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Tigo EnergyTigo Energy optimisers are the quiet achiever of the Solar industry. In part one of this blog, I’ll explain how installing solar panels in shade will affect your solar production. I’ll show, through a series of tests, how solar panel bypass diodes work reasonably well to combat shade, but I’ll also explain why solar panel diodes are not the solution. Next, I’ll explain how Tigo optimisers work, and I’ll give three reasons why Tigo optimisers are significantly better than bypass diodes. In part two, I’ll discuss why I believe Tigo is a better solution that SolarEdge. Then I’ll discuss my findings on the Tigo optimiser failure rate, and I’ll expose two weaknesses of Tigo Energy.


About Tigo Energy

Tigo Energy is a Californian based solar panel optimiser company. They began in 2007, and today they operate with a lean 45 staff worldwide. Only one of their staff, Jeff Routelage, based in Australia.

Interestingly, it’s an Australian who is the patent-holder for Tigo Energy’s core technology. I emailed Peter to ask him about his invention. He replied:

Nearly 20 years ago I had a solar car team and I developed some single cell maximum power point tracking devices. This resulted in some patents on distributed maximum power point tracking that were held by my university on my behalf …. Tigo Energy built their business in the US and then found they overlapped my patents.  They asked for the rights to use my patents and I agreed to sell them these. I was quite happy that they saw some value in my work.

Professor Peter J Wolfs
CQ University, Rockhampton Queensland

That’s good enough for me. Tigo optimisers are an Aussie invention.
In 2016, inverter manufacturing giant SMA bought 27 % of Tigo Energy. I reckon SMA were onto something. This blog explains why.


Part one: Why we need optimisers


solar panels in shade

solar panel bypass diode

Shade is no friend of solar. In fact, just a little bit of shade on one solar panel can reduce the output to all of your panels. When solar panels are “daisy-chained”, or wired together in series, shade on one panel acts like a kink in a hose and reduces the output of the rest of the solar panels.

Going on this logic, let’s say we had ten panels all producing 200W, a total of 2000W. Suddenly one solar panel is partly shaded and can only produce 100W. If the logic above follows, then every panel could only do 100 W, so we would lose half of the power just because of one solar panel in shade.


Solar Panel Bypass Diodes

solar panel bypass diodesIn reality, solar panels work better than that, thanks to the help of solar panel bypass diodes. Solar cells within a panel are usually wired in 3 columns called cell strings. Each cell string has a bypass diode connected to it.

If a panel is significantly shaded, the solar panel diodes will engage. As a result, the shaded portion of the panel will be bypassed. The shaded cell string won’t produce any power, but at least it won’t drag the other panels down. That’s the theory, now time to test it.

Introducing Tigo TS4M

The product that made my testing so much fun was the Tigo TS4M. The Tigo TS4M is a dumbed down version of a Tigo optimiser. It’s a device that monitors what a panel does but doesn’t optimise.

You may think it’s a dumb idea to pay extra just to monitor your panels. But for testing how solar panels react to shade without an optimiser, the Tigo Ts4 is a perfect tool. When a bypass diode engages, the panel voltage reduces by a third – and the Tigo monitoring reveals this. In the image below, a bollard is shading the middle panel on one cell string, so the voltage is reduced by one third.

tigo optimisers

Volts from panels – One bypass diode has engaged

How much shade do you need before a solar panel bypass diode engages? First I set up two strings of panels as shown below. I then ran multiple tests, shading with fly screen, stink pipes, rail, branches and fold up tables. I was up and down the warehouse roof almost every day for a month. This paper pusher rediscovered his calf muscles. Here’s a summary of what I learnt the hard way.


Tigo optimiser shade test

Tigo Energy optimiser


Unoptimised panel results

  • Figure #1. Partial shade on four cells does not activate a diode, so all five panels are dragged down.
  • Figure #2. A vent pipe partly shading one cell does activate a bypass diode. Production of a third of 1 panel is lost.

