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Enphase AC coupling solutions - "tesla" or "sol-ark"

Bart1080

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WHy is one solution say a prepackaged solution better than a seperate component solution?
Ignore the brand (As a geneneralisation)

I've a Enphase micro inverter solar system 240v grid tied 12.7Kw Enphase system, Shed Roof mounted.. it cut my bills from $7,500 A year to ~$1,000 A year. We've had it for 8 months but lots of excess solar power going to waste and would rather self utilise it more with battery backup for power outages to run critical loads with the help of my gen set.

Looked at a Tesla pre-packaged type solution and at $15,000 would take 10 to 15 years to break even so not an option.

Our solar will payback in <3 years!

Installers only do a prepackaged commercial all in one "Tesla type" battery system.

So started to go down the seperate component DIY with some sparky assistance route looking for something more affordable with a pay back of < 4 to 5 years. However a 12 to 15kw inverter system with a small server rack battery isnt a big difference in price!!!!

WHAT AM I MISSING....As I thought it would be a big difference
I was kinda hoping for a solution <$5k, but that appears to be fairy land thinking :)

Is there a better approach?
 
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A single Tesla Powerwall is a good value compared to the other Tesla type batteries or a DIY. It is only when you can live with a 5kW inverter but want more battery capacity that real cost savings can be had. That does not mean the payback will be any faster. Also the DIY option is becoming less of an option as NEC 2020 is implement in local jurisdictions.
 
The NEC2020 isn't an issue here in Aus, its been regulated for decades.

The more I think about it, the more I'm favoring a seperate component system from a self maint perspective as at some point something will fail and in theory cheaper/easier to fix/replace/upgrade the faulty component

Maybe I'm over thinking it, .....maybe all thats needed is to start off with the smallest seperate component system and battery that will at least allow for me to run it as a backup system during the day during an outage.....and add batteries when it makes economic sense
 
The NEC2020 isn't an issue here in Aus, its been regulated for decades.

Texas is now under NEC2020 which means storage systems must be UL9540 listed ( inverter / battery tested, validated as a pair )

Legally now, you can not have a stand-alone system over 12V battery voltage thanks to NEC2020 which is adopted for your entire state
 
Legally now, you can not have a stand-alone system over 12V battery voltage thanks to NEC2020
I did not realize NEC 2020 had a voltage limit. Maybe you mean DIY is restricted to 12 volt? They are still doing Tesla Powerwalls?
I did not realize inverter and battery had to be validated as a pair? That would explain why Outback came out with Mojave.
 
WHy is one solution say a prepackaged solution better than a seperate component solution?
Ignore the brand (As a geneneralisation)

I've a Enphase micro inverter solar system 240v grid tied 12.7Kw Enphase system, Shed Roof mounted.. it cut my bills from $7,500 A year to ~$1,000 A year. We've had it for 8 months but lots of excess solar power going to waste and would rather self utilise it more with battery backup for power outages to run critical loads with the help of my gen set.

Looked at a Tesla pre-packaged type solution and at $15,000 would take 10 to 15 years to break even so not an option.

Our solar will payback in <3 years!

Installers only do a prepackaged commercial all in one "Tesla type" battery system.

So started to go down the seperate component DIY with some sparky assistance route looking for something more affordable with a pay back of < 4 to 5 years. However a 12 to 15kw inverter system with a small server rack battery isnt a big difference in price!!!!

WHAT AM I MISSING....As I thought it would be a big difference
I was kinda hoping for a solution <$5k, but that appears to be fairy land thinking :)

Is there a better approach?
You're missing using the battery nightly to offset what you're taking from the grid, and charge it from solar in the middle of the day. If your system offset your bill by $6500, then your rates are pretty high and the battery will not take 15 years to pay itself off. This is only with a grid-tied battery system. A cheap off-grid inverter + battery system can't do this, and so it costs more in the long-run.
 
