Need help : want to ac couple to a Enphase grid tied.
- Thread starter X propane
- Start date
zanydroid
Solar Wizard
You and I have discussed this before.
Personally I think autotransformer red flag is from using them to make non-UL listed 230V overseas inverters work with 120/240
There are plenty of US UL listed autotransformers explicitly meant to form neutral for UL listed 240V solar inverter systems. So it seems fine unless inspector insists that they can only be used for the line diagrams / hardware combination documented by the manufacturer.
There are of course NEC clauses that might otherwise prohibit an AT install.
zanydroid
Solar Wizard
If you go for grid up only implementation, you will need to investigate whether the inverter can be configured appropriately to detect the excess solar production. This depends on the software and where/how CTs can be used.
Usually the AC coupling will be done on the Grid AC side of the hybrid in this case. You might be able to do it on Gen or loads AC side but that has the risk of allowing AC inverter to stay up when grid is down, due to your mis configuration or limitation of the hybrid.
Usually the AC coupling will be done on the Grid AC side of the hybrid in this case. You might be able to do it on Gen or loads AC side but that has the risk of allowing AC inverter to stay up when grid is down, due to your mis configuration or limitation of the hybrid.
zanydroid
Solar Wizard
How do you make sure an oversized AC system is not allowed to output when grid down? OP doesn’t want to buy the battery size necessary to absorb the size of his AC.
zanydroid
Solar Wizard
Is .5C essential? I think it depends on the AC coupling algorithm
If the algorithm can be told to average .5C but allow higher bursts while waiting for AC coupling to respond, I think higher is fine, up to the battery spec.
If the algorithm CANNOT be told to do that then one should stick to .5C. Likewise if there is no positive confirmation that the algorithm is sophisticated enough to do this.
6
629658
Guest
I think it has been well established that 100% AC coupled solar and ESS is difficult and most adopters have issues. To get a system that functions without manual intervention and dump loads at least 50% DC coupled Solar in necessary.
BentleyJ
Solar Wizard
What algorithm are you specifically referring to? When AC coupling with the Load Side of the battery inverter, excess PV production gets backfed into the inverter and rectified to DC to charge the batteries. Batteries being the dump load. The battery inverter cannot regulate the charging function when its going in the reverse direction.
That said, some newer UL1741 grid-tie inverters do have the ability to step down their output in say 20% increments based on frequency steps. The XW+ ramps up frequency in 0.1Hz steps until 60.5Hz is reached. My older micoinverters do no respond to these frequency steps, they shut down at 60.5Hz otherwise its 100% output. This scenario is still different then the inverter internally regulating charge current and voltage since the frequency shift is attempting to control the input power not directly regulate the DC output to the batteries.
zanydroid
Solar Wizard
OP is looking at grid-up. That should be stable, with the question of confirming that the hybrid inverter is capable of detecting the excess production and absorbing it. Which should be doable with a zero export control loop, that is capable of dumping into the battery. No rocket science here, and GTI will not shut down.
For off-grid: from looking at the forum data, I'd make a slightly weaker conclusion and wager that it's quite clear that a lot of hardware combinations have issues and are difficult to configure. Since this is a DIY forum, the data is biased to have poor coverage data coverage of hardware not commonly used by DIY (EG PowerWall)
For off-grid: from looking at the forum data, I'd make a slightly weaker conclusion and wager that it's quite clear that a lot of hardware combinations have issues and are difficult to configure. Since this is a DIY forum, the data is biased to have poor coverage data coverage of hardware not commonly used by DIY (EG PowerWall)
zanydroid
Solar Wizard
All 1741SA and above GTI should be able to step down, that's a core part of SA. So users attempting to AC couple to newer installations compliant with SA at least don't have to worry about this part in theory. In practice they still have to worry about making the Frequency-Watts configurations line up on the grid former and grid tie side. And perhaps there are some that are SA compliant but were never tested to work off-grid against a grid forming inverter for some quirky reason or other.
What do you mean when you say, the battery inverter cannot regulate the charging function when it's going in the reverse direction? What direction is that?
The algorithm that the Hybrid inverter uses to decide how much to absorb in battery vs export, and what % to throttle the AC coupling to (which reduces the amount of power that needs to be managed, hopefully to keep it within the limits of the battery charger and battery, without having to hard-disconnect the GTI's by opening a safety relay). I believe my post there specifically refers to the grid-down case where only battery (and not grid) are available as dump loads, emergency or otherwise.
Are they high frequency? How well do the handle inductive loads? $$$ these are close to sol ark price correct?