Solar panels in shade

  • Figure #3. Partial shade on six cells activated a bypass diode. Production of only one cell string is lost.
  • Figure #4. Heavy shade on three panels across 1½ cells. Bypass diode does not engage so all five panels are dragged down.

Solar panel in shade


When solar panel diodes work

It was interesting how easily one bypass diode engaged when a single panel was in partial shade (fig 2 & 3). In figure 4, when three panels were heavily shaded, the bypass diode did not engage. But this was actually the best option: had they engaged, the entire string would have shut down due to a low string voltage.

How does a simple solar panel bypass diode know when it is best to bypass and when not to?

The inverter tells it!

The job of the inverter’s Maximum Power Point Tracker (MPPT) is to dictate the current and voltage, so the entire string produces the most power. Sometimes this means the inverter lowers the current so low that the bypass diode does not engage. Sometimes it increases the current so high that a little bit of shade activates the solar panel bypass diode.

What I found interesting is how effectively this inverter and solar panel bypass diode interaction works. In most cases, the bypass diodes significantly reduce the impact of shading.

So if solar panel bypass diodes are doing a good job, why the need for solar panel optimisers? Lets first look into what the optimiser does.


What is a solar panel optimiser?

A solar panel optimiser is a black box of power electronics that you can install behind solar panels to allow each panel to work more independently of the other panels.

Each brand of optimisation does this slightly differently, but Tigo Energy does it by “impedance matching”.

/ɪmˈpiːd/ To delay, prevent or restrict (someone or something) by obstructing them.

/ɪmˈpiːd(ə)ns/  A fancy word that has close enough to the same meaning as electrical resistance. Impedence restricts current flow in an electrical circuit. Shade on a solar panel will cause impedance in that panel.

Before a bypass diode has the time to engage, the Tigo optimisers see the impedance caused by the shade and open a bypass tunnel to match the impeded current. This allows the inverter to work at a higher current without affecting the solar panel bypass diode.

Tigo Energy impedance matching

Bypassing the current from higher panels around a bypass tunnel is a far more effective method than relying on a bypass diode for at least three reasons:


Reason 1 – Optimising prevents shaded solar panels from dragging the entire string down.

One of the shade tests I performed showed what happened when solar panel diodes do not engage.

Tigo optimiserIn this test, the left three panels were significantly shaded. To prevent the inverter from turning off from under-voltage, the inverter reduced the current, so the bypass diodes did not engage. This meant each panel still produced 30 volts, but only 0.5 amps.


Tigo Energy monitoringWith the same amount of shade on the optimised panels, the shaded solar panels performed poorly. But the unshaded solar panels were able to run at a higher current, (so higher power). That high current was redirected through the Tigo optimisers on the shaded panels.


Reason 2: Optimisers allows partial production on shaded solar panels


Solar panel in shade

Optimised panel. Diode did NOT engage.

Solar panels in shade

Unoptimised panel. Diode did engage.

When I compared scattered shade on an optimised vs non-optimised panels, the advantages of optimisers were clear. The optimised panel still produced 20 watts while more than a third of the panel was in the shade. The non-optimised panel was bypassed with minimal shade.


Reason 3 – Solar panel diodes are not optimisers

The primary purpose of a solar panel bypass diode IS NOT to increase production but to prevent panel damage caused during shade. If bypass diodes were not installed in solar panels, the shaded section of the solar panel would have a high resistance. The high resistance will cause excessive heat as current flows through. So solar panel bypass diodes are primarily designed to prevent damage caused by hot spots from infrequent shading.

Diodes are a simple semiconductor device with a limited duty cycle. The more the solar panel diode engages, the shorter its lifespan. If you install unoptimised panels in significant shade, the bypass diode will eventually fail, and your panel will no longer be protected from hot spots. Interestingly one of the more reputable panels, LG, state that their panel warranty does not cover:

Improper installation or reinstallation and poor solar system design. (Examples of improper installations and very poor system design are modules installed in conditions which put long term stress on the bypass diodes in the modules, and also reduce the system output for the owner – for example prolonged significant strong shadowing of the modules e.g. via trees, walls, gables, overhangs, valleys, chimneys, satellite dishes etc (In such situations a professional solar designer will suggest a micro-inverter or optimiser solution and with such a proper solar system design solution the module warranty is fully applicable).

