In Blog, Inverters, Micro Inverters & Optimisers

 

Enphase Comparison TestEnphase Microinverters are hands down, the best Microinverters on the market. But is a Microinverter the right option for your home? This Enphase review will first point out the advantages of using Enphase Microinverters: reliability, shading, flexibility, safety, and individual panel monitoring.

Next, we’ll look at the potential negatives of Enphase. I’ll discuss the obvious issue of having power electronics behind every panel, voltage rise, battery compatibility, and monitoring issues. I explain why I recently complained to Enphase about their attitude towards monitoring warranty, and I share their written response.

Finally, I eat humble pie while I discuss the findings of my side by side comparison of Enphase IQ7 and IQ7+ microinverters on 330W panels.

 

The Pros of Enphase Micro-inverters

1. Reliability in comparison

In the last five years, we have installed about 1550 micros on 77 homes. Most of these systems are over four years old, so they are close to halfway through their ten year warranty period. To date, we’ve had only four microinverter failures (0.25%) and a few communication issues that I’ll address later.

You could say that 4 out of 77 jobs means about 5% of our Enphase jobs have had a failure. That’s bad compared to a quality string inverter like Fronius. However, that’s not a fair comparison. Enphase’s “decentralised power topology” ensures that if one microinverter fails, you’ll only lose the production of one panel. When a string inverter (like Fronius or SMA) fail, you lose the production of the whole system.

SolarEdge is a fairer comparison. SolarEdge uses both rooftop power electronics (optimisers) and a central point of failure (the SolarEdge Inverter). How does SolarEdge fair for reliability? 34% of our SolarEdge jobs have had at least one fault. 11% of our SolarEdge inverters have failed so far, taking the whole system down. See my SolarEdge Stats here.

At 5% of our Enphase installs with an issue, Enphase in comparison is looking pretty damn good. (Remember it’s only 0.25% of Enphase microinverters that have failed.)

I went to the broader industry to ask for help. “Solar Cutters” is a community of solar industry experts with a diverse range of experience and opinions. I posed the question:

“Enphase Microinverters are ridiculously reliable: True or False?”

The jury is in. The Solar Cutter community agrees that Enphase is certifiably reliable.

Enphase’s “decentralised power topology”, coupled with its reliability, makes Enphase stand out from any other inverter solution on the market. But inverter reliability is only one part of the equation.

 

 

2. Heavy shading

enphase for heavy shadingEnphase microinverters are hands down the best solar inverter solution if your shading is extreme. This is because Enphase microinverters work independently of each other. If you have heavy shading and at some times during the day, just one or two panels are in the sun, those microinverters will produce power.

SolarEdge, in comparison, has to have a minimum of 6 panels in the sun to prevent production loss through voltage blocking. This is explained in-depth in my SolarEdge review.

Tigo and Huawei are also good options for shade. They do however require around three or four panels in the sun to get to the minimum operating voltage of the inverter. Read more on my Tigo review and my Huawei inverter Review. However, if shading is minimal, I prefer to use a couple of Tigo optimisers. As I explain later, the fewer Power Electronics on your roof, the better.

 

3. Townhouses and units

Enphase microinverters are often the best solar inverter solution for townhouses and units situations.

  • They are cost-effective for smaller systems.
  • Because they work independently of each other, they work well on small – multi-oriented roofs.
  • You only have an indiscreet box to install on a communal wall or in your unit, keeping that whinging chairman of the body corporate happy.
  • Because we run AC cable from the roof, the cable run can usually be more discreet and snuck inside wall cavities. You are welcome, Mr Chairman.

 

4. Safety

String inverters like Fronius and SMA require DC cable to run from the roof to the inverter. Solar DC power is theoretically dangerous if it’s accidentally damaged. (However Australian solar installation regulations are so strict. Solar DC cable installed to today’s standards are as safe as any other electrical wiring in your home.)

