I believe the push to UL 9540 is pushing us away from modular / open systems and to pre-architected solutions from individual vendors.
Great for being certain everything works and is safe.
Lousy for keeping costs down.
Hoymiles HYS-7.6LV-USG1 Hybrid Inverter
- Thread starter ncsolarelectric
- Start date
Great for being certain everything works and is safe.
Lousy for keeping costs down.
For high-power systems, I can see the value.
For <=10kW systems intended for average residences with modest-sized solar arrays and limited requirements for backup power, much less so.
zanydroid
Solar Wizard
With DC ESS coming back and <100V systems it could be OK. I think 48V has a shot at being both code compliant and
UL9540 3 ed does not standardize the safe operating contract between DC ESS and a 1741 inverter. It just gives some suggestions on how you can design a DC ESS & its installation instructions to maximize compatibility and openness.
For instance, there's nothing stopping EG4 from writing the instructions to make it really easy for them to qualify new inverters of their own with a DC ESS version of their batteries, but hard for other companies.
On the flip side, there's nothing in UL9540 stopping a progressive, DIY friendly DC ESS company from writing very lenient and easy to work with integration instructions. This could even be crowdsourced or something with help from a friendly / receptive manufacturer in China
zanydroid
Solar Wizard
Hmm, I don't follow the scenario here. Which relays arc? It sounded like you weren't going to use a MID with XWs.
How easy are the 200A relays in the Sol-Ark and LuxPower to replace? And what is the typical failure mode?
In what situations do you need the make/break? Disconnect due to anti-islanding?
Let’s hope.
A 48V UL9540DC ESS standard allowing any UL9540DC 48V battery to be used with any UL1741 hybrid would truly ops things up (and drive down costs).
In the meantime, I’m afraid we’re heading towards higher-priced full solutions (or at least qualified / certified UL9540 pairings)…
zanydroid
Solar Wizard
It gets tricky in a few ways. The Hybrid is on-grid so any PV changes is supposed to go through PG&E.
And then PG&E has a whole mess of ESS specific rules that are hard to understand. Broadly speaking they are OK with you exporting already approved solar power. For some of the ESS types you can register, they will model the amount of export that you are expected to be able to generate (these types are not able to report generation to PG&E)
I doubt they'll be able to detect the import side of this.
I suspect if they wanted to train a machine learning model or manually code something up they could detect suspected zero export, and then check your registered equipment to see if it supports it.
Which link was broken?
The PowerWall has a specific functionality & clear English explanation to do exactly the "time-shift + common sense" thing. It will sell up to an energy reserve for a power outage. (I included a screenshot of it). If you have a battery and either don't care about outage, will recharge from generator on demand, or have a really big battery, then it would be irrational to not zero export and then dump it all at max price.
zanydroid
Solar Wizard
I was pretty serious about the crowdfund idea. The idea leverages the fact that the regulations and standards are already friendly and do not require weird lobbying or politics to manipulate. Which isn't really a DIY crowdfunding thing
Collect like $50-100K from a bunch of people to get it done, and then it will exist on the market. Since DC ESS has the promise of an open platform there's a compelling story to excite people with.
The grid disconnect relay in the hybrid grid-tied inverter can ark if the inverters are stacked and the stacked power (either grid or backup) exceeds the break/carry current of the relay in a single inverter. Parallel stacked relays are limited by the break/make/carry limits of a single relay. Make is not an issue because inverters sync to the grid before the MID relay closes, so the make current is low. But the break current or 160A max on a fully loaded 200A panel could exceed the break limit if the relay break rating is less than 160A, can happen during EPO or a fault in the inverter. The thermo-magnetic 200A main breaker will trip at 160A.
zanydroid
Solar Wizard
Main breaker will have to run for a long time above 160A before it trips. I guess you did say fully loaded though.
What is the break rating of the 200A integrated relays?
If you are using the same upstream 200A OCPD regardless of the number of stacked inverters I don’t see how the stress on a single relay will go up with number of inverters. If you are going above 200A, sure.
I wonder if a smart panel on a low latency control scheme would help, it can kill the extra load that needs to break. If the load is really that big to risk busting the relay then the inverter can’t even carry it and will reset once it runs out of surge.
Also if the inverter is already synced, ie to export, it can carry before break.
What is the break rating of the 200A integrated relays?
If you are using the same upstream 200A OCPD regardless of the number of stacked inverters I don’t see how the stress on a single relay will go up with number of inverters. If you are going above 200A, sure.
I wonder if a smart panel on a low latency control scheme would help, it can kill the extra load that needs to break. If the load is really that big to risk busting the relay then the inverter can’t even carry it and will reset once it runs out of surge.
Also if the inverter is already synced, ie to export, it can carry before break.
A 200A main breaker will trip on thermo above 160A, and magnetic (short or major overload) above 200 A, the details including timing are in the Breaker Trip Curves.
