-in-One, when you've already got a working inverter connected to the panels now.

I added a Schneider XW pro, it works great and should be reliable considering the vendor. It doesn't AC couple "properly" out of the box, a couple of us are using them with an external controller to control charging from AC.

 

[Batronca]

Outback Skybox is good too. AC coupling or add more PV

 

[goldserve]

The outback inverters command a hefty price. Not even sure I can recover the cost from just shifting demand.

 

[400bird]

If Outback is too expensive, how are you discussing Sol-Ark?

 

[AntronX]

Can you describe new TOU pricing your utility is implementing? I am curious to calculate financial return of time shifting.

 

[BentleyJ]

Can you describe new TOU pricing your utility is implementing? I am curious to calculate financial return of time shifting.

With SCE (PG&E and SDGE are similar but they all have their own versions) There are 3 basic TOU plans. Prime is for electric vehicle owners, TOU 5-8PM and TOU 4-9PM summer rates are 66 cents and 53 cents respectively per KWh weekdays during the summer, June - September. Fortunately, so far SCE is still honoring the original 2011 NEM 1.0 fixed rate metering. They did try and pull a "fast one" recently where they sent out a letter with a form that had to be filled out and returned by a certain date otherwise they would have AUTOMATICALLY converted existing NEM 1.0 customers over to TOU. Glad I didn't just throw that piece of mail away without looking at it.

 

[AntronX]

WOW, here I am trying to DIY grid-tie system for less than 3 year payback with our 12 cent per kWh rate. With those kind of prices my $3k 5 kWdc system would be a money printer.

 

[BentleyJ]

Ya, I anticipated this happening in CA so I'm ready when they finally force us to TOU. The Schneider Conext XW+ 6848 does a fairly good job with Peak Load Shaving. It doesn't eliminate usage during the time period 100% but cuts it by 85 to 90%.

 

[onokai]

In California we have a few large utility companies -In the south it Southern Califonia Edision If I reacall right?San Diego may have thier own utility as well?
In the top 2/3 of state its Pacific Gas and Electric
Both have high electric rates. In the north (my area) we all have TOU meters and the high rate times are 5-8pm

 

[400bird]

The Schneider Conext XW+ 6848 does a fairly good job with Peak Load Shaving. It doesn't eliminate usage during the time period 100% but cuts it by 85 to 90%.

That's load shave, sure but you could also use "grid support" and program it to push current out to the grid. You could set this at 0.1 amps and it would take you down to 0 import. I've got mine set up to export 1 amp minimum for the entire "peak" TOU time.

 

[BentleyJ]

That's load shave, sure but you could also use "grid support" and program it to push current out to the grid. You could set this at 0.1 amps and it would take you down to 0 import. I've got mine set up to export 1 amp minimum for the entire "peak" TOU time.

We have an AC coupled system so Grid Support function is really not relevant in our situation. That said, we typically do export excess grid tie power up until about 7 pm or so. Some of our panels are on a West facing (250 degrees) roof.