Thoughts on Solar

For a long time the solar industry - particularly the residential solar industry - has portrayed our systems as “maintenance free".  “Clean the panels when they get dirty, but otherwise you are good to go,” is a common conversation between an installer and their client.  And certainly given the ever-improving warranties being offered by top-line manufacturers, that claim didn’t seem so far-fetched.  But lately I’ve seen some things that have caused me to rethink that whole conception of maintenance-free solar systems.  Here’s my take…

Old Thinking…

My old thinking - that these systems really did not require maintenance over a 20-year lifetime - was predicated on more than wishful thinking.  After all, we used only the very best components: LG solar panels, Enphase microinverters, racking from Everest and Unirac, Polaris connectors instead of wire nuts, etc.  We built our systems with care, using well-trained people, including those who were NABCEP certified, and we went above and beyond all code requirements.

What I have discovered recently, in servicing a couple of older systems, is that it isn’t the components people worry about failing like the panels or the microinverters, that cause the problems.  We have never had an LG panel fail, and since Enphase moved to the IQ series of microinverters we have had exactly one microinverter fail - one!

No, that has not been the problem, it is the little stuff that is taking systems down.

What I’ve Seen…

Before I can talk about how things have failed, let me show you how things start out.

On the right you see a rail-mounted junction box on the roof.  In here we connect the Enphase IQ-cabling from the microinverters to THHN-2 wire for the run from the roof to the building-mounted combiner box.  (If you look to the right, your can see black marks on the racking bolts - we mark them with a sharpie after they have been torqued.)  We have a grounding bushing on the incoming conduit, and all of the connections are made with Polaris connectors instead of outdoor-rated wire nuts.  Why the Polaris?  Because you can do a pull test on your connection: when the wires are screwed in you can pull on them to make certain that they are secure, something you simply cannot do with a wire nut.

Put simply, it is the best connection method of which I’m aware and so that is why we use them, even though they cost 50 times as much as that wire nut.  But here’s the thing - they aren’t foolproof either.

We got an email from the Enphase Enlighten monitoring system alerting us to a client whose system had gone offline.  That system had a fused disconnect and I fully expected to find a blown fuse.  Nope fuses were fine, and the breaker hadn’t tripped either.  Time to go on the roof and check out the junction box - and here’s what I found…

What on earth?  The Polaris in the foreground has failed completely, but why?  The Polaris behind it looks like the day it was installed, so why did the other one literally melt away?  Mind you, this wasn’t a case of something shorting out - neither the fuses nor the breaker tripped.  There are two wires being joined there, a 12 gauge from the Enphase cable and a 10 gauge for the run off the roof.  The #10 is still securely held in what is left of the Polaris, but the #12 has broke off - which is why the system had failed.  But why?

My best answer - speculative of course because I didn’t see it happen - is that perhaps the #12 was not as securely under the screw as it should have been, and over the course of the nine years that it was in service, with the daily heating and cooling, it continued to loosen, until the resistance of the connection increased, causing it to heat, melting insulation on the wires and on the Polaris, until the wire broke.

What could have prevented this failure?  Well, as mentioned, this system performed just fine for nine years before failing.  What if those connections had been checked around Year 5?  If, as I surmise, the connection was loosening, an inspection might have caught that and a simple re-tightening would have cured the problem before the failure could occur.

Now this is only one failure out of a multitude of systems using the same components, so it is fair to say that this is low-probability event.  But we have seen other, similar issues including a performance meter that failed, and a line-side tap that loosened, over heated, and failed.

The bottom line is that we are re-thinking how we approach maintenance for resi solar.  I would be interested to hear other folks thoughts about this, so please leave us a comment and tell us about your experiences.  Hopefully we can all learn something about how to make our systems better, if not, “maintenance free.”