While not specifically stated in many other solar panel warranty documents, most panels brands have the same issue. (Sunpower’s Maxeon cell is different from others, but investigating how Sunpower panels respond to shade is for another blog.)


Part 2: Why Tigo Optimisers

We’ve identified that Solar panel optimisation not only increases your production, but it also protects your solar panel diodes. In reality, there are only three optimisers in the Australian market, Tigo Energy, SolarEdge and Huawei. So why Tigo Energy?

The simplicity of Tigo Optimisers

One aspect of Tigo optimisers that makes it stand out from SolarEdge is the limited work Tigo optimisers are required to do. SolarEdge optimisers require you to use a SolarEdge inverter. The SolarEdge inverter does not have a “Maximum Power Point tracker”  (MPPT) and as a result, it requires each SolarEdge optimiser on the roof to continually adjust the voltages and current throughout the day to achieve the Maximum Power Point.

In contrast, when you use Tigo optimisers, you choose any brand of inverter. It’s the job of that inverter to do the heavy lifting of the Maximum Power Point Tracking. The Tigo optimisers get off easy and are only required to work when their panel is “impeding” the other panels.

While Solaredge optimisers are forced to work anytime the sun is shining, Tigo optimisers are only required to work when the shade is … shading.

This simple Tigo Energy architecture has two clear advantages

  1. If your inverter fails outside of warranty, you can replace it with any brand of inverter.
  2. The power electronics on the roof are required to work significantly less, logically increasing their lifespan.


Tigo optimisers are better in shade

In my SolarEdge post, I showed how SolarEdge usually requires a minimum of 8 panels to operate efficiently. This is because the SolarEdge inverter requires a combined 360 volts from all the optimisers, and standard optimisers only boost to a maximum of 60 volts. If you have less than six panels un-bypassed, the inverter will go offline. In short, the SolarEdge system does not work well in heavy shade.

Tigo is different. We would normally match Tigo optimisers with a Fronius inverter which has a minimum voltage of 80 volts. All the inverter needs to operate is three un-bypassed panels.

If you want to understand SolarEdge better, read my SolarEdge review.
And if you want to know what I think of Huawei, read my Huawei review.

Tigo Energy Selective deployment

One of the advantages Tigo Energy has over SolarEdge is you get to choose which panels to optimise. If you only have one or two panels that will ever be in the shade, you can optimise just them. Selectively deploying optimisers has taught me a lot about the importance of optimisation. I ran a test on panels on my warehouse to demonstrate:

Solar panel bypass diode

Bollard shading

Using the same installation, I removed the Tigo optimiser on all panels except two. I placed bollards and posts in front of panels to mimic vent pipes.

As the shadow moved over the unoptimised panels, I could see bypass diodes kicking in and out. When the shade was not significant enough to engage a diode, the shaded solar panel dragged down the rest of the array.

The optimised panel performed significantly better. Not once did a bypass diode engage with this level of shade, and the unshaded solar panels saw no loss in production

Selective Deployment not only cuts down on cost, but it also reduces the number of power electronics sitting on your roof. If there is one thing I learnt from SolarEdge, it is that power electronics can and will fail. I don’t care what bells and whistles you get with this fancy module level power electronics. If you are interested in reliability, you might consider avoiding wacking a bunch of power electronics on your roof – unless you absolutely need to. But should I tar all optimisers with the same SolarEdge brush? How reliable are Tigo optimisers?