Enphase microinverters, however, reduce that risk even further. Microinverters eliminate the higher DC voltages by changing each solar panel’s extra low voltage DC power into AC power at the panel level. AC power does not have nearly the same potential for arcing as DC power.

In case of a house fire, Enphase will always be safer. Let’s say you chose a string inverter. When you turn off the main switch of your house off, the DC cable from your inverter to your solar panels will still be live. That’s unwanted fuel in a house fire.

If you had chosen an Enphase System instead, when you turn off the power to your home, the cable from your switchboard to your microinverters on the roof will also turn off. Safe as house fires houses.

 

5. Individual panel monitoring

Data geeks love Enphase. Enphase can monitor the production of every panel individually. But let’s see how valuable panel monitoring is.

  • Shading
    If trees are growing excessively, it could be a good indication of when to cut them back.
  • Blown bypass diodes
    Every solar panel has three bypass diodes to protect them from the shade. If they activate too often because of severe shade, then they may fail, and you will lose 1/3 of the production of your panel. We have only ever picked up six blown bypass diodes from the 5000+ panels that we have installed with individual panel monitoring (Enphase, SolarEdge or Tigo). However we’ve had four Enphase microinverters, and 56 SolarEdge optimisers fail.
  • Underperformance from panel degradation
    While good in theory, proving that your panel has degraded by 5 per cent more than it should have is very difficult even with individual panel monitoring. That’s why it’s essential to purchase a quality panel in the first place.

Installing expensive and complicated power electonics on the roof primarily to monitor the reliability of simple and affordable technology is madness.

 

 

The cons of Enphase microinverters

 

1. Multiple failure points

It’s unrealistic to put power electronics behind every panel on a hot roof and expect nothing ever to go wrong. When microinverters start to fail, the effort to replace one is much more than replacing a string inverter next to your switchboard. In the last five years, we’ve only had four micro failures. We replaced those microinverters under the ten-year warranty. But, if we get back onto your roof after the warranty period, you start paying. It is likely to be extremely difficult to remove the specialised nuts, bolts, and clamps that hold your panels on your roof.

Let’s hope it’s easy to identify and access the faulty micro. Ladder up, harness on. Panel clamps may be seized depending on your rail quality and installer’s finesse. Angle grinders come out. Replacement clamps are impossible to find ten years down the track. Should we open a can of worms and start replacing your rail?
Swapping out a string inverter in your garage would have been much more straightforward.

The end customer can purchase an extended warranty online after install. However, the extended warranty does not include the cost of labour of fault-finding, removing, transporting or reinstalling the faulty micro.

 

Here’s how an extended warranty compares to purchasing a product outright.

Enphase productCostWarranty covers shipping and labour?
Enphase IQ7+ Microinverter. Comes with 10 year limited warranty.Approx. $200 retailYes in practice, but no - according to limited warranty document.
Extend to a 15 year warranty$8.13 per microNo
Extend to a 20 year warranty$18.82 per microNo
Extend to a 25 year warranty$34.25 per microNo
1 phase Envoy & Ct's (for full monitoring) comes with 5 year warrantyApprox $650 retail.Yes in practice, but no - according to limited warranty document.

Because future maintenance will become problematic and costly, we generally only recommend Enphase (or any rooftop power electronics) where shaded situations and complicated roofs necessitate.

Oh, and in case you missed it: the components that monitor production and reveal any problems you may have with your microinverters over the next 10 years … those parts are only warranted for 5 years.

 

 

2. Battery compatibility

First, let me say that residential solar batteries are often unreliable and a bad financial decision. If you need proof of this claim, read this July 2019  Battery-Testing-Report from the Canberra Institute of technology.

BLOG: AC coupled vs DC couple coming soon

When batteries do become financially viable, Enphase will limit your options to an AC coupled battery solution. The main problem with AC coupling is a regulation problem. In Qld, ACT, parts of NSW and parts of Victoria, we are limited to a maximum of 10kW of inverters on each phase. And the 10 kW limit includes the sum of all the microinverters and the AC coupled inverter/battery charger.

