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drees
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The Enphase Energy Management System

Wed Oct 22, 2014 1:42 am

Seems to be a good number of Enphase users here - just saw this product announcement which is intriguing:

The Enphase Energy Management System

The key appears to be the Enphase AC Battery - a 1.2 kWh block of batteries with a bidirectional inverter inside that also plugs into an Engage cable so you can scale the system up to the desired size - or easily expand to the system over time.

http://enphase.com/wp-uploads/enphase.c ... hure-1.pdf

It's unclear as to what the actual power capabilities are as it lists two - 275W and 550W. Perhaps one is a maximum charge rate and the other is a maximum discharge rate?

It'll be interesting to see how much this costs. I'd love to have even 5 kWh of battery that I could easily plug into the house to shift demand outside of peak hours.

1.2 kWh storage blocks does seem a bit small to me, though. 2-4 kWh storage blocks would seem to make more sense for the typical application - I can't see people wanting less than a couple kWh of storage at a time. I'd love to see how they came up with the specs of the system.
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DNAinaGoodWay
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Re: The Enphase Energy Management System

Wed Oct 22, 2014 1:51 am

Nice.

System is modular and expandable in 1.2kWh increments.
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Re: The Enphase Energy Management System

Wed Oct 22, 2014 8:15 am

Eliiy Power makes the battery packs, anybody ever heard of them or know details of the packs?
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Re: The Enphase Energy Management System

Wed Oct 22, 2014 8:28 am

Happy to see Enphase has been working on big things. I d been waiting for them to have big annoucements.

Don't see mention of using this for backup power but surely they'll have a automatic transfer switch feature.
So does current TOU pricing allow one to have potentially good ROI? First covering their roof with PV and then if there is any remaining peak usage adding enough battery capacity to cover a chunk of it to be recharged during off peak?

I'd love to see some napkin math on how this would work out.

I wonder how this compares to this. Haven't seen any technical details on it though Tony Williams has the SolarCity/Tesla battery module.

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Re: The Enphase Energy Management System

Wed Oct 22, 2014 12:12 pm

I've been off the Enphase site for quite awhile. I agree, it is nice to see that Enphase is still innovating new products. The ENVOY-S looks interesting, and according to the link provided by the OP, Enphase is partnering with NEST. These promise to add some interesting system integration capabilities which I would greatly welcome.

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Re: The Enphase Energy Management System

Sat Oct 25, 2014 11:47 am

drees wrote:It's unclear as to what the actual power capabilities are as it lists two - 275W and 550W. Perhaps one is a maximum charge rate and the other is a maximum discharge rate?
It seems to be based upon a new microinverter called the S275. So I'll assume that you have the option to include either one or two of these microinverters per AC Battery.
drees wrote:1.2 kWh storage blocks does seem a bit small to me, though. 2-4 kWh storage blocks would seem to make more sense for the typical application - I can't see people wanting less than a couple kWh of storage at a time. I'd love to see how they came up with the specs of the system.
1.2kWh is about 50% of the production of a single PV module (300Wp) on a good day (and a larger percentage of the production of an average day). With the capability of 550W of bi-directional(?) inverter power perhaps one of these AC Batteries can be used to load- and source-shift the energy from every pair of PV modules in a system? That would produce a battery with the full generation capability of the PV array and storage for about 25% of one (peak) day's production.

It all seems pretty expensive to me, but it would be nice to see solar PV be able to address the evening (and morning) load peak. The good news is that as time goes on, the capacity of a battery with the same weight and price will increase. This seems like a positive step in that direction.
QueenBee wrote:Don't see mention of using this for backup power but surely they'll have a automatic transfer switch feature.
I think it all depends upon how the S275 differs from the M250 microinverter. I suspect one major difference is that it has a four-quadrant power converter which allows power flow in either direction. But all Enphase microinverters have had current sources as outputs and depend fully upon the grid to produce the voltage waveform. I suspect Enphase may have standalone operation as a future goal but that the first version will focus on load- and source-shifting. They need to ensure that they achieve extremely high MTBFs for modular components such as this.

In any case, since we have flat electricity rates here, I doubt this unit will have much utility for me.

