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Enphase IQ8 Update...


  09:14:00 pm, by Jim Jenal - Founder & CEO   , 1625 words  
Categories: All About Solar Power, Residential Solar, Ranting, Energy Storage

Enphase IQ8 Update... UPDATED

UPDATE - We got a message back from Enphase about a viable approach to the whole-house connection issue discussed below.  

The end of March found me in San Diego attending the annual NABCEP Continuing Education Conference.  As part of being NABCEP certified, I am required to recertify every three years, and my third recertification occurs this year.  The Conference is a convenient way to earn the credit hours needed as part of the recertification process. 

While much of that is bone dry (such as a full day talking about the most recent changes to the National Electrical Code, made tolerable only by the wit of the presenter, Ryan Mayfield), or surprisingly cool (such as our discovery of Scanifly), nothing was more anticipated than our chance to attend a talk presented by Enphase titled, “Design and Specification of Grid-Agnostic Enphase Ensemble™ based Systems."  (Enphase describes the Ensemble system as being “grid-agnostic” because it is intended to switch seamlessly between grid connected and grid isolated operation.) Here is our take…

The room for this talk, as was the case with a number of talks, was way too small for the number of interested participants.  I arrived early and was rewarded with a seat.  Late arrivals were SRO.  The talk was presented by Peter Lum, with an assist from Field Applications Engineer, Nathan Charles. 

Key Takeaways

For folks looking for just the highlights, here are some (in no particular order):

  1. Initial rollout of the IQ8 in the U.S. will be as part of the Encharge energy storage system
  2. Encharge will come in two basic flavors, a 3.3 kWh, 1.28 kW unit, and a 10 kWh, 3.8 kW - both with a peak surge output of 150% rated power for one second
  3. The 3.3 kWh unit will be 24″ high, 13″ wide, and 12″ deep, weighing 88 lbs, mountable either on the floor or the wall, and it can be mounted outdoors
  4. Cells are LFP, cooling is passive, and comms are - surprise - Zigbee
  5. The 3.3 kWh unit has four IQ8 microinverters inside, that are field replaceable should one fail
  6. The battery cells are not tied to any one microinverter; if a microinverter fails the storage capacity is unaffected, but peak output power is diminished
  7. Warranty will be for 4,000 cycles (100% DoD) or 10 years, whichever comes first
  8. For a microgrid to form, there must be roughly the same amount of IQ8 power as there is IQ6 or IQ7 power in the system
  9. Not compatible with M-series microinverters, “at launch”
  10. No word yet on pricing, anticipated deliveries to begin Q4

A Little More Depth

So those are some highlights, let’s talk about some details. The smarts inside the IQ8 is an Application Specific Integrated Circuit (ASIC) with some 5 million gates. As a result, the IQ8 is able to update its control vectors every 20 ns.  Thus, the individual IQ8 provides the primary control over the microgrid, and there is no master/slave relationship.  However, the IQ6 and IQ7 do not have that level of independent control functionality, and so they rely on secondary control, via the Envoy, to stay in sync with the microgrid.

As with its other IQ cousins, the IQ8 is a bi-directional inverter, meaning the same device that can be in an array, converting DC to AC, can be in the battery, converting AC to DC to charge the cells.

Keying off the 2017 NEC (which California will adopt come January), we were introduced to a new acronym: MID - which stands for Microgrid Interconnect Device, and is defined as, “A device that allows a microgrid system to separate from and reconnect to a primary power source.” (705.2)  The Enphase MID is referred to as Enpower, and it essentially has three components: an automatic transfer switch, a neutral forming transformer (recall that the IQ series just uses the two hots, L1 and L2, so the NFT is necessary to power 120 volt loads when off grid), and a control device.  Comms are - you guessed it - Zigbee.

Use Cases

There are two primary use cases for the new Encharge component, Energy Optimization, and Storage with Backup.  Let’s look at each one in turn.

Energy Optimization

Energy optimization, or more to the point, Time-of-Use arbitrage, involves storing energy during the peak production portion of the day (instead of exporting it to the grid) and using it later in the day for local consumption.  This becomes important as utilities - think SCE - switch to TOU rates where energy in the middle of the day is significantly cheaper than energy during the peak TOU period (more and more, something like 4-9 p.m.). 

Our friends over at Energy Toolbase just blogged about, “A Historic Moment for Residential Energy Storage Economics: California’s new Time-of-Use Rates,” noting that for the first time it was possible to model a more economically advantageous system adding storage, than just solar alone.  Which means that the Energy Optimization use case may pencil out on its own - though that is hard to say for sure until we have some actual pricing!

Enphase provided the following illustration (sorry for the lousy images, taken from the side with my phone!). You can click on the image to see a larger version.  

 energy optimization

On the far left is the Encharge 3.3 kWh storage system showing the four IQ8’s.  To the right is an array built on an equal number of IQ7 microinverters - but note well, this is not a microgrid configuration.  Why?   Because it doesn’t have a MID, and per the 2017 NEC, you can’t have a grid-agnostic microgrid without a MID. 