At least not this year. Really want to get a hybrid unit up and working before investing in more batteries.
zanydroid
Solar Wizard
I guess you are asking about inductive loads b/c you plan to eventually be able to operate with grid down and want to buy equipment compatible with it, even if it's not for this year.
EDIT: wanted to make sure bc for your initial grid up / time shift only requirement you can easily use an anemic storage inverter (mentioned upthread by 1-2 people), so it’s easy for readers to get confused.
I believe Outback Radian needs a separate MPPT so they ought to be priced lower to be able to compete vs the SolArk with its integrated MPPTs.
EnerSys owns Outback so it's probable that permitted installations will be pricy for a while. Due to my expectation that batteries would cost more due to the corporate structure. Since EnerSys is a battery company, so why would Outback be motivated to get a 9540 listing with non-EnerSys batteries, or implement communications / other features necessary if some 3rd party battery company wants to pay for a paired 9540 listing with Outback.
By comparison SolArk makes its money on the $$$ hybrid inverter and has a pretty large set of listed 9540 pairings with plenty of battery companies.
If you don't need permits or communications, you can hook up any battery you want, modulo theoretical implementation details like AC coupling being software locked to work worse (for no good reason) if there is no communications.
Last edited:
6
629658
Guest
I just got done with a re-inspection after ESS installation as well as to qualify for a state ESS battery rebate program. Approved for both. Trophy ESS did not require UL batteries. Everything else was UL. They focused more on the Sol Ark than anything else. Big ESS rebate check is in the mail.
zanydroid
Solar Wizard
Nice. Does your POCO care about how export control and power control is done? I was reading up on the rules under some NEM jurisdictions — they’re very anal, and in a quite complicated way, since they are worried about using batteries to cheat on NEM credits.
Turns out there are actually standards you can get validated in the NRTL that proves an inverter will not “cheat.” XW Pro has one of those listed on its certificate and I’m sure SolArk got the right ones to maximize their addressable market.
6
629658
Guest
Yes they were crazy about it. I had to go into my Grid Settings and alter ramp rates the voltages the reconnect time and the Q values. I’m just glad I bought the Sol Ark because all the variables they required were user adjustable and present. Im not sure they would have allowed it on the system without those setting changes. On the other hand I know one of their company engineers didn’t like it but eventually approved after I was able to intelligently respond to his questions.
I also think if your inverter is listed on the California Solar Equipment List you will have a much easier time of it.
Around here most of the ESS installs are Tesla and Generac and that is what they were expecting.
zanydroid
Solar Wizard
Wow, OK. Do they do this for all projects (seems ridiculously unscalable), or is this specific to using SolArk / ESS that they're not used to?
I don't think this kind of adjustability is available in microinverters.
One other thing unique to batteries is that theoretically the curve can be adjusted so that they absorb active power from the grid in some conditions. Although unless they're also going to give you the electricity for free at those times, this feels like something that will piss off a lot of people.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,535
Quite a range of ESS subsidies in California, $150 to $1000/kWh
www.solarreviews.com
It seemed to me that those of us who aren't financially in need won't get much.
Those with financial need can't afford to install and get the big rebates. Maybe installers will front the cost - the $800 to $1000/kWh range is supposed to give it to them for free.
I get battery storage for life support equipment (and probably most of these aren't approved for such applications.)
Otherwise, grid-scale will be more economical and less likely to burn your house down.
What’s new with California’s SGIP battery rebate in 2023?
The most recent updates regarding California's SGIP program - the largest solar battery incentive program in the U.S.
www.solarreviews.com
It seemed to me that those of us who aren't financially in need won't get much.
Those with financial need can't afford to install and get the big rebates. Maybe installers will front the cost - the $800 to $1000/kWh range is supposed to give it to them for free.
I get battery storage for life support equipment (and probably most of these aren't approved for such applications.)
Otherwise, grid-scale will be more economical and less likely to burn your house down.
6
629658
Guest
Well I also applied and have been approved for a state $300 per kWh ESS rebate. I think they were expecting the usual 10kWh power wall application. I’m sure I surprised them by applying for 95kWh.
Apologies for making this confusing, probably cause it's how I feel right now! Yes I suppose I am treating this like an off grid capable inverter as well. yes having a bit more capability down the road seems like a better idea to me. I would prefer to go off grid, but I'm poor. Does it make much sense to choose an anemic inverter that can be paralleled, then buy a second one in a year or so? So with the lesser wattage inverters they would supply all they can, and if not adequate for the load than the grid would supply the rest that is required correct?
Battery topic. I'm in the middle of a dyi Eve cell battery. BC I'm cheap.
Not sure if I need to be permitted, quite sure the utility company would rather I didn't do any of this!
Thanks for your help and hanging in there with me! Eric R.
Similar threads