OTOH, one feature which might be interesting would be to prevent peak generation from exceeding the state-mandated residential maximum. In my case, that would allow installation of these AC batteries to limit generation to 10kW while allowing a homeowner to install as many kW of generation as are needed to fully meet my load requirements. Such a capability should not be too difficult to implement.
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Enphase Inverter Measured MTBF: M190, M215, M250, S280

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DNAinaGoodWay
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Re: The Enphase Energy Management System

Sun Oct 26, 2014 8:07 am

Even without solar, if you could charge them at super off peak rates, and use that energy during peak rate times, they could pay for themselves.
'12 SL last reading @ 2 yr, 22k, 260 GIDs, 62.35 Ahr

'15 SV w/QC, Mfd 5/14, Leased 8/14, 292 GIDs, 64.38 Ahr when new
@ 36 months, 34k, 270 GID, 57.49 Ahr

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drees
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Re: The Enphase Energy Management System

Sun Oct 26, 2014 12:53 pm

DNAinaGoodWay wrote:Even without solar, if you could charge them at super off peak rates, and use that energy during peak rate times, they could pay for themselves.

Could it? Let's say that the battery in a 1.2 kWh module costs $300 ($250/kWh) and the inverter costs $100 for a total of $400. I think this price is probably low, but let's go with it.

Let's say that the battery is designed to last 10 years, but let's ignore capacity loss over time and let's also assume that the inverter is 95% efficient so your round trip efficiency is 90%.

We're also going to assume that you can get a full cycle of the battery every day, 365 days/year and that there are no vampire losses on the unit and that you don't have to worry about interest or anything on the money used to buy the battery.

That gives you 3650 cycles to recoup your investment of $400, over 10 years which means that you need to net $0.11 / day.

Taking into account 90% round trip efficiency, that means that you have to sell each kWh at a profit of at least $0.10 to break even.

Here in San Diego under SDG&E on either EV-TOU2 (whole house EV) or the DR-SES (solar net metered), this is currently not possible during the Winter (Nov-Apr) TOU rates - the spread between off-peak and peak rates is only $0.03 / kWh at the most. In the summer (May-Oct) there's about a $0.30 spread between peak / off-peak rates. So you might make $60 / year here in San Diego getting you to break even some time after 6 years. If the utility lets you install them and use the grid to charge the batteries (the utility is very reluctant to do so).

That's an optimistic scenario. In the majority of the country there will be no economic incentive to install these unless they can also provide backup power when the grid goes away completely.

Storage does open up a lot of opportunities for load shifting. For EV quick charging this is absolutely necessary to make economic use of the grid - just look at how Tesla is moving to install grid storage at each of it's Superchargers, especially in states with high demand charges.

In the short term I think it's quite possible that the utility company will look to using these for demand response, frequency regulation and reactive power support. If the system is designed to be remotely controlled by the utility, it's possible that 1.2 kWh of storage could provide a lot more value to the utility than the energy value alone. But the big issue again is that I feel that 1.2 kWh building blocks are too small to be economical.

BTW Reg - insightful post there a couple posts up.
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RegGuheert
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Re: The Enphase Energy Management System

Mon Nov 03, 2014 5:05 am

RegGuheert wrote:
QueenBee wrote:Don't see mention of using this for backup power but surely they'll have a automatic transfer switch feature.
I think it all depends upon how the S275 differs from the M250 microinverter. I suspect one major difference is that it has a four-quadrant power converter which allows power flow in either direction.
This article confirms that the new S275 micro inverter allows bidirectional power flow:
PV Magazine wrote:This system will work with Enphase's 5th generation S-Series microinverter, which offers a 97% CEC efficiency. It also offers full bi-directional power flow, which when combined with the advanced functions like supply of reactive power will provide more services to the grid.
I wonder: Will owners of S275 microinverters be able to go to their Envoys and turn on a new "Snow Melt" mode?
RegGuheert
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2011 miles at purchase. 10K miles on Apr 14, 2013. 20K miles (55.7Ah) on Aug 7, 2014, 30K miles (52.0Ah) on Dec 30, 2015, 40K miles (49.8Ah) on Feb 8, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

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Re: The Enphase Energy Management System

Mon Nov 03, 2014 10:51 am

RegGuheert wrote:]I wonder: Will owners of S275 microinverters be able to go to their Envoys and turn on a new "Snow Melt" mode?


Now, THAT would be a great enhancement! My panels are mounted on a relatively flat (and slick metal) roof, so it takes a while for the snow to melt off my panels. I tend to come up short on production in the winter, partially due to snow cover.
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