Suntech Partners With Tigo For Solar PV Optimization

36 thoughts on “Suntech Partners With Tigo For Solar PV Optimization”

• Looks like a win win partnership. Tigo can improve new install efficiency or retrofit existing installs to improve efficiency. Tigo’s system is compatible with existing string tied systems. A retrofit would require different power connections. Easier on new builds.

  • How do they compare to solarEdge?

    • They are claimed to be more compatible with existing systems. Don’t know exactly why. SE uses their own inverter. I heard Tigo sometimes has had problems with the WiFi link. I like a hard wired comm link better, but Tigo should be able to make it work.

      • Tigo doesn’t make inverters, so they have to work with others’. Which is nice for retrofits, but I don’t think that’s the target of the PV-integrated module described above.

        SolarEdge optimizers would work fine with non-SE inverters too, assuming you manage to get their “safety and monitoring interface” that tells optimizers to exit the shutdown state they’re in by default; I’ve not seen it listed “in stock” anywhere in the US.
        New installs would surely include SE inverters instead, given how affordable are: they omit the MPPT and DC-DC already done by the optimizers.

        • SE inverters are inexpensive?
          https://www.google.com/search?q=solaredge+inverter&newwindow=1&client=opera&hs=ZOs&sa=X&biw=1914&bih=951&tbs=mr:1,cat:5142,p_ord:p,vw:g&tbm=shop&ei=Wg5CVrLZI8aq-QHb0Rk&ved=0CMkBEL0NahUKEwiy7pb8lobJAhVGVT4KHdtoBgA#spd=3617772899353682854

        • Yep, 18 to 22 cent/W is already pretty cheap to me, and like most string inverters, you can “oversize” the DC side, putting more solar modules than the inverter power rating.
          For the SE series, in climates like the US, the max is 135%, so if we were counting per DC watt at STC (the ratings used on the PV modules, which is what installers typically quote instead of the AC output), we’d reach 14 c/W.

          Can you find me another solar grid-tied inverter, true sinewave, 96~99% efficient, guaranteed for 10 to 25 years, UL listed and all that, for less? Let alone, from a reputable brand?

        • That would be another good article for CleanTechnica. Looking at the output of various inverters and measuring their stats.

        • FWIW, I have a 6 kW SolarEdge inverter (SE6000A). Its own reporting very closely matches the revenue-grade meter next to it, and it maxes out at exactly 6000 W AC +/- less than 1%, regardless of small line voltage fluctuations.

          The inside seems overbuilt (of course I opened it) 🙂
          I suspect that its guts are the same as higher-capacity models, with just a different output power limit set in software.

        • So it sounds like you put in more energy than it can handle. Once it reaches max it only takes what it can convert and you don’t have to worry about it acting like a load bank and overheating?

        • Yes. Most of the time, PV modules produce less than their rating, so it’s common to put a bit more than the capacity of the inverter (micro or not).
          Even when this isn’t done, modules can produce peaks well exceeding their rating, e.g. when clouds open up: modules are still cold (more efficient), and receive not only direct sunlight, but also reflections from surrounding clouds.

          Inverters do just like any other appliance, they take in only whatever current they can use, all the way down to zero if they’re shut off.

          What you might have had in mind are small wind turbine controllers. Those usually do include dump loads, to keep the turbine from spinning too fast.

        • That’s good to know. I mistakenly thought the inverters might burn if supplied to much power.

          Also did not know surrounding white clouds could help with power.

          Thanks.

        • Well, I just found out that the California Energy Commission has tested tons of solar inverters over the years, and publishes for each its efficiency curves and maximum output.

          Have fun. 🙂

          http://www.gosolarcalifornia.org/equipment/inverter_tests/summaries/

        • I immediately checked the 2015 SE and EP inverters. They are pretty much identical efficiency wise. Almost same curves.

          I’ll bookmark this page. Useful information!

        • Yes. My impression is that the SolarEdge works better with SE optimizers because all the bells and whistles work together. Some of those are pretty useful, like the no output when the PV is down, and no output when the grid is down. Someone mentioned some fire standards, too.
          The SE inverter will still work with other systems. And optimizers could work with other systems as you say.
          The thing is, most existing inverters have MPPT built in. Not a problem, but its redundant when adding optimizers.
          Maybe thats why SE has pretty low cost inverters, I don’t know.
          And the PowerWall has a DC-DC built in at least in part to provide charge controlling and interface between the variable input voltage and the variable battery voltage.