Tigo Optimiser Failure Rate

My problem with analysing Tigo optimiser failures is that most of the Tigo Energy systems we selectively deployed without monitoring. We have only installed six measly systems with full monitoring, and one of those is at my office. So I called a bunch of installers who have monitored Tigo Energy systems. I talked to nine installation companies who had anywhere from 2 to 30 sites monitored. Some of these sites were commercial sites and had over 1000 Tigo optimisers. The total number of optimisers for this sample was almost ten thousand. I asked three key questions:

  • How many Tigo optimisers you have you installed?
  • What is your failure rate on TS4 optimisers or earlier Tigo products?
  • Are you sure there are not more failures?

The two companies with the larger sites told me they had someone in their office that checked the systems weekly or monthly. They can do this because it only takes a couple of clicks on the Tigo platform to check. The other companies were not so diligent, so I asked for their Tigo portal logins and manually checked all systems myself.

The results

To summarise the commonalities of the feedback I received:

  • Many had failures with Tigo Energy products before Tigo released their TS4 optimiser.
  • Most of the issues were with embedded panels, (the optimiser is sold as part of the solar panel) and were a result of ribbon failures. It’s a fault of the panel manufacturer.
  • Everyone said Jeff Routledge from Tigo Australia is legendary for his technical and warranty support.
  • One person reported one Tigo TS4’s failure.

ONE failure in about TEN THOUSAND optimisers. Ok, take that with a grain of salt, I hardly believe it myself. I asked Jeff from Tigo how many reported failures Tigo Australia had.

FIVE TS4 failures claimed in Australia.

Na, I like Jeff, but he must be counting wrong. That’s stupidly unbelievably reliable. But Jeff read this blog before I published it. He puts his good name to his bold claim. Have you had a Tigo TS4 failure?

Tigo Energy Monitoring

If you choose to purchase Tigo Energy monitoring, it comes with individual panel monitoring for the customer as the base offering. While the amount of information we can gather from the Tigo portal is impressive, it does not tell us what is happening at the inverter level. But that’s easily fixed. We use Fronius inverters, which has the best inverter monitoring available. While it’s not perfectly elegant having to use two websites to get your data, the level of monitoring you get is second to none.

One small confusion between the two platforms is that production figures are different. This is because Tigo records the daily kWh before the inverter, but Fronius record the daily kWh after inversion. Because there is always an efficiency loss through the inverter, Fronius records a lower production figure than the Tigo Energy platform does.

Tigo Alerts

Tigo Energy offers basic alerts via email or SMS. If you subscribe to premium for another $20 a year you get production alerts, in theory giving you alerts when you have lower production than expected from a panel or an array.

I jumped on the roof to test how well the alerts worked. I started off slowly by shading the panels, but it was obviously not enough to trigger an alert. So I got serious.

Tigo Energy monitoring

  • First I replaced 300 w panels for 190W panels and removed and shorted bypass diodes.
  • Next, I shaded several solar panels with varying amounts of cardboard and fly screen.
  • In an attempt to fry a Tigo optimiser and trigger an alert, I connected 4 x 345-watt panels in parallel into one optimiser. These bad boys are unstoppable; I couldn’t kill it.
  • Finally, I had success at blowing up a Tigo optimiser by putting three panels in series and running 120 volts through the optimiser that would normally run at 35 volts or less.

I set my premium alerts to send me alerts every day via text message and email. However, the only alerts I received were daily heartwarming congratulations about my system’s outstanding performance, including this one:

Considering this system produces 60kWh the day before, I don’t think 0.1kW deserved congratulations. I never received a low panel performance alert or a failed optimiser alert. I never received a single text message. Fair to say Tigo premium alerts currently don’t work. Tigo has advised me they are working on it. I’ll update this post if they get it working.

Tigo Energy marketing

And I’m going to have one more jab at Tigo. The Tigo Energy sales and marketing department is … underwhelming. SolarEdge has gained market dominance with a product that is fundamentally flawed. Imagine what the SolarEdge sales and marketing team could do if they marketed a product like Tigo!