Depends on the inverter and the manufacturer specs for the grid disconnect relay. Make/brake is 150A for the 2 relays in the Lux Power EG4 18kvp, looks like the EG4/Lux Power relays are exposed and can be replaced, for a good reason!
You're right, you can stack inverters with a 200A disconnect relay up to 200A total without the need for an external MID device. The fastest relay in a stack will be the first to make the current and the slowest will be the last to break. Also, relays bounce and open/close 3-4 time before settling at the final state.
Before deciding to use EG4 18 kvp check some of the feedback on this forum, EG4 18-kvp replaced with Sol-Ark 15k.
Let's focus on the objective of this thread.
IQ8's can only be AC coupled with hard PV on/off by non-Enphase ESS systems and Enphase ESS systems do not tolerate other inverters on the Enphase micro-grid.
Enphase has new 5P batteries that are priced around 3k, they are great for TOU because they do not require an IQ systems controller, but they are incompatible with the prior generation batteries and the prior generation IQ system controller (MID panel). And 100% surge for 3 sec is a joke imho. So a lot of Enphase ESS systems are stuck at the max 40 kWh energy limit with no path forward, so there are a lot of disgruntled Enphase users. Distributers need to close out the old Enphase systems and batteries inventory and sell these at discount.
zanydroid
Solar Wizard
Which chart are you looking at? Magnetic is the instaneous trip range in the tables and the sharp leg in the graphs. The graphs indicate non zero trip probability at 100% at 40C ambient, but with sample variation and variance it can trip at lower than 100%.
I think the individual wire sizes and current ratings are consistent with paralleling under NEC for combining to increase current. I don’t know how that applies to relays though.
Do the inverters that support both MID and CLP allow parallel connection to CLP up to the pass through rating? The current ratings there are too low under NEC for the wires to be paralleled for increasing current, but it might qualify for parallel for redundancy but same (pass through) current.
This would be useful to stack inverter capacity to match the pass through current rating
zanydroid
Solar Wizard
I’ve noticed that Enphase are the cheapest full inverter/battery that is UL9540, however I don’t think the battery itself is enough to implement self consumption.
Not sure what the minimum config for self consumption is. Is it just IQ controller?
I think microinverter as a starting point is just going to make surge hard to handle… in my head offgrid use is not what an Enphase system is for, it’s for primarily ongrid .
Enphase has always supported TOU with battery charging from PV and discharging for self-consumption on the IQ gateway, no need for the IQ system controller. An IQ gateway (aka Envoy communications gateway) is always required for an Enphase micro-inverter system, so you just need to add AC batteries. But a new CAN Bus COMMS KIT 2 is required which is not yet available for existing IQ gateways. Batteries can be located up to 250' away from the IQ gateway and/or main panel which is a major plus.
Adding "puny" B3T's was not cost effective in the past. Adding a single 5P battery might work now for 5kWh self-consumption at 4kW max, but adding two 5P batteries will be similar or more expensive than adding two 5k LIF batteries with an 8 kW grid-tied AC backup inverter which also provides off-grid battery backup.
I just wanted to point out that a single 5P is probably the lowest cost option to provide minimum TOU management.
Off-Grid? Enphase captured about 25% market share for ESS backup about a year ago, with ENPH stock at an all-time high on 12/22/2022. Then ENPH went downhill because of increased competition from better backup systems and slowing demand for Solar/ESS systems.
Agree, using micro-inverters as a starting point was not a good engineering choice. Look at Hoymiles, they do not use their off-the-shelf micro-inverters to build backup inverters.
zanydroid
Solar Wizard
Yeah, Enphase being the cheapest for anything is counterintuitive, but somehow this happens to be the case. I saw this last month when I saw some deals on new 3Ts. It is barely adequate for summer self consumption in some parts of California and may actually break even somewhat quickly. This is also “coincidentally” just above the tax credit threshold in size.
(Barely adequate performance is sort of my assumption for non-reliability, non-efficiency, non-installation speed aspects of Enphase equipment)
TDave00
New Member
Todd, I'm assuming these inverters are capable of zero export like the microinverters (with DTU)?
Any updates on your tests with the unit?
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ncsolarelectric
Engineering Support CEO
Yes, absolutely capable of that. Regarding testing, so far, so good. Everything is working great, thanks for asking. I haven't had time to make the video yet but I had a 1-Line diagram made up y'all can take a look at it. We just completed it. LMK what you think. I quoted this system yesterday for about $2/W, including panels, racking, and shipping.
lionpowerwall
New Member
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- Apr 21, 2022
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Thus Hoymiles AC-coupling to any brand gridtie of hybrid compatible?
lionpowerwall
New Member
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can you give pls the video in ac coupling you have been made for hoymiles, thus this inverter is good one? how about spare parts using are all branded one?
lionpowerwall
New Member
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any reply regarding my queries about Hoymiles thanks