Thoughts on Solar

They say all good things come to they who wait - and boy have I been waiting for this day for a long, long time! But Enphase has finally released their much anticipated IQ8 microinverter - the first device that can provide “Sunlight Backup” without batteries! Here’s my take…

Long Time Comin!

Those of you who follow this blog know that I have been writing about the IQ8 microinverter for almost forever, starting with this piece from August 2018, titled “What I saw at Enphase - Mind Blown!“  Back then I was fortunate enough to get to visit the Enphase lab in Petaluma and got to see a demonstration of what Enphase is now calling “Sunlight Backup” - the ability for your PV system to continue to operate when the grid goes down.  While I wasn’t allowed to record the demo, Enphase, to mark the public release of the IQ8, has posted the following video which illustrates the concept quite nicely:

This is the wow-factor for the IQ8 - when combined with an automatic transfer switch for code compliance - if the grid fails during the day, your PV system with IQ8s on the roof will continue to produce power, no batteries needed!

Of course, there are a few caveats: during the day the output from your PV system will fluctuate based on prevailing conditions.  For example, it rained like crazy here yesterday - and the power went out!  How much value would the PV have been then?  Not too much.  However, today the sun is shining like crazy and the weather is cool, the air clean - outstanding day for solar production.  Go ahead, take down the grid, we’ll be just fine!

And a word about code compliance.  The anti-islanding rules that require a grid-tied PV system to not export power to the grid when the grid fails, are still very much in force.  After all, we want our systems to be safe for all involved.  So to meet code, you need to also install an automatic transfer switch, which Enphase is now calling the IQ System Controller - FKA Enpower - into your system.  But the IQ System Controller costs a fraction of what the actual storage components do, so this is a way to have some power during the day at minimal additional cost!

As this video nicely demonstrates, if you have too many loads turned on when the grid fails, the microgrid cannot start.  But as soon as you shed sufficient loads, the microgrid will form instantly, all on its own.

Enphase has put together a pretty good chart (albeit kinda small here, but click on it to see it full size) that shows the components needed to achieve different capabilities:

Solar Only is what we have been doing for years.  Home Essentials Backup, aka partial-home backup, and Full Energy Independence, aka full-home backup are what you get when you add storage.  But Sunlight Backup is what IQ8 brings to the party!

Please don’t keep-a me waitin…

So when can we put these on your roof?  Well not today, that’s for certain.  We are being told that we will see shipments toward the end of December.  (Of course, if they are coming into the ports of either LA or Long Beach, we could be waiting for months!)   First quarter of next year is likely a safer bet.  Still waiting to see firm pricing as well, but figure something like 25% higher than the comparable IQ7+ that we have been installing for the past two years - and without a single unit failure!

The wait is almost over - watch this space!

[Editor’s Note: Today is Veterans’ Day, so a shoutout to our Vets: Victoria and Greg,
and to all the Vets out there - thank you for your service to our country.]

The Enphase Ensemble system is almost here, so let’s start talking about how this is going to work for existing and potential clients.

What is Ensemble?

Ensemble is the name of the new Enphase storage and control system.  It consists of the Enpower smart switch, some amount of Encharge battery systems (depending on your needs),  and an IQ Envoy to handle communications.  The system is capable of supporting “whole home” backup, although for most clients a “partial home” system will make more sense.

Enpower Smart Switch 19.7″ x 36″ x 9.7″ 80 lbs.		Encharge 10 kWh Storage System 42.12″ x 26.14″ x 12.56″ 346 lbs.

The Enpower smart switch contains an automatic transfer switch - or a Microgrid Interconnect Device, to use the language of the NEC (to isolate from the grid when there is a grid failure) - rated at 200 amps, and a neutral forming transformer to allow for 120/240 VAC operation.

