[RE-wrenches] Solar Edge v. micro inverters

Sat Jun 15 08:57:51 PDT 2013

Marco –

As we are a SunPower dealer, there is really no question on which product to use for the 96-cell module (which we have a preference for over the 72-cell), as Enphase does not yet have a 300w or 350w micro-inverter yet.   To qualify our comments, have installed 14 SolarEdge systems and 10 Enphase systems to date.

>From our experience in New Mexico, we have branches from Taos to Las Cruces, but the optimizer v. micro-inverter choice is more important when the heat factor comes into play, as in Albuquerque and Las Cruces.  The most important advantage that I have seen is the ‘wider operating capacity’ of Optimizers and reliability of the optimizer/micro-inverter factors.   As all Wrenches on this list know, even if there is warranty labor compensation, a warranty call has its opportunity costs, as well.   I have outlined below my likes and dislikes of SolarEdge v. Enphase and most of them appear in the video on the link you provided, as well.

SOLAREDGE 

                Likes – 

Power Production - Better Power production in early mornings and late afternoons, give about 2.5-4% better AC production (at the REC meter!) than Enphase due to wider operating capacity of SolarEdge Optimizer

Free monitoring, can upload photos of customer site on monitoring portal, less AC wiring for gateways/dataloggers

DC powerline coms for monitoring use dedicated line from optimizers to inverter, therefore, no potential for ‘noise’ to disrupt the communication

No extra ‘trunk cables’ to buy

Lower cost/watt

Safe when in Open Circuit Voltage, where each Optimizer produces 1 volt until it is in 

Can use with SunPower 96-cell modules

Can now use star washers from optimizer to rail connection to eliminate need for #6 Bare Cu in exposed conditions

$125/per warranty call, to cover travel and labor

25yr Optimizer warranty

System cost decrease for increased system size

Arc-Fault compliant

                Dislikes –

                                SolarEdge stresses that a 25yr warranty can be ‘extended’, but is not standard – The 12yr warranty is a challenge talking point when customer is more concerned with this, than the viability of the company who is installing them

Failure rates of new products released ‘too early’ and are quite high – we experienced close to 40% failure rate of Gen1 inverter due to faulty I/O switch and motherboards which caused the inverter to ‘stay asleep’ when it appeared that there was harmonic ‘noise’ inside the inverter

Additional inverter equipment required to ‘interconnect’ and find a place for in a garage that has a lot of clutter

                                NEC Req’d Label calculations are a bit fuzzy, for the Imp and Isc conditions, may have initial questions from the AHJ.  

                                7000w inverter output is only rated to produce 6000w at 240 Vac, although allowable DC inputs are higher for the 7000 (8250

                                400w Optimizer is still a ‘new product’ and is having higher failure rates than 250w and 300w optimizers

                                Powerline adapter not included and will be an extra purchase

ENPHASE

                Likes       

                                Arc-fault compliant

Blog is great and answers a lot of technical questions without requiring to call tech support, Array of the week installs

                                MAGE solar is offering a 30yr warranty on the module/Enphase AC module product…interesting     

                                Safe when not connected (UL 1741 req’d)

Dislikes 

                                Energy Clipping on modules above 250w range in early years of production

EMU is extra and is not provided with Enphase purchase 

Lots of electrolytic capacitor electronics on the roof, in the heat, for a number of years

High Failure rates of m190 product

Max power limited to 215w micro-inverter at present, compared to SolarEdge’s 400w Optimizer for a single module 

Inverter AC output sizing is dependent on the micro-inverter size, whereas SolarEdge has one single inverter, this will come more in to play as Enphase increases micro-inverter sizing and will need to size Module to micro-inverter appropriately in larger systems  

Greater Voltage drop in longer homeruns, requires wire size increase

                                Online reporting is dicey, at times on some installations depending upon local harmonic distortions

                                Online monitoring only gives production ‘at the micro-inverter’ level.  

Note: This last comment is inherent in the product, so as a rule, always refer to Utility Revenue Meter at interconnection instead of online production values to be objective

Questions to Wrenches or Enphase/SolarEdge reps on this list:

SolarEdge (John B. and Marv D.)

1.       NEC req’d labels for inverter – Can we assume 350 Vmp and 500 Voc to calculate Imp and Max Isc values?

Enphase (Nick S.)

1.       Arc-fault failures were ‘repairable’ remotely via the online monitoring, but only 3 times.  Any update on this?

2.       When is Enphase coming out with a new higher wattage micro-inverter?

3.       What is Enphase’s compensation for warranty calls, travel and labor these days?

Either

1.       Which is better, one-on-one, in similar shaded situations

2.       Are there any reports of either products reducing effects caused by a higher Voltage Induced Degradation (I don’t know if this term exists [as opposed to PID]) for higher 600 or 1000v systems of modules operating at higher voltages per string

Congratulations to both Enphase and SolarEdge on their product development.  These products give us hope for higher performance and I expect to see an extended life of solar panels, due to these module level production units and will help hold module manufacturers accountable.  Congratulations to SolarEdge on their ‘Gangnam Style’ video, as well!

Regards,

Greg Seelhorst

NABCEP Certified PV Installation Professional

Las Cruces, NM

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of SwingJunkie
Sent: Saturday, June 15, 2013 5:25 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] Solar Edge v. micro inverters

Marco,

We installed our first Enphase system in December 2009, and our last in December 2011, when their high failure rate became a problem. (Currently 10%+ for us).  We were only installing the Enphase units on sites with shading issues, as a means to mitigate conditions. 

     After moving away from Enphase, we selected SolarEdge as the solution of choice for those sites.  The installation labor is comparable to the Enphase solution, separate device under each module. One clear advantage is that there are no custom trunk cables required, just the standard USE-2 cable and connectors. 

   Our field experience has been better than expected production, and 1.4% failure rate.  In December we installed a SolarEdge system just down the street from a site where we had previously installed an SMA string inverter on an unshaded site. The  SolarEdge system has some shading. Both arrays have roughly the same orientation and pitch.  To date the SolarEdge system with shading continues to out produce the unshaded SMA system by 5-8% kWh/kWp. 

I agree with your intuition on fewer components making a better solution and "IF" there is a reliable solution that accomplishes this that would be preferred. 

   I just priced out the Mage AC module (SolarBridge technology) side by side with the Mage - SolarEdge combination and the later is less expensive equipment wise but I think that advantage would be erased by labor savings on the install. 

   All that said I'm still a fan of the old fashioned string inverter solution unless the site shading conditions and or array geometry require an alternate solution. 

Cheers

Carl Adams

SunRock Solar

On Jun 14, 2013, at 9:15 PM, "Marco Mangelsdorf" <marco at pvthawaii.com> wrote:

I’ve been educating myself on the Solar Edge product v. using micro inverters.  If you click on the link below, you can read the pitch that they make for using their product over micros.  

Any opinions out there on how convincing their strategy is?  As well as any experience in the field with the product?

Intuitively, it seems to me that if you can accomplish what you need to accomplish (DC power from the PV mod to usable AC power) with fewer parts (as in a micro inverter instead of a DC-DC converter and a separate inverter), then that approach makes more sense.

http://www.solaredge.us/groups/us/technology/microinverters

thanks,

marco

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