While solar panel bypass diodes work reasonably well to reduce the impact shade has on performance, it is not what they were designed for. If a solar panel is installed in significant shade, an optimiser should be used. Optimisers not only increase solar production, they prevent bypass diodes from burning out. Tigo optimisers are a superior optimiser because of the simplicity of the design. They perform better in heavy shade, can be selectively deployed, and are only required to work during shaded times. It’s not surprising then that Tigo optimisers seem to be far more reliable than SolarEdge. Tigo still has issues: their premium alerts are not working. But if Tigo Energy were to up their marketing, they deserve to gain more market share.

34 Comments on Tigo Energy Optimiser Review

Michael said : Guest Report 6 days ago

Hi Thanks for the report on the Tigo Ts4 optimisers. I have a question. Can they be useful if your panels are spread over multiple roof surfaces but with no shadowing problems. Is an SMA inverter okay with the Tigo Ts4 Thanks Michael

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Mark C said : administrator Report a week ago

Hi Anders. Probably not that beneficial for early morning and evening, but if you have shading between about 9 am and 3 pm in winter, I think optimisers would be worth it.

Anders Wittesjo said : Guest Report 2 weeks ago

Hi! Do I need optimisers for partly shaded panels when the solar radiation is low, for example in the morning, evening and in the winter?

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Mark C said : administrator Report 4 weeks ago

Hi David, I can imagine they wouldn't be as much of a help in a small mobile situation. They really need a longer-strings than 2 or 3 panels to work well, and they have to co-operate with the MPPT. But - it couldn't hurt to try it out!

Mark C said : administrator Report 4 weeks ago

Hi Jeff, My first option would be to use Tigo optimisers selectively, then Enphase.

Jeff K said : Guest Report a month ago

Mark, I am looking to go solar soon, potentially 27 LG 365 panels or so on my residential house. I have a chimney and a couple sewer gas vent pipes that will give some shade on parts of my south (sun) facing roof mostly in the colder season (I am in the U.S.). My question is, at this point, do you recommend microinverters or optimizers? I was considering Enphase and SolarEdge and was leaning toward SolarEdge until I read your article about them, but now i'm not sure which to go with for reliability and safety. What product do you recommend now for partial shaded roof? Enphase microinvers or Tigo optimizers or something else? Thanks, Jeff K

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David said : Guest Report a month ago

How would these go in a mobile application? I live on a boat with 850w of solar on the roof but thanks to shading from mast and boom and ropes, and flat orientation, the most I see is about 350W. The string is connected to a pretty clever MPPT solar charge controller (Midnite Classic 150) keeping 400Ah of LiFePO4 topped up. I'm looking to renew the panels. Would the TS4's make a significant difference? Can they work without the monitoring function?

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Chris J said : Guest Report a month ago

Thanks for the explanation, Mark. I will do as you advise and optimise east and west.

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Mark C said : administrator Report a month ago

Hi Chris, Id need to see the layout. It's often better to put Tigos on all panels if there are multiple orientations, especially when you are 180 degrees opposite orientations. Because Tigo doesn't boost voltage, when the unoptimised panels are in less sunlight, it will limit the current (and power) of the optimised panels. If it were only 2 or three panels that were limited, that's no big deal, but limiting 5 panels doesn't sound good.

Mark C said : administrator Report a month ago

Hi Lindsay, no. SolarEdge inverters need SolarEdge optimisers to work. One won't work without the other. SolarEdge optimisers buck (decrease) and boost (increase) the voltage. Tigo only bucks.

Chris J said : Guest Report a month ago

Fantastic blog that contains the perfect information for my situation. It could not be more timely. My proposed design is Fronius inverter with 3 panel arrays (N/E/W). East and west into a single MPPT with the Tigo optimisers on the 5 east facing panels. No shading at all. North panels into the other MPPT. Though obviously not shading related, the optimisers will provide maximum generation. Do you see any issue with this arrangement? The two other companies I've discussed the design with push me straight towards SolardEdge, and one said the do not sell the Tigo optimisers at all. This, yet again, felt like companies pushing their own agenda rather than trying to get me the solution I want.