Effectively this means you can have a large solar system and a small battery, or a small solar system and a big battery. If you had the option to DC couple, you could have a large solar system and a big battery. But going Enpahse does not give you that option. (This part became all too complicated for a single blog, Subscribe to my blog and I’ll send you my AC vs DC couple blog soon.)

 

3. Voltage rise

solar-voltage-rise-5Voltage rise is sometimes a significant electricity grid issue that can make your solar system turn off in the middle of the day. It’s a fairly complex issue explained in detail in this post. If you have potential voltage rise issues, we’ll need to minimise voltage rise. We’ll do this by reducing the length of the AC cable run, and increasing the size of the AC cable.

If you install a string inverter like Fronius, this is simple. We install your inverter next to the switchboard and use 10mm cables. In this situation, we might only contribute 0.2% to voltage rise.

If, however, you choose Enphase, we’ll need to run longer AC cables to your roof, and run small Enphase AC cables to every panel.  On a high set complex roof, it may not be feasible to minimise the voltage rise on an Enphase AC cable below 1%.

Not every Enphase system will have a voltage rise problem, but it’s a problem worth considering.

 

 

4. Enphase’s Achilles heel

A sign of a good company is how they respond when things go wrong.

Enphase monitoring issues

Enphase monitoring uses power line communication. The microinverter monitoring is transmitted over the same 240-volt cable that powers your appliances. Powerline communication works perfectly well – until it doesn’t. Noise or electrical disturbances from your household appliances can interfere with this signal, and the monitoring stops working. Which appliances can interfere with your monitoring? The Enphase-noise-troubleshooting guide gives a comprehensive list:

Light switches, dimmers, irons, microwaves, touch lamps, computers, battery chargers, phone chargers, laptops, compact fluoros, battery backup systems, hot water diverters, export limit devices or automatic controllers, switches, power strips, surge diverters, ethernet bridges, heavy motors, water pumps, fridges, power tools and kitchen appliances.

Just about every appliance you own could interfere with Enphase microinverter monitoring. Importantly Enphase is not claiming the offending noises are outside of the relevant Australian Standard on Electromagnetic Compatability (AS: CISPR 14.1:2018). It’s just normal electrical noise that happens from everyday appliances that are screwing up Enphase communications. The problem is an Enphase problem.

As it turns out, the first time we encountered this problem on one of our installs, I was writing this blog. The timing was joyfully serendipitous. Shane, my service manager, was all over it.

“Mark, Enphase has told us we need to buy a specific filter and install it at the customer’s premises in order to fix the noise issue.” Shane told me.

“That’s fine” I replied, “As long as Enphase reimburses us for the parts and labour, it doesn’t bother me”.

“That’s the problem” Shane continued. “Enphase Tech support is telling me they don’t reimburse anything for noise issues.”

I laughed out loud. Enphase wouldn’t be so stupid, would they?

 

Enphase mans up

The joyful serendipity continued because the same morning, Enphase’s product line manager Andrew Mitchell had arranged to drop into my office for a meeting. I told Andrew that tech support had foolishly suggested that I’d be out of pocket to fix their communications issue. Andrew was upfront:

“I don’t know what to say, Mark. That’s the Enphase policy. Enphase expects the installer to return and install a filter at their own expense. But I get your point, you installed to our installation guidelines and best practice. We really have no excuse.

He was right. They don’t have an excuse. So I got my keyboard warrior hat on and sent a passive-aggressive email to Enphase. It only took a week until Enphase conceded their attitude was wrong. Andrew knew I was working on this blog, so gave me the below statement to share with you.

 

As long as the product is installed, operated, handled, and used in accordance with the Quick Install Guide, Power Line Communications failure on a micro inverter is grounds for warranty replacement and Enphase will cover parts and labour up to 10 years.  If Enphase deems that the communications failure is due to environmental noise and not a product failure it reserves the right the remedy the situation with the use of a noise filter.  