Texas is now under NEC2020 which means storage systems must be UL9540 listed ( inverter / battery tested, validated as a pair )

Legally now, you can not have a stand-alone system over 12V battery voltage thanks to NEC2020 which is adopted for your entire state
I just read through NEC2020 706 and 710. The limit for an ESS is 100V inside a dwelling unit and there are exceptions allowed. I didn't see any reference that said it was limited to 12V. That's just not possible. It would collapse an industry!
What I did find was a change to 706.3, and this is BAD FOR DIYers if you're not "qualified" per the definition.

706.3 Qualified Personnel
The installation and maintenance of ESS equipment and all associated wiring and interconnections shall be performed only by qualified persons.
Informational Note: See Article 100 for the definition of qualified person.


706.5 Listing
Energy storage systems shall be listed.

710.6 Equipment Approval
All equipment shall be approved for the intended use in accordance with one of the following:
  1. Be listed for the application
  2. Be evaluated for the application and have a field label applied
Informational Note: Inverters identified as "multimode" and "stand-alone" are specifically identified and certified to operate in this application. Stand-alone inverters operate in island mode. Multimode inverters operate in either island mode (previously called "stand-alone mode") or interactive mode, if it has been installed with the optional utility grid connection. A multimode inverter will only operate in island mode if it is never connected to an electric utility supply. Stand-alone inverters are not evaluated for and are not intended for connection to export power in parallel with an electric utility.

706.9 Maximum Voltage
The maximum voltage of an ESS shall be the rated ESS input and output voltage(s) indicated on the ESS nameplate(s) or system listing.

706.20 General
(B) Dwelling Units

An ESS for one- and two-family dwelling units shall not exceed 100 volts dc between conductors or to ground.
Exception: Where live parts are not accessible during routine ESS maintenance, a maximum ESS voltage of 600 volts dc shall be permitted.


710.12 Stand-Alone Inverter Input Circuit Current
The maximum current shall be the stand-alone continuous inverter input current rating when the inverter is producing rated power at the lowest input voltage.

This is a good thing, and how it should be calculated.

Todd
 
You're missing using the battery nightly to offset what you're taking from the grid, and charge it from solar in the middle of the day. If your system offset your bill by $6500, then your rates are pretty high and the battery will not take 15 years to pay itself off. This is only with a grid-tied battery system. A cheap off-grid inverter + battery system can't do this, and so it costs more in the long-run.
Tks Todd.
Rudimentary calculations:
  • annual electricity cost with solar now is approx $1,000
  • Tesla 10Kw battery a.c. coupled, batt backup is $15,000
  • If I could become effectivily grid indipendant which is unlikely with this set up then best case is 15k/1k = 15 years ?
I'm a 100% electric house, tank water, septic, sand filter electric hotplates & oven etc and I'd doubt the 10kw battery would supply 100% of my normal day to day evening requirements. ...then by 15 years, what's the capacity of the battery....has it got any life left in it after 4,500 cycles? Which is why I'm leaning towards a cheaper alternative to cater for power outages for daytime use until it's more economically feasible
 
Ouch. $15k for a Powerwall seems very pricey to me. My advice then is to just setup a backup loads panel with what you really need to power, then look at the watts and time in use and how long a backup you need, and go with that as the minimum. In that case, it's just for critical loads but honestly, batteries are expensive at any size the $/kWh is still way too high for my budget, but I was forced into it because my Enphase system wouldn't function without the battery, or else I needed a useless load controller I didn't need for any other reason.
 
but I was forced into it because my Enphase system wouldn't function without the battery, or else I needed a useless load controller I didn't need for any other reason.
...Why, are you referring to a grid outage scenario which would be the normal behaviour or something else?
 
...Why, are you referring to a grid outage scenario which would be the normal behaviour or something else?
No, I was going to build a Sunlight Backup system without the battery, but it requires 2 IQ Load Controllers, no exceptions, and no workaround. The only alternative is to add an Encharge battery. For my loads, the battery is useful, but the load controller is not.
 
No, I was going to build a Sunlight Backup system without the battery, but it requires 2 IQ Load Controllers, no exceptions, and no workaround. The only alternative is to add an Encharge battery. For my loads, the battery is useful, but the load controller is not.
Without a battery it needs to be able to do load shedding and for that it needs 2 load controllers.
Simple as that.
 