The Encharge batteries come in two sizes: a 3.3 kWh battery and a 10 kWh battery (which is actually three of the 3.3 kWh batteries mounted behind a common cover).  Inside the 3.3 kWh unit are four IQ8 microinverters, and thus 12 as part of the 10 kWh unit.  The 10 kWh unit, which is going to be the minimum size that you will want, has a continuous output power of 3.84 kW, with a peak out of 5.7 kW for ten seconds - enough to allow for inrush current from motors, for example.

Both units have a NEMA 3R rating so they can be installed outdoors (though you will want them out of direct sunlight if possible), and come with a 10-year warranty.

How Will it Fit with My Existing System?

First, you need to have IQ microinverters.  At least as of the initial rollout of this system, the older microinverters are not supported.  That means that the M and S-series of microinverters have to be replaced to IQ-series microinverters to work with Ensemble.  (I do not know if this will change in the future, but it is the guidance that we are getting at this time.)  It is possible that there will be some sort of replacement program (like Enphase did with the legacy M-190 customers), but I have not gotten any word about such a plan yet.

Second, you need a rough parity between the output power of the solar array and the output power of the Encharge batteries.  That means that if you have a single, 10 kWh Encharge battery system, the rated output power of the installed microinverters on the roof, has to be at or below 5.7 kW.  Here’s what that means for the IQ microinverters that have been installed in the past three years:

As the systems that we have been installing have all been IQ6+ or IQ7+, you can see that with a 10 kWh Encharge system, you are limited to 19 panels - a 6.365 kW system when paired with LG 335’s.

How can I Plan to Make Ensemble Work Best for Me?

Making this work requires some planning and modifications, and not every existing system will be a good candidate for this.  As we have noted in earlier posts about Ensemble, most folks in Southern California have what is called a combination service panel where the meter unit and the distribution unit (where the breakers are) are in the same, physical device.  Without replacing the service panel, you are left with a configuration that will looks something like this:

 

Ensemble Wiring Layout - click for larger.

That is your PV system in the top left powered by IQ microinverters.  Those land on an IQ Combiner (which Run on Sun has been using since the IQ microinverters were rolled out).  On the far right is the grid, feeding your meter and the service panel.  (In an existing system, the output from the IQ Combiner goes to a disconnect switch and then to a breaker (or a lug) in the service panel.)

To add Ensemble, you need to connect the Enpower switch to the service panel via an appropriately sized breaker.  You also need to create an emergency load subpanel, with the critical loads that you want to operate during an emergency.  (This takes a good deal of thought - you will need to know the power requirements of the devices you are looking to operate during the outage and size the system accordingly.)  Everything then flows through the Enpower switch (including the possibility of a backup generator, though that will not be immediately supported).

We do not yet know what the utilities or local AHJs will say about this.  Presumably the utilities still want a lockable disconnect switch on the output from the Combiner, but will they also want one on the output of the Encharge battery system? The Encharge system allows for two, 10 kWh units to be “daisy-chained” together; for larger storage system a storage subpanel is required.  Also required is consumption monitoring, which may not be possible on some service panels (due to space constraints) without rewiring the entire panel - ugh.

So… this is going to be a great product, but it is neither a cheap nor simple process.  Interested?  Let’s get started!

Fire damage at a Walmart store.

We recently wrote about a spate of fires that occurred at Walmart stores due to problems with solar power systems on their roofs.  The damage, in some cases, was extensive and overall, painted a pretty bleak picture of commercial solar.  But it doesn’t have to be that way - read on to learn about the solar fire that wasn’t!

One of the problems with the systems that were installed at Walmart is that they were tied to string inverters.  That means that multiple solar panels are wired together into a series string.  When solar panels are wired together that way, the voltage in that string adds with each additional panel.  So if you have twenty panels wired together, and each panel produces 40 volts, the total voltage for the string is 800 volts!  (Indeed, commercial systems can be as high as 1000 volts!)  If there is a gap - say from a loose wire, or a damaged panel - you can get an electric arc that can easily start a fire.

Yikes!