          All this makes me want to take a big picture view of the system and simplify and make it cheaper and more robust.
          I hate they idea of having redundant circuitry. The optimizers are DC-DC. Their output should be able to drive the battery directly.
          The optimizers could potentially be directly tied to both the battery pack and the inverter input. Scratch one extra DC-DC. Lower cost.

        • SolarEdge inverters indeed lack the MPPT and input DC-DC present on normal string inverters; those functions are in the optimizers.
          I’m sure that avoiding this multi-kW DC-DC is in large part responsible for the low price of SE inverters.

          Using them without optimizers (and therefore without MPPT) will work in some circumstances (just the right string length, etc), but the power output will surely be disappointing.

          Optimizers (at least SolarEdge’s) only energize the line when the inverter tells them to. They will cut power if the inverter shuts down, disappears, or if a fault such as overcurrent or arcing is detected.
          The standard you think of may be the 2011 NEC section 690.11, which requires arc-fault protection for PV circuits.

          Being able to effectively disconnect every single PV module also allows those systems to exceed the 2014 NEC 690.12 “rapid shutdown” requirement, with all parts being completely touch-safe when off.

        • Yes. Nice feature. The DC-DC isolates the panels from the inverter and from each other. There is no series voltage except what the DC-DC provide. That ought to be the feature to have with firemen on the roof for one. Also seems like it could be good fire prevention.

      • What about battery?

        • Look at the diagram and post I wrote. They use a bidirectional inverter and battery on the AC side. They call it an AC battery. That just adds on to the existing system.

        • @disqus_MOZiUpcqXO:disqus covered the Enphase aspect.

          For the optimizers: Tigo’s work with inverters from SMA and Fronius, companies which also offer battery-backed hybrid on/off-grid inverters. Done.

          SolarEdge apparently supports connecting a battery directly on its DC side. I like how simple and elegant this looks.
          http://www.solaredge.com/files/images/home/StorEdge/storedge_self_consumption_and_backup_power_top_banner.jpg

      • The other day when we were talking pricing between SE and Enphase I just assumed Enphase was more expensive. Now that I’m looking at the prices it seems Enphase is about half the price. A little more expensive than the SE module but once the SE inverter is thrown in it seems to be about double the price of an Enphase system. Am I missing something?

        • Don’t know. Lets compare notes. I did a quick Google search and found some ads. Heres what I get:

          An Enphase AC battery diagram.
          http://www.freecleansolar.com/v/vspfiles/assets/images/Enphase%20AC%20Battery%20connection%20grid%20PV%20load.jpg

          From the diagram, and what I read, each of those boxes has a battery in it, and they also have a bidirectional inverter and must also have a DC-DC to control the battery charging.
          That duplicates the micro inverters on the rooftop. They claim the approach is good because it can introduce owners to storage in incremental steps. But the steps are small, about 1.2kwhr. And a bit more expensive.

          When you add up the micro inverter costs and all the other parts of the system, that works out a bit more expensive than other systems, but not bad. You can see the prices in the reference below.

          I don’t know why it could not be designed for standby, according to this they do.

          “The Enphase AC Battery system is a modular, plug-and-play energy storage and backup power solution. The fully integrated Enphase Energy Management System consists of the AC Battery, bi-directional S-275micro-inverter, and the Envoy S communications gateway. Electricity can be stored from the PV solar panels or the utility grid. The backup power can automatically switch on in the event of a grid outage. The adaptive system learns how to optimize electricity usage and savings over time.”

          http://www.freecleansolar.com/…

          IMO, its not an optimal or desirable solution.
          They are going to get beat in Hawaii by SolarEdge, SolarCity, and PowerWall.

          Its just a better system for storage. Enphase is good for grid tied solar only. Hawaii killing net metering has left them with few cost effective options to add storage. And the batteries are LiFeP. Those are not so cost effective for energy storage. Still a good battery, but the cost/kwhr isn’t as good.

          PowerWall is 3k for 10kwhr. Enphase AC battery is $500 for 1.2kwhr. Its about one third more expensive. Thats not too bad.

          A 250 W M250 microinverter is $150. I found prices lower and higher. A 2.5 kw system will cost $1,500. I can get a SolarEdge 10kw inverter for $2k. The optimizers are $77 each.
          Enphase requires a combiner box for $1k. Pretty sure SolarEdge is less costly.

          So lets add it up. For 2.75kw

          Enphase.