Without a battery it needs to be able to do load shedding and for that it needs 2 load controllers.
Simple as that.
Each load controller can handle 3 x 240V or 6 x 120V loads. I only have 3 x 120V circuits in my sub-panel. I don't need 2 load controllers, simple as that. They require me to buy something I don't need, and that upsets me.
 
Each load controller can handle 3 x 240V or 6 x 120V loads. I only have 3 x 120V circuits in my sub-panel. I don't need 2 load controllers, simple as that. They require me to buy something I don't need, and that upsets me.
I see it as that you didn't read the requirements before you bought the system and you try to blame them.
 
No, I was going to build a Sunlight Backup system without the battery, but it requires 2 IQ Load Controllers,


OK, so now you have my attention.

I was thinking of the same thing something along the lines of a "daylight" backup system for outages but with either no battery or a very small battery to minimise costs and negate the need for a genset to run all day plus run out 8 to 10 extension leads plus requires me to set it all up and start it as the wife struggles and then dealing with all the whining!! :).

I know I can simply install a network disconnect switch and gen plug (and will still need this function with whatever solution) which is where I'm starting to look at cheap options to utilise the solar during the day.

So what did you end up installing exactly?
 
OK, so now you have my attention.

I was thinking of the same thing something along the lines of a "daylight" backup system for outages but with either no battery or a very small battery to minimise costs and negate the need for a genset to run all day plus run out 8 to 10 extension leads plus requires me to set it all up and start it as the wife struggles and then dealing with all the whining!! :).

I know I can simply install a network disconnect switch and gen plug (and will still need this function with whatever solution) which is where I'm starting to look at cheap options to utilise the solar during the day.

So what did you end up installing exactly?
As I was saying, I got a little confused. The Enphase IQ8 inverters can form a microgrid, in combination with their System Controller, which has the automatic transfer switch, the neutral-forming transformer, and the brain of the system. A Sunlight Backup System requires 2 Load controllers, "OR" an Enphase IQ Battery. Where I got confused was in the training where sometimes it says 2 load controllers are required and sometimes it refers to just 1, I didn't understand the "one or the other" relationship. If there's a battery, you don't need any load controllers, or you can use 1 or 2, but if you don't it requires 2, even if your loads don't.

The Enphase Sunlight Backup with the Empower switch can do exactly what you want, but it's very expensive relatively speaking. And, Enphase requires the installer to be Enphase Storage Certified, which means their full training program. While it's not too difficult, there are a lot of misleading questions on the tests, and it takes a lot of time to go through them all to become certified. So either you go through the full training or you hire an Enphase installer. There are no workarounds.

No matter what system you decide to go with, the inverter must be sized per code to be equal to or larger than the largest load posted by the system it's connected to. In the case of Enphase, their microinverters are built into their Encharge battery products. They are the inverter. The IQ Battery 3T is limited to 1.28kW continuous, so you're limited to about 5.33A @240V. In your backup-loads sub-panel, the largest load must be < 5.33A. You can add more Battery 3Ts to reach 10.66A, 15.99A, etc. 3 of the IQ Battery 3Ts is equal to 1 IQ Battery 10T, which is 10.05kWh, and installed they run over $10k just for the battery/microinverter box, and cover. To make it all work requires a cellular modem, a Wifi comms adapter, and an Envoy that transmits data from the microinverters and the system controller to the cloud. The cloud connection is a requirement for their Warranty, it won't work without it.

To do what you'd like to do you need to add a backup-loads sub-panel and move the loads you want to run on the battery over to that panel. Just a few of them that you need as critical. If you don't do this, then the sizing of the inverter and the number of panels required will be prohibitively expensive, even when doing it DIY, in order to meet the code. I hear doubt that you can afford a large enough system to power your whole house, but before we know this, you will need to create that spreadsheet listing all the loads and how long they need to run during an outage. That's the first step to designing any backup system.

Best,
Todd
 
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