But the other day we were doing a maintenance check on a small commercial system that we installed a few years ago.  While we were installing a software update we did a visual inspection of the array and came across this - a totally shattered panel!

Totally shattered panel - but no fire here!

So what happened here?  Turns out that the company that owns the system had a mishap, and a brass valve fell on the panel from about 100′ in the air - yep, that will do it!

But more importantly was what didn’t happen - there was no fire.  This was during the middle of the day, and the system was operating at full capacity, yet despite being entirely shattered by the blow, there was no fire because this was not part of a high voltage string.  Rather, this was part of an Enphase microinverter system, so the total DC voltage was only 40 volts.  At that low a voltage there is no arc, and with no arc, there is no fire!

We have heard people say that string inverters are the way to go with commercial systems because they are so much cheaper.  To which we reply - really?  How much does it cost to repair the damage from a fire like those that Walmart has experienced?  Moreover, with a string inverter system, finding faults before they become a hazard is much harder than it is with an Enphase microinverter system.  The Enphase monitoring tells you where the problem is so you can fix it with minimal impact on your operations.

Bottom line: beware of false economies.  Spending a little more to have a safer system is just smart business.  That’s one of the many reasons that we are exclusively an Enphase shop - simply safer solar!

On August 20th, Walmart sued Tesla Inc, alleging “widespread negligence” in the installation and maintenance of systems on something like 240 Walmart stores across the country, resulting in 7 fires!  Is this a uniquely SolarCity/Tesla problem?  Are rooftop solar installations invariably unsafe?  Or is there a design difference that can make systems safer, particularly for residential solar clients?  Here’s our take…

Fire damage at Walmart store allegedly caused by Tesla solar installation.

The 114-page complaint is a pretty damning set of accusations, saying that the installations were rushed, that faulty materials were used during the installation, and that the maintenance provided by Tesla did not meet “Prudent Industry Practices."  For example, after one Tesla maintenance team left a Walmart site, a DC combiner box, which could involve DC voltages of as much as 1,000 volts, was found left with the cover off!

Other problems involved multiple solar modules with “hot spots” possibly caused by micro-fractures of the cells, as well as mismatching cabling connectors (connecting MC4 connectors to Amphenol connectors) such that excessive resistance in the connections could occur, resulting in overheating, and potentially fires.

While the lawsuit is specific to SolarCity, and its now parent, Tesla, the types of conditions described are going to be potentially present in any string inverter system - which all of these were.  Since you are dealing with strings of solar panels, you are dealing with higher string operating voltages, with more power running through those strings.  If you use mismatched connectors, or stand on solar modules (one of the best pictures in the complaint shows the foot of a Tesla maintenance inspector standing on a solar module!) you can have the potential for fires.

A Safer Way…

DC arc at 240 volts.
Video by John Ward
6:20 into the video.

Which leads us to yet another reason to prefer the Enphase microinverter approach - no high DC voltages involved!  When a DC circuit opens under load, it is possible to get significant arcing, like you see at the left - ouch! 

But since each solar module plugs directly into the Enphase microinverter, there is no additive effect leading to those crazy high DC voltages.  Open a DC circuit with a voltage of 40 volts or so and guess what? No arcing!

While human error is never going to be eliminated in the solar industry – those are human beings doing the work after all – the Enphase microinverter system is inherently safer.  And if you are going to put solar on your home, school or business, isn’t safer what you want?

On the heels of their video release last month, the folks at Enphase have now published an FAQ page on the entire Ensemble system.  Here are some highlights…

Perhaps the most exciting item is that they are expecting deliveries around Christmas time – what a great gift!  That said, I’m sure quantities are going to be limited at least initially. To that point, however, it looks like there will be a “pre-order” option - though the FAQ page is silent on details or pricing.

The most disappointing answer is that the system will not be compatible with S and M series microinverters, although they are planning an upgrade path, similar to the “Early Adopters” program that they had earlier this year.

Happy to hear your feedback - obviously we are following developments here closely, watch this space.