Thoughts on Solar

I just returned from two days of hands-on training with the new Ensemble Storage System from Enphase Energy at their HQ in Fremont, California.  Here’s my take…

Ok, to say that I have been somewhat obsessed over the Enphase IQ8 and its incarnation in the Ensemble Storage System over the last year and a half would be an understatement, having written about it here, here, here, here and here!  I’ve attended webinars and conference sessions where Ensemble was discussed and the technology explained.  But like any good installer, what I really wanted to do was get my hands on these devices, wire them up, and get a real feel for what it takes to put these on a client’s wall.  This week I got my chance!

Ensemble Family Photo: Enpower, Encharge 10, Encharge 3, IQ Envoy Combiner.
(Click for larger image.)

Here is one view from the lab at Fremont.  On the far left is a main service panel and meter. To its right is the Enpower Smart Switch which acts as a Microgrid Interconnect Device (or MID). Next is the Encharge 10, alongside its smaller sibling, the Encharge 3. 

Next is the IQ Envoy Combiner (not new, although it now comes with a cellular modem standard).

Finally, there is the simulated array made up of IQ6’s and IQ7’s (both regular and Plus versions).  Out of the field of the picture is a PV array simulator that powers the microinverters.

Oh, and no demo would be complete without some loads, including a light, a microwave, and an electric stove - all of which were powered by this system with the grid disconnected.  (Some people have asked how fast was the switchover - so fast that the light doesn’t blink and the clock on the microwave did not reset.)

Over the course of the two days we spent a lot of time in the classroom - headed by Peter Lum, trainer extaordinaire - focusing on the nitty gritty.  How do you size an Ensemble system, how do you mount these things, how do you wire them up, how do you comply with the electrical code?

Our lab time on the first day was a demo of the system on the wall.  The second day, we were actually mounting these to the wall and wiring them up.

Getting Our Hands Dirty

I’ve already written a lot about the specs of these devices, so I won’t repeat that here.  The point of this post is to discuss the actual installation process.

Enpower with deadfront removed alongside Encharge 10.
(Click for larger image.)

On the left is the Enpower with its deadfront removed, alongside the Encharge 10 with its cover removed.  (The whitle, L-shaped pieces on top of the Encharge 10 cover are the screw down covers for the Encharge’s wiring compartment.)

Encharge 10

Let’s start with the Encharge 10 - as the photo makes clear, Encharge 10 is actually three Encharge 3’s mounted on a common mounting bracket.  Each Encharge 3 includes four IQ8 microinverters, and they are individually replaceable, so should one ever fail, the others continue to operate and the monitoring will advise the installer of which unit has failed.  All the field technician needs to do is remove the cover, disconnect the failed microinverter, plug in the replacement, and put the cover back on. Moreover, because the micros are on a common bus inside the Encharge 3, if one should happen to fail, you still have 75% of your total power, but 100% of your stored energy!

An Encharge 10 constitutes a 20 Amp branch circuit, and up to two Encharge 10’s can be wired together in series (maximum wire size is #8).  If a larger storage system is required, then the Encharge units need to be landed in a dedicated subpanel.  (The Enpower is rated for up to 80 Amps of storage.)

To the left of the IQ8s is the battery management unit and the battery disconnect switch.  (Not really visible in this picture is a status LED that shows whether the battery is on or not, whether it is idle or charging, and the relative state of charge as it shifts from blue (discharged) to green (charged).

The finned area is the actual LFP batteries themselves.  All cooling is passive, no fans are involved.  The unit needs to be mounted a minimum of one foot from the ground, and if you have more than one row, at least six inches (vertically) between rows.

The mounting bracket is secured to the wall with sufficient hardware and into sufficient structure to support the total weight of 346 pounds.  (Enphase will be releasing a white paper on best mounting practices - a must read to be sure!)  Each individual Encharge 3 is then lifted onto the bracket.  Given that these are over 100 pounds, this is a two-person lift to be sure!  My colleague Greg and I struggled a bit with the lift, mostly because I wasn’t really pulling my weight - so to speak.  (My value add isn’t really in lift strength!)  But the younger guys that were in the training with us managed the task with ease - ah youth!

Encharge wiring compartment.
(Click for larger image.)

The Encharge 3’s are then daisy-chained together in a wiring compartment at the top of the units, as you can see in the picture on the left.  Each terminal block can hold two wires, one coming in, one going out.  The last unit just has the incoming connection and no other termination is required.

Note the black piece connecting to the two units.  That is a plastic, snap in conduit section that is added after the units are mounted.  The last unit in the chain has a rubber plug in that opening to keep the wiring compartment watertight. 

Once the wiring between the Encharge units is complete, the unit closest to the Enpower is then wired to it, and then the tops can be screwed on, and the cover added.

Enpower

Which brings us to the Enpower - which is both a MID and an interconnection center.  Note, however, that Enpower is not a general purpose panelboard, but rather, a specially listed UL device and as such, the 120% rule does not apply.  As a result, the Enpower will accommodate up to 80 Amps of PV input (i.e., a fully populated IQ Combiner) and 80 Amps of storage input (i.e., four Encharge 10’s.)

In the picture above, the input from the meter (if serving as a whole-home backup system) or the the main service panel (in a partial-home backup) comes in on the right hand side.  In the picture there is an Eaton main service, bolt-down breaker installed.  If this were intended for a partial-home backup with a breaker in the main service panel, the Eaton breaker could be omitted and the input conductors would land on the existing lugs.

Directly above that main breaker is the isolation relay, which trips when the grid fails and isolates the system for creating a microgrid.  Above and to the center is the neutral forming transformer that allows the system to power 120 VAC loads.  Below that on the left is the common bus that holds (going counterclockwise from the top left) the breaker for the PV, the breaker for Encharge, a breaker for a generator (but not yet), and the breaker for the neutral forming transformer.  

You can see the conductors for all of those connections pre-wired in the photo, waiting to be attached to the appropriately sized breaker.  The actual connections for both the PV and Encharge are made on lugs at the very bottom.

The output to the loads is at the base of the common bus where an appropriate Eaton breaker is added.  Fun fact - the Eaton service rated breakers actually swap L1 and L2 from one side of the breaker to the other!  This means that installers need to pay attention to their phasing so that the consumption and production CTs are reading the proper values - a topic we discussed in some detail in the classroom, and then verified in the lab - damn, isn’t hands-on training the best!

The Enpower switch, the Encharge units, and the IQ Envoy Combiner all communicate directly via Zigbee.  In fact, each unit has two radios, one at 2.4 GHz and the other at 900 MHz and the units switch automatically between channels and frequencies as necessary to provide the clearest signal.  Moreover, if the Combiner box is remote from the Enpower but closer to Encharge, the Encharge unit (or vice versa) can serve as a repeater to get signals to the other devices.  Pretty clever.

Providing Feedback…

Of course, there are two purposes to a training like this during a beta period: to get the initial installers up to speed with the product, and for the installers to provide Enphase with feedback.  Along the way we discovered a diagram that was wrong (nice pickup, Greg!), and a couple of places where esthetics got in the way of utility.  Those are easy things to correct, and Enphase’s CEO himself came into our classroom to hear our feedback directly!  That is a level of dedication to hearing what the long tail has to say that just isn’t happening with other solar companies.

Finally, a point of personal privilege: some years ago we did a video about our installation at Westridge School for Girls here in Pasadena (you can find it here.)  Well what do you know but that video is part of a loop that is playing in the Enphase lobby!  One of the engineers actually came up to me and exclaimed, “You’re the guy in the video!"  Fun way to end our two days at Enphase HQ. 

Bring on the Beta!