          10 x 240 uinv ea. = 1,500
          1 x combiner = 1,000

          total = 2,500

          SolarEdge

          10 x 77 optmzr ea= 770
          1 x inverter 3.3k = 1,330

          total 2,100

          If you drop the combiner, Enphase is a little cheaper.

          Now I did not include labor and installation. When I look at install videos, there is some stuff for both that you might want an electrician for.
          So I don’t know about that part, but I assume its not a big difference. The roof installs are similar.

          I can say this. When you get to 10kw, and the larger you go, the cheaper SE is by comparison.

          A 10kw SE inverter is only $2,000. The 40 optimizers cost 40×77= 3,100. So the system cost is $5,100. But a 10kw Enphase with 40 inverters costs 40×150=$6000. And that does not include the combiner.

          So if its small and you are grid tied only, go ahead with Enphase.
          If it gets bigger than that, think about SE.
          But here is the thing. I don’t see why you couldn’t start with string tied and switch to SE later if you wanted. For that matter you could switch to Enphase. Its a bit of hassle, but not too different from the initial install, particularly for SE. A string tied inverter has the same 400V DC going from roof to inverter, so thats the same. (except the inverter is better if its SE already, but with those prices might as well).
          But with Enphase you have to wire AC from the roof.
          Both require code. Both require inspection.

        • I haven’t read much of your reply but it looks like you are putting batteries into the system. Most people, 99% or more, use the grid as a battery. So I’m talking prices for most people. I’ll assume with a battery SE would be cheaper. Without battery I’m thinking Enphase is half the price…?

        • Enphase is nowhere near half the price without a battery.
          10 250W micros are $1500. A 3kw box inverter is $1300. But a 10kw inverter is only $2000.

        • So each Enphase is about $20 cheaper, $130 vs $150, but doesn’t need the $1300 to $2000 inverter. Apparently a combiner is needed on Enphase that is somewhere between $381 and $835 depending on the size of the system. We need articles on these subjects. I’m sure there are things I’m missing which people who do this for a living probably understand.

          https://www.google.com/search?newwindow=1&client=opera&hs=PPy&biw=1914&bih=951&tbs=vw:l,mr:1,p_ord:p,brand:enphase&tbm=shop&q=enphase+m250&sa=X&ved=0CJ4BELMrahUKEwjQ99aK7YbJAhXFXBoKHVPIAIY

          https://www.google.com/search?q=enphase+combiner&newwindow=1&client=opera&hs=sQy&biw=1914&bih=951&tbs=vw:l,p_ord:p&tbm=shop&ei=AWlCVoGqNIP_abaVieAH&ved=0CGoQuw0oAWoVChMIwa6itu2GyQIVg38aCh22SgJ8

          https://www.google.com/search?q=solaredge+inverter&newwindow=1&client=opera&hs=OSy&sa=X&biw=1914&bih=951&tbs=vw:l,mr:1,cat:5142,p_ord:p&tbm=shop&ei=X2lCVrOXE8WRaPThjvAI&ved=0CM8DELsNKAFqFQoTCPPC6uLthskCFcUIGgod9LADjg

        • No. Optimizers are only $77 per module. Micros are $150/module. Optimizers are half the cost of micros, but then you add the cost of the inverter.

          I gave the numbers I found for a 3.3kw inverter, because inverters don’t come in small increments of kw. You can just look at a single 250W micro and calculate that at $150 ( and the price varies up and down) and figure
          150/250 gives $600/kw. And a 3.3 kw box inverter for $1300 gives $400/kw.

          Then you deal with the optimizers. The are one per module, lets say a 250W module. So thats $308/kw. But that doesn’t count the combiner at $1k.
          So without a combiner, Enphase is a bit cheaper for a smallish system. I don’t know if you can make the Enphase work without it.
          But when you go to bigger systems, the box inverter cost/kw drops a lot.
          A 10kw inverter is only $2k. Thats only $200/kw. So for higher power, Enphase is definitely more expensive at higher power.
          Box inverters get really cheap at high power.

        • Nor sure where you get your idea that Enphase is cheaper. Optimizers are 50~80$ per PV module, much less than any micro-inverter (note how the more expensive optimizers handle two modules each).
          Cabling is also trivial: just chain the stuff, exactly like plain-vanilla PV strings.