I suspect that most of my NABCEP-Certified colleagues have had this happen - you are on your way to a jobsite when you pass a solar installation that is so painfully bad, that it stops you in your tracks and you just have to go and take a closer look at what happens when Shortcut Solar has botched another job. Follow me into a realm where you never want to find yourself, the horrifying reality of Shortcut Solar at work!

I brake for Shortcut Solar!

Wow, there’s a lot going on there and none of it good.  The panels on the left are facing a variety of trees.  The panels on the right have a significant pitch-up to the south, with a lot of exposure to the wind out of the north.  The cable management there appears to be: let it just hang down.  That middle section is supposed to have 18″ of clearance at the hip given the panels on the adjacent face, but they are actually overlapping the hip!  And how exactly are these attached to the roof?  A closer investigation was in order!

How not to do cable management!

Seriously? Looks like old Shortcut was in a real hurry the day they did this job!  There is a rail there on the high end - surely you could have found some way to use that to get those cables in order - but clearly that wasn’t a priority!

But it was this last image that really got me going.  Checkout this attachment scheme:

I apologize that the image isn’t too clear, but let’s try and break down what is going on here.  At the base in the foreground you can see what appears to be a 3″ or so piece of unistrut that has been cut to length and painted black.  There is no flashing of any sort visible here.  Instead, the strut has apparently been bolted directly onto the roof.  Perhaps those clever fellows from Shortcut Solar drilled pilot holes and squirted in some sealant?  Or maybe not - I mean why go to all that extra effort?

So that’s your attachment, now for the standoff - I know, how about a threaded piece of 3/8″ steel?  You can attach it at the bottom with a channel nut, and then just drill a hole in your aluminum rail and secure it with a nut above and below!  What could possibly go wrong?

Well let’s start with the wind.  When the Santa Ana winds blow out of the North, they will rock those panels, and that long, skinny bolt will flex with the wind.  It is steel and the rail is aluminum, which means that the steel, over time, will chew into the aluminum.  Enough flex over enough time, and that attachment scheme is going to fail - potentially in a catastrophic manner.

(Wanna see what happens when steel defeats aluminum on a roof in the wind?  Check this out!)

 It should come as no surprise that there is a better way to do this!  Here’s our preferred approach:

The picture on the right shows one of the strongest possible combination of solar attachment components you could ask for.  The rail and L-foot comes from Everest.  The 3-inch standoff is from Unirac and the flashing is from Oatey.

Under the flashing is a rounded-rectangular base plate that accepts two, 5/16″ x 3 1/2″ lag bolts.  Two lag bolts gives you twice the strength, and hedges against hitting just the side of a rafter, or a possibly rotted/weak spot.  The 3-inch standoff screws down onto the base, and the Oatey flashing goes over it all, insuring that it will not leak.  The L-foot is bolted to the standoff and is in turn bolted into the rail - which was engineered to accept this configuration.  All components are torqued to the manufacturer’s specification, and marked to indicate that the torquing was performed.

Does it take longer to do things that way?  To be sure.  Does that mean it costs more to do it this way?  Of course.  But ask yourself, which of these approaches would you want on your roof?

We take pride in doing things the right way for our clients so that they can sleep well at night, no matter how hard the wind blows!

And we will continue to brake for Shortcut Solar and call out his subpar work whenever we see it so that you, a solar homeowner, will know what to look out for when you choose a solar installer!

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?

Due to a misreading of the electrical code, many jurisdictions in the Run on Sun service area - and yeah, we are talking about you, LA County - balked at allowing homeowners to install solar if they were connecting to a center-fed panel.  This has resulted in costly, and unnecessary service panel upgrades, and even prevented some homeowners from adding solar at all!

Well good news - LA County has finally gotten with the program and agreed to interpret the code consistent with the intent of the code’s authors.  Here’s the scoop….

We have written about this problem at some length before - you can see those articles about solar and center-fed panels here.  The confusion arose because the code calls for connecting the solar breaker to the opposite side of the bus from the main breaker.  Since on a center-fed panel the main breaker is in the middle of the bus, there was no “opposite side” to mount the solar breaker, according to that tortured interpretation.  (In the photo on the right, you can see the large, main breaker in the center, with load breakers above and below it.)