That’s good news for installers. My faith in Enphase has been restored.

Enphase is developing a filter that should solve this issue. When the filter is available, we’ll be installing them in all of our Enphase jobs. Then we don’t have to worry every time our customer buys a new appliance.

In any case, the power line communication problem does not affect production. If it can be fixed by installing a filter, it’s not a massive issue. However, it’s not uncommon for Enphase to replace microinverters because of a communication issue that a filter won’t fix. Again, it’s not reasonable to install Power Electronics on a hot roof and expect nothing ever to go wrong.

 

Oversizing Enphase microinverters

I’ve been on a bandwagon for years, saying you should preferably avoid oversizing microinverters by 33%. String inverters often have panels in multiple orientations so they can “capacity share”. Microinverters can’t capacity share.

Enphase Comparison TestRecently I set up a side by side comparison on my roof attempting to quantify my argument. I installed 4x 320W panels. Two panels ran on 240W micro inverters (IQ7). The other two were connected to the larger 290W microinverters (IQ7+). I had some concerning anomalies from the IQ7+. I’ll mention those at the end of this section. But for this post, I’ll show my preliminary results which I think are conclusive enough.

 

Preliminary results

The blue production curve on the left is the actual production curve of 1 x north facing 320W panel in mid-September when connected to an IQ7 microinverter. The blue graph was traced from the Enphase portal to Adobe. The red section was extrapolated from the IQ7+ data. The area was calculated with an adobe plugin.

The IQ7 doesn’t reach the “peak output power” of 250W as per the Enphase spec. Instead, it starts clipping at 245W at about 9 am.

In September the sun is close to 90 degrees to the panels that are tilted at 25 degrees. So clipping will be close to the maximum.

The blue line was the actual production taken from the Enphase portal. The red line is “modelling” what an IQ7+ was reaching at the same time. It peaked at 295W.

The northern panel was clipped by 6.99%. The western panel wasn’t far behind.

This is only data from one perfect spring day. Without trying to predict 12 months of data, including rainy days, winter months, and different orientations, I’m close to admitting defeat. I would guestimate that the annualised losses from clipping would be approximately 2 per cent. If you work that out in dollar value, it’s probably not worth the cost of installing bigger microinverters.

If you are in Brisbane or further away from the equator, as long as your installer doesn’t oversize your microinverter by more than 33% (as per CEC guidelines), your annualised losses will be around 2%. An IQ7 is probably ok on a 320W panel and an IQ7+ can handle 385w panel. Yes, my Humble Pie was delicious.

But I’ll go down swinging with a few points you should consider.

  • If you install a 320W panel on an IQ7 micro inverter, don’t complain when your production flatlines in summer.
  • And the next time someone suggests that Enphase will yield higher because it handles panel mismatch so well: remind them Enphase can’t “capacity share.” Stick that in your pipe and smoke it.
  • Curveball: The anomaly mentioned showed the IQ7+ produces about 5% less than the IQ7 at times when clipping does not occur. Enphase has not given me an acceptable answer for this. I’m heading to Silicone Valley Mid October, and I hope to get insights at Enphase HQ.

 

Conclusion

Enphase microinverters have proven so far to the industry that they are a reliable solution. If you live in an area with extreme shade, we recommend using Enphase microinverters because they allow the panels to work independently of each other. Because of the flexibility of Enphase microinverters and the less intrusive installation methods, Enphase works well in townhouse and body corporate situations. However, rooftop power electronics will eventually fail. When they do, it could be a complicated and costly exercise to replace them. If you choose Enphase, you should also be aware of potential voltage rise issues, and understand that you are locking yourself into an AC Coupled Battery. Also be aware that if your monitoring is intermittent, noise from an appliance may be causing it, or a microinverter signal could have failed. The good news is, Enphase will now cover the cost of installing a noise filter under warranty. Finally, I was wrong. You can oversize a microinverter by 33 per cent without losing too much yield annually. Just don’t come crying to me when it clips 6.99 per cent of your power on a spring day.