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Lindsay said : Guest Report a month ago

Do Tigo optimisers work with a Solaredge inverter? Certainly the Solaredge optimisers do the MPPT work but do Tigo optimisers placed on all panels also do the MPPT work?

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Craig said : Guest Report 2 months ago

I’ll be keen to hear what you discover in that testing. The prospect of installing optomisers on every panel in parralled strings vs just effected one as some partners is a vastly different payback proposition at current prices.

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Mark C said : administrator Report 2 months ago

Hi Craig, It's a good question and one that I have planned to do testing on. I would probably say you are correct. The main issue is we need to keep the voltage same on both strings, and I just don't know if the unshaded string would follow what the shaded string was doing. But, will let you know when we test!

Craig said : Guest Report 3 months ago

Mark, could you elaborate on the situation for using these with strings paralleled? Is it possible to still selectively deploy them to panels which are impacted by shading or is it required to deploy to all panels? If selective deployment is not possible, would it be possible instead to say selectively deploy to the same number of panels on each string which is paralleled?

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Mark C said : administrator Report 5 months ago

Hi Mark, Yeh that would work, the single string of 10 can have a selective deployment. I'm not sure what the deal is with the SMA optimiser - I guess it is just a rebranded Tigo. SMA are part owners and the importer of Tigo into Australia, so I guess they have not rebranded it here.

Mark S. said : Guest Report 5 months ago

Hi Mark Thanks so much for the advise. Just for clarification, The best way is to put the East and the West panels on one string and an optimiser for each panel. Then put the North panels on the second string, and connecting optimisers to those panels that will have partial shading? Mark P.S. looking at the SMA videos, it seems to me those SMA optimisers are VERY VERY similar to the Tigo optimisers (if not identical). They even have the same name (TS4-xxx).

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Mark C said : administrator Report 5 months ago

Hi Mark, Thanks! Don't use 2 inverters and Don't go a Fronius symo hybrid (it is outdated). Just go with a Fronius symo, and there will be a retrofit battery solution later. If the shade is between 9 am and 3 pm, I would probably optimise every panel with Tigo. Partly because you will need to parallel the 6+6, so you need to optimise every panel when in parallel. It will cost more than SolarEdge, but don't even consider SolarEdge. Tigo is leagues ahead. Hope that helped, or reply and I'll help clear it up.

Mark said : Guest Report 5 months ago

Hi Mark Very nice article, and I am really enjoying your blog, and the technical background. Thank's a lot for those. I want to install solar on three sides of my house - 6 panels east, 10 panels north and 6 west. (=22x300w= 6.6kW). North and west have some wandering shading, and also with 3 different sides, I need some sort of panel optimising. With 6 panels each on West and East a SolarEdge system would work and but after reading your blog I am leaning towards a combination of Fronius Symo Hybrid with a Tigo optimiser. Would a Tigo optimiser hocking the West and East panels together allowing for the East to produce in the morning and the West for the afternoon? Or should I rather look for two seperate inverters allowing a total of 4 strings? Advise much appreciated, Mark

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Mark C said : administrator Report 5 months ago

Hey Scott, thanks for your comments! Tell me if I've missed the point, (you knowledge of inverters is lightyears ahead of mine) but the problem with optiTrack (SMA) and Dynamic Peak Manager (Fronius), is it forces bypass diodes to engage. This is good for production, but not good for panel bypass diodes. Diodes were not designed to be activating so often. LG highlights shaded panels as warranty issue as I mentioned in the in the post and Gmmpt exacerbates the problem. So a big reason for Optimisers is to protect your bypass diode. It also allows a bit of production from a panel that optitrack would have otherwise forced into bypass. .... Thanks for the links. SMA optimisers?! - I'll need to look into that!!

Mark C said : administrator Report 5 months ago

Hi Raymond. I think Tigo will help in this situation, assuming the panels are not always evenly shaded. At the time of the shade illustrated in your picture, the diodes will engage, but it will not engage as often as it otherwise would have.