To get around this problem in jurisdictions that held to that view of the code’s intent, various approaches were brought forward, all of them more dangerous and/or complicated than simply putting a solar breaker at one end of the bus.  For example, a couple of years ago, San Diego Gas & Electric introduced an adapter ring to fit between the meter socket and the service meter.   Soon thereafter, SCE adopted a similar solution, and that became our “go-to approach” for center-fed panels in LA County.

While County would sign-off on the SCE ring (or Generation Meter Adapter, as SCE called it), it was really an awful solution to the problem  For one thing, SCE charged the homeowner just under $500 for the install, and their technician had to do the work in full arc-flash protection gear - a testament to the hazard involved.  Beyond that temporary risk, the connection now left a pair of terminals in the solar disconnect with no over-current protection between them and the power pole transformer.  Short that connection out, and nothing would stop that current from flowing until the wires melted!

A better solution was recently brought to market in the form of the B3-Bypass breaker which we wrote about last Fall.  The B3 fits into center-fed panels and provides a much safer way to interconnect solar than the GMA ring.  But guess what?  Despite it having passed UL certification, LA County will not accept it, as we learned when we attempted to submit plans calling for the installation of the B3!

So, back to square one?  Well not quite.  While on the phone with County’s plan checker, I remembered that a code amendment had been passed effective a year ago January, that clarified the intent of the code when it comes to center-fed panels.  We had cited this amendment to county last year, only to be told that County had not yet approved the amendment - hence we installed multiple GMA rings with center-fed panels last year.

Here’s the language of the amendment:

A connection at either end, but not both ends, of a center-fed panelboard in dwellings shall be permitted where the sum of 125 percent of the power source(s) output circuit current and the rating of the overcurrent device protecting the busbar does not exceed 120 percent of the current rating of the busbar.

This is what we had been saying all along, and the code amendment makes it clear that this is an acceptable thing to do - as well as being cheaper and safer than any of the alternatives.

So, I asked the plan checker, had County gotten any closer to adopting this amendment?  “Oh,” said the plan checker, “we’ve been accepting it since January, 2017!”

Sigh.  So not true.  At least none of the plan checkers that we encountered in 2017 were accepting the amendment.  And for that matter, this plan checker did not volunteer the information.  Instead, he was about to sign-off on the GMA ring without ever bothering to mention that there was a safer and cheaper way for us to meet the needs of our client!  Is it too much to ask that a plan checker point out policy changes of which s/he is aware when discussing plans with a contractor?

Here’s the bottom line:  If your solar project meets the interconnection requirements set forth in the quoted language above, you do not need to upgrade your panel, and you don’t need a GMA ring to attach solar to your center-fed panel in LA County territory.  (And if it satisfies LA County, presumably every other jurisdiction should go along as well.)

If you need documentation - either as a homeowner to provide to your solar contractor who is trying to sell you an unwanted service panel upgrade - or as a solar contractor trying to convince a recalcitrant AHJ - here’s the link to the California Building Standards Bulletin that approves the amendment, and here is Bill Brooks’ write-up explaining the need and justification for the amendment. 
Here’s the money quote from the latter:

The fact that several thousand center-fed panels in good repair have required replacement over the past two years when, in fact these upgrades are unnecessary, presents a real and unnecessary hazard to the field workers required to perform these replacements. Any time a service equipment replacement is performed on a dwelling, utility service must be interrupted and significant electrical work must be performed to replace the equipment. This exposes the electrical worker to hazards of potentially live conductors and inadvertent errors that could even be fatal. The hazards of these upgrades is appropriate when the existing service equipment is damaged or has outlived its useful safe operating life. Performing these upgrades on perfectly good equipment that is not a safety hazard to the dwelling is an unnecessary risk.

We couldn’t agree more!