Recommended Posts

Leave a Reply

Your email address will not be published. Required fields are marked

24 Comments on Enphase Micro-Inverter Review

Ian Schirmer said : Guest Report 3 weeks ago

The CQSola hardware and data system is the ONLY system in the world which does not clip. www.cqsola.com.au. CQSola is the only way to get all of the power from your panels all of the time.

  • 4129
Christopher Staples said : Guest Report a month ago

Same boat as Bill my enphase units are dropping like flys this year S230 with 250w panels facing West that rarely see 200w, 210w max so micro-inverters should not be getting over worked I am down to 6x working units a couple gone every month this year 2x on branch 1 4x on branch 2 and all dead on branch 3 only thing i can think of is line voltage being too high as when looking at peaks are about around the time something fails 230.80V min 253.17V max 240.31V Average 248.48V Current @ 1:45 pm

  • 4570
Billy said : Guest Report a month ago

Thank you so much for sharing! Looking forward to learning more.

  • 94931
Mark C said : administrator Report a month ago

Hi Esmail. I've written a blog that answers your question here: https://mcelectrical.com.au/blog/tilting-solar-panels-a-waste/

    Mark C said : administrator Report a month ago

    Hi Jake, Thanks. I met with Raghu, the founder of Enphase in USA last week. He said the issue is most likely with the tolerance of the ct inside each micro. So I'm going to set up a couple of wattmeters behind each panel and see if that adds up. It's the best explanation they have given me to date.

      Esmail Attia said : Guest Report 2 months ago

      I would like to hear your opinion on "Using Micro Inverter on Flat roof installation where MISMATCH can be an issue with production. and in Syd we tilt 30 deg using tripod, but I notice many jobs are installed flat due to COST , We will be glad to hear from you if its warrant to spend the EXTRA money on tilt gears Thank you Esmail Attia

      • 2196
      Jake Warner said : Guest Report 2 months ago

      Hi Mark, Another great blog. Im really interested to hear the response of Enphase about the IQ7+ slightly underperforming agains the IQ7 under normal operation. Cheers, Jake.

      • 2750
      Mark C said : administrator Report 2 months ago

      Ha Ha, exactly. 6.9 percent loss in 1 day!!

        Kenneth said : Guest Report 2 months ago

        Hi Mark, Interesting read again! And don't be too hard on yourself for not liking the clipping. My rational self may well be able to explain and understand the economical sense, but that irrational being sitting on my right shoulder would scream "losing money" in my ear every time I would have to look at those flatline graphs!

        • 2316DT
        Nigel said : Guest Report 2 months ago

        Hi Mark we have been installing enphase since 2014 with 300+ systems and over 5000 micros we have only had 5 units fail 2 were M215s they lost their firmware the remaining 3 were m250s they had their internal fuses blown. No s270 or IQ7+ have failed with our systems (We don't use the IQ7 and we move to the newest micro as soon as its released )

        • 7310
        Peter T said : Guest Report 2 months ago

        NFP Yes, I know Pete Thorne from Solaray. He is indeed well respected and I understand he does like to throw a technical curve ball now and then, that's for sure. I have only made his acquaintance online through the Tesla Owner's club.

        • 2902
        Mark C said : administrator Report 2 months ago

        Hi Peter, I confused you with a Pete Thorne, a respected business owner in the Solar industry :) My best advice around the matter is written in the blog: "Installing expensive and complicated power electronics on the roof, primarily to monitor the reliability of simple and affordable technology (diodes and panels) is madness." I'm not sure what you mean by "continuing to spin your wheels", but I'm being supercritical. Solar done right is easily worth it.