In the middle is the latest version of the IQ combiner box.  (We just installed one of these and frankly, I’m not a big fan.  The wiring for consumption CTs requires you to cross reference an unmarked connection block to the lid for the wiring diagram.  This is going to be error prone, IMHO.  Also the Envoy has been reduced to just a circuit board w/out its own case.  Ok, it’s in a NEMA 4 box so the case is probably not needed, but if you are trying to operate it with the deadfront off (say during testing), you need to watch where you put your fingers!  A false economy here, I’d say.)  

Note the green boxes which denote updated software both in the cloud and in the Envoy.  Also, the Envoy picks up a Zigbee device (to communicate with Encharge) to be attached to one of the two USB ports on the Envoy.  (As we noted before, Zigbee is built into Encharge, though not called out on this slide.

This is super easy to set up as the Encharge just lands on one of the breakers in the IQ combiner.  And while it may - assuming our friends at ET are correct - pencil out, it isn’t what all the buzz has been about, so let’s turn to that use case, shall we?

Storage with Backup

Ever since I made my pilgrimage to Petaluma last summer, the amazing microgrid has been the feature that everyone is eager to see.  The good news is, we are closer!  The bad news is, this isn’t going to be as easy as we had hoped.  So here is the key diagram from last week:
Encharge for backup

There is really only one change from the prior diagram and that is in the upper right hand corner, where the Enphase MID - dubbed the Enpower 200G, has been added.  The switch is rated at 200 A (that is the significance of the 200, G stands for grid), and in theory could be an all home setup.  In a grid outage, the Enpower ATF switches and the microgrid forms - automagically.  Depending on the actual array and storage configuration deployed, will determine how much of the house loads could actually be powered here. 

There is one fly in the ointment in this illustration.  In many parts of the country, the utility meter is mounted outdoors and the distribution panel - the Main Load Center in the slide - is located indoors.  In such a scenario, the Enpower MID could be wired in between those two components with minimal disruption or cost.

Alas, in California, at least in Southern California, that is not how we do things.  99.9% of the services that I have ever looked at consisted of a combination meter and load center “all-in-one".  The rub here is that there is no easy way to physically interconnect the Enpower device between the meter and the load center.  When pressed on that issue, Enphase - accurately, if not helpfully - pointed out that we would have the same problem with any such storage solution and the combo meter/load centers.  True enough, but we have been talking about this product for a long time now, and you would like to think that they would have a clean solution in mind as to how to make this work by now.

UPDATE: I spoke with Enphase Field Applications Engineer Nick Dadikozian about the following possible solution.  Assuming that the utility and the AHJ go along, you could add a separate meter socket and wire the line side to the service, with the load side of the socket connecting to the line side of the Enpower MID, and the load side of the MID to the load side of the meter socket in the combo panel, or if no way to do that, wire to the line side of the combo meter socket and install appropriately rated jumpers in lieu of the relocated meter. 

Of course, another approach is to have a critical loads subpanel, with a breaker on the main panel and the Enpower in between.  That, I suspect, will be the approach most commonly taken.

So there you have it – all that I could absorb from our relatively short session, and some follow-on conversations with Peter over the next couple of days.  (My thanks to him for his patience in dealing with my myriad questions.)

Eager to hear your thoughts on how you will be using this system.



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Comment from:
Thanks for posting Jim, a lot to digest here … will get back to you.
04/03/19 @ 22:23
Comment from:
Did Martin Fornage attend conference?
04/03/19 @ 22:59
Comment from: Jim Jenal - Founder & CEO
Yes he did, but not this session. Jim
04/03/19 @ 23:06
Comment from:
Thanks, Jim! Any word on generator interoperability?
04/04/19 @ 14:34
Comment from: Jim Jenal - Founder & CEO
@solarguy - It didn’t come up during the session that I attended (there were two), but I have been told previously that the Ensemble system is interoperable with a generator. Whether you can get the AHJ to agree or not, is another question!
04/04/19 @ 20:04
Comment from:
Automatic Generator “Offloading/Fuel Reduction” appears to be key goal/ROI Feature from comments in previous Seeking Alpha dialogs.
04/05/19 @ 15:59
Comment from:
5 stars
Hi Jim, This read just erased about half the anguish of missing last week’s conference. A few questions: 1. ATS/Meter intercept wiring challenge for combo meters: As desirable as a combo meter solution might seem, leaving pool pump/HVAC type loads on main distribution panel (i.e. off the PLP) could avert major headaches for smaller storage units (<10kWh) during outages, particularly if homeowner is unable to quickly or remotely deactivate heavier loads/thermostats (unnecessarily depleting storage capacity). There’s more than a niche market opportunity here for the Siemens/Square Ds of the world: Similar to how Siemens launched their 200A panel with 100A PV input to bypass the line side approach, making ‘interceptable’ meter to main breaker bussing / wiring would open up a market for quick/cheap ATS/whole house battery backup integrations. In the meantime, as you stated, the PLP -> MID / Enpower -> HOM2200 (or similar) breaker in main combo would seem to be the way to go. 2. Genset interoperability Assuming no clear guidelines have been presented on this, here’s a possible workaround - Wire genset controller (ex: Generac Nexus) to NC relay which opens (i.e. starts genset) when 12V signal is sent from standalone autostart unit when pre-set battery SOC reached and PV is below threshold (night-mode / thick cloud cover). Thanks again for the illuminating post!
04/05/19 @ 04:57
Comment from:

Interesting reddit video of IQ8 at work w/ post about potential collaboration between Zola & Enphase in subsaharan Africa:


“Enphase and Zola Electric are partnering to bring these to millions of homes in Sub-Saharan Africa this year”

04/05/19 @ 05:28
Comment from: Jim Jenal - Founder & CEO
I am pretty sure they are the special customer who paid Enphase $6 million to get to the head of the line with the off-grid IQ8.
04/05/19 @ 17:23
Comment from:
Jim, Thanks for the excellent Summary, Ponderings & Questions? 80% of 240V * 200A = 38kW. So with Line Side Interconnect and the right Combiners, the system PV Limit is 38kW with the 200G? Rating of the OCP of Low side of the Neutral Former? May not be of concern, since the Heavy Lifting should be Line to Line anyway. Will the System Zero Export on the Initial Release that will satisfy Utilities in non net meter States Like Alabama?
04/05/19 @ 15:53
Comment from: Jim Jenal - Founder & CEO

I have zero specs on the components of the MID, except that the switch is rated at 200A - which as you suggest is 160A continuous.

As of today’s IQ microinverters you can have them configured for non-export (for Hawaii, in particular) simply by selecting the utility profile when you commission the system. So I am (99%) certain that Ensemble will be able to satisfy that requirement on initial release.

04/05/19 @ 17:27
Comment from:
Thanks for keeping us updated Jim! I love the potential of IQ8 especially when coupled with storage. My interest is in both on and off grid versions. So many use cases…RV trailers, shed power for charging up the lawn mower, water pumping, greenhouse ventilation, its endless. The tech should also rock the battery charging world by making charge controllers redundant. Wonder if there is any benefit to wiring solar panels in parallel on the dc side similar to what they’re doing with Encharge batteries? If one micro failed your capacity factor would go up and only slightly reduce your overall output. Compared to a guaranteed loss of the one panel/micro output. There would still be no HVDC on the roof…and current is defined/controlled by the output of the micro… Again much thanks!
04/06/19 @ 18:13
Comment from:
@Jim Jenal What is your opinion for those interested in features of the Enphase Ensemble system, but want to install an Enphase IQ7 system now? Likely Ensemble/IQ8 will integrate easily with IQ7 roof array enabling continued operation (when sun out) during utility grid fail? Can this happen from a “black start” or would a battery be necessary?
05/07/19 @ 12:42
Comment from: Jim Jenal - Founder & CEO

Bill –

I think it makes sense for people to go ahead with an IQ7 install now, particularly given the two opportunity cost factors, namely: a) reducing high utility bills this summer, and b) taking advantage of the full 30% ITC (though the step-down to 26% does not make this too significant of a factor).

I’m not sure whether the system could switch over at night without a battery - not sure where the power to operate the ATS would come from. When the sun came up, the micros could form the grid, but I’m not sure how that is going to work from a regulatory perspective.

When we saw it in the lab last July, there was no battery connected (initially) and when they threw the breaker (simulating the grid failing) the IQ8 micros formed the grid in an imperceptible amount of time.

Best regards…

05/10/19 @ 00:55
Comment from:
5 stars
Am I missing something, or will the neutral forming transformer have to be a fairly large piece of equipment? If the MID will be 200A, then potentially the neutral will have to carry many kVA, no? This can’t be a cheap/small piece of equipment, can it?
05/20/19 @ 16:22
Comment from:
Just looking around at some 15kVA dry-type distribution transformers, and they are floor mount units starting at 170lbs. A 25kVA unit was 230+ lbs. I suppose in worst case scenario calculations, with one leg carrying the entire load (160A), the 25kVA unit would be about as large as you would need. But that’s a large piece of equipment that will need a home.
05/20/19 @ 16:41

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Jim Jenal is the Founder & CEO of Run on Sun, Pasadena's premier installer and integrator of top-of-the-line solar power installations.
Run on Sun also offers solar consulting services, working with consumers, utilities, and municipalities to help them make solar power affordable and reliable.

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