          With Enphase, you must use their proprietary “Engage” cable which adds 20~30$/module, and the labor to end/splice them, install junction box(es) etc, because it’s not like you’ll run their expensive cable all the way to your breaker panel.
          Each AC circuit max out at 3.8kW, so you may need to run multiple ones to your roof (or add a breaker panel up there? More $ either way).
          Also add 400~500$ for the monitoring gateway, if you want to have any clue about what the system is doing.

          Micros may work great for small systems, but get quite expensive over a few kW.

        • Agreed, and I think that the cost balance is even more in favor of optimizers-based systems than you picture.

          SE optimizers are in the 60~70$ range. For large systems, one might go with e.g. P700s instead, which handle two PV modules each, lowering the cost to 50~55$ per module.

          This brings your 10kW setup to ~4k$.

          For Enphase, you forgot their required proprietary cabling, which is quite expensive at 20~30$ per plug. Monitoring adds another 400~500$. This bumps up the same 10kW to ~7.5k$ (again, just for the Enphase hardware).

          Which system is better/cheaper will ultimately depend on many other considerations anyway, a major one being labor/installations costs.

        • Yes. Thanks for the details. There is that Enphase combiner box, I think they call it.
          To my mind, several aspects of the micro inverter concept are at a disadvantage. Chief, is that battery storage is unnecessarily complicated. Its also nicer to bring more electronics under the roof where it gets better environmental conditions.
          The roof is a harsh place for electronics. The optimizers have less electronics on the roof. I prefer that.
          Fundamentally, all the details are adding up to MLPE optimizers ultimately winning on cost.
          But I do think they need some improvement on diagnostics to find a bad optimizer, and they need to extend the inverter warranty to 25 years. At that point, they become compelling.

          The whole storage thing is another matter. IMO, its just no contest. There is no sense in converting to AC and then converting the AC back to DC to charge the batteries. The Enphase system duplicates a lot of electronics hardware doing that. I think most get that idea.

        • SolarEdge already offers 25-year warranties on both optimizers (standard) and inverters (extra $; same product).

          Not sure where you think diags should be improved. Both the portal and LCD on the inverter display the status of each optimizer, so it should be trivial to tell if one isn’t behaving, including where it is, assuming the installer did record the layout correctly (otherwise, follow the wiring and check the serial numbers).

          What’s ultimately more important IMHO is to not have things fail the first place. SolarEdge’s SEC filings seem to validate its reliability claims, as it spends less than most its competitors on warranty obligations (9M$ out of 325M$ revenues for FY2015).

        • Do the SE optimizers still report correctly when one has failed? Thats what you need. Otherwise its the Christmas tree light story. Do you have info about whether the diagnostics work after units fail? If they do, the one that don’t report are culprits.

        • I’ve looked hard for online reports of failed SE optimizers. I found only a few occurrences; most were optimizers not reporting, while apparently still producing just fine.
          Unsurprisingly, in no case was the rest of the system affected.

          The SE portal paints each module with a color showing how much it produced. Discrepancies would instantly stick out (and outright disappearances ought to trigger alerts too).
          http://expo.solaredge.com/EN/images/pic-lvl3-6.png

          Each optimizer must include a fat bypass diode, so current continues to flow even if itself is sleeping or dead. I have a few modules facing east; those wake up and shut down before the others, no biggie.
          Think of a string of optimizer not as old Christmas lights, but as batteries connected in series with diodes across each one. Lose one, and the only effect is lower total voltage (which other optimizers will compensate for); full current capability remains.

          SolarEdge doesn’t explain how its DC line communication works, but it could leverage positive, negative and ground, making it impervious even to a cut in any one of those.

        • It makes sense. As long as each optimizer is powered by its own module, any powered optimizer should be able to report, if the comm systems is designed properly.
          And the diode thing really should be done on any string PV. I heard complaints that the optimizers could be difficult to debug. I wonder if bad installation was a problem or shortcuts were made. Its always hard to evaluate those kinds of complaints about any technical system. Without specifics, its difficult to judge.
          I note also, that more than once I have read that some warranty or function problems have had to do with communications, not PV function. That seems to be true of all MLPE.
          SE communication is a hard link. The only way it would force a tech on the roof is if the comm link failed completely, and I don’t know why one unit failing would kill the whole link.

    • SolarEdge inverter, has it got off grid function when the grid down?

      • They claim they do.
        I don’t see any technical reason why they couldn’t.

• cool article and awesome comments…..

  • Would love to see @evee & @GCO spec a 10kw system using SE products & panels of there choosing. With battery, grid tied for a home in central Texas with a beautiful south facing (60-65% of 10kw) and west facing roof line.

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