          Peter T said : Guest Report 2 months ago

          G'day Mark, Thnks for the response and the question, which is appreciated! As an end user, I am not in a position to know the degradation or failure rates of any specific panel(s), other than some of the horror stories you sometimes see in the news. Your critical point about good quality panels is shrewd advice for sure, perhaps even going to the point of selecting a supplier that might still be in business in 25yrs time also. However, I guess my question revoles around issues where a panel (or panels) can still be subject to a manufacturing defects/ tolerances or heavy soiling as just two examples that come to mind. I guess my question resolves down to asking ... is there another way (tricks of the trade you would be prepared to share) where an owner can use tools that might reasonably substitute for panel (level) monitoring? Your answer may have a big bearing on whether I continue to spin my wheels :-) Cheers Peter

          • 2902
          Mark C said : administrator Report 2 months ago

          Hi Peter! I'll ask a question back. (Genuine question). How many panel failures have you picked up compared to Micro Failures? From my experience, if you install a quality panel, you don't need complicated electronics to monitor it. But in this case, I am only relying on my own data.

            Mark C said : administrator Report 2 months ago

            Hi Peter. I know they will be available "soon". I think that means Q1 or Q2 next year.

              Peter T said : Guest Report 2 months ago

              PS Do you have any indication from Enphase as to when they might have IQ8s available in OZ and when their full Enphase Ensemble platform would be available also? Cheers Peter T

              • 2902
              Peter T said : Guest Report 2 months ago

              G'day Mark, Another great review mate ... well done ... and thanks. As you may be aware, I have been spinning my wheels for some time now waiting for more mature 3 phase solutions, and rightly or wrongly, have favored panel level monitoring for any number of reasons (e.g. early indicator of panels needing cleaning, real time reports, warranty monitoring, reduced safety risks etc). However, your comments beg question if I may ... and that is ... how does an end user monitor and/or determine (outside of each panel being monitored) where panels have degraded and/or failed below their warranted specs? Would appreciate your advice here mate ... Cheers Peter T ACT

              • 2902
              Gavan kelly said : Guest Report 2 months ago

              Was an interesting read thanks.Would be good to see Enphase vs string. That would be interesting

              • 2904
              Keiran said : Guest Report 2 months ago

              Thanks Mark! Another really interesting blog post. It will be interesting to see if there is anything behind the IQ7 outperforming the IQ7+ when neither are clipping. Please keep us posted :)

              • 3057
              Mark C said : administrator Report 2 months ago

              Hi Les, It's often not too hard on a simple roof. But if the panel is difficult to get to, you may have to remove multiple panels. If the end clamps or mid-claps have seized or they strip, it will get even more difficult - especially in time when it is near impossible to replace the same clamps.

                Les Winger said : Guest Report 2 months ago

                A very good analysis, especially of a comparison of Enphase inverters to string inverters. I was hoping for more words on Enphase vs. SolarEdge. The SolarEdge inverter would be much easier to replace than a Microinverter. but this is offset by the high failure rate of SoarEdge optimizers. And I don't know how much labor is required to replace an optimizer. Any comments?

                • 94024
                Dave said : Guest Report 4 months ago

                Hi i live near the beach and corrosion has been a problem in the past with guttering electrical fittings electrical boards in evap roof coolers etc so having an inverter in the garage makes sense. My kids live in a 2 storey town house near beach so weighing up the future service and corrosion costs being near salt water a stand alone inverter seems the sensible way to go

                • 3197
                Mark C said : administrator Report one year ago

                Hi Bill, interesting. I only had good experiences with Enphase and only heard good things about their reliability. But six or seven years would make it one of the earlier models.

                  Bill said : Guest Report one year ago

                  My experience with Enphase micro-inverters seems to be quite common: Expect a failure rate of about 50% within 6~7 years, horrible customer service (Enphase WILL NOT speak with owners), and not honoring their warranties. I would suggest anyone considering Enphase products do their due diligence research first. Enphase is unreliable junk in my book.

                  • 92054

                  Start typing and press Enter to search

                  Subscribe To Mark's Blog

                  Subscribe To Mark's Blog

                  Join our mailing list to receive the latest information, reviews and solar industry insights from MC Electrical owner Mark Cavanagh.

                  You have Successfully Subscribed!