Scott Partlin said : Guest Report 5 months ago

Mark, A nice blog and some very thorough research. Firstly, a declared interest from me. I work at SMA, and SMA have a financial interest in Tigo, and SMA sell Tigo units in Australia. I would add a few things in relation to partial shade. For partial shade, MLPE (like Tigo TS4-R-O, SolarEdge, Enphase, etc) is NOT ALWAYS necessary. Most modern solar inverters (from all manufacturers, SMA, Fronius, Zeversolar, etc) have a global maximum power point tracking (GMPPT) function which, typically, return at least half of energy lost due to shade when compared to MLPE. By this I mean, if partial shade caused your production to drop from 100% to 80%, a GMPPT would return that power to ~90%, while MLPE would return that power to between 93-95%. I discuss that in an SMA blog here: The way a GMPPT works is essentially by changing the voltage to turn on ALL of the BYPASS DIODES in the SHADE-AFFECTED modules. This video (sorry, it's an SMA video) provides a good "customer explanation" of how it works. The SMA OTGP referred to is a GMPPT function. (here is the version for an Engineer hehehe There is also another video (again, sorry it's an SMA video) which explains for a "customer" how the Tigo TS4-R optimisers work Again, nice blog. Just wanted to add some extra info. Keep up the good work MarkC

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Mark C said : administrator Report 5 months ago

Hi Hans, I'm not sure what you mean. My testing showed the Tigo usually meant that the bypass diode did not have to engage as soon as others.

Raymond said : Guest Report 6 months ago

I am about to install a Tigo based system on my roof. It wil be a landscape oriented panels with lot's of horizontal shadow during the winter. How does Tigo handle that? Installer #1 advised Tigo, which sounds good. Installer #2 sees problems in landscape oriented and horizontal shadow and the risk over bypass diode overheating. What happens when 1 or 2 diodes are activated in a panel? See picture for my shadow situation.

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Mark C said : administrator Report 6 months ago

Hi Dan, that sounds right, although Tigo is considered an MPPT device too. It just operates differently from SolarEdge. The problem I have with Maxim is that they have so far only dealt with cheap panels. I'm looking into the new (entry-level) Suntech-Maxim option as soon as I can get them. Unfortunately quality panels like Qcells, Sunpower or LG are not integrating Maxim yet.

Dan said : Guest Report 6 months ago

Let's see if I understand this correctly: * Micro Inverters: Panel-level MPPT, AC output * SolarEdge: Panel-level MPPT * Tigo: Panel-level enhanced bypassing * Maxim: Cell-string-level enhanced bypassing Is this correct? Dan.

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Hans Leijsen said : Guest Report 6 months ago

Hi Mark, Excellent article. One correction: when a panel is partially shaded (1 or 2 cell strings shaded) every optimizer will force the bypass diodes to engage. Maxim technology seems to me the best solution to tackle shade.

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Mark C said : administrator Report 6 months ago

Hi Paul, Yes Tigo allows every panel to work at their maximum. That test would be interesting. Because I think both products are really only needed in shade (or split orientations) the comparison that I find more useful is how they respond in shade. I think I've proven through previous tests (not side by side), that Tigo often responds better in the shade. SolarEdge has a significant problem with blocking, and the fixed string voltage means that it needs at least 5 panels unbypassed to operate. Also, Tigo has proven to be significantly more reliable. (Have a read of my latest SolarEdge blogs. )

Paul2 said : Guest Report 6 months ago

Does the Tigo TS4-O allow each panel to output its maximum power - like the SolarEdge optimisers do? If The Tigo TS4-O does, I think it would be really interesting to see which system yeilds the most AC power out. I.e. a 10 panel Solaredge HD Wave system vs Fronius Primo 10 panel system with TS4-O’s. There are a couple of things I think should be done to ensure the accuracy of the tests. 1. The number of panels really doesn’t matter so long as both systems have identical: model, number (quantity) and age of panels. 2. Same sized inverters are used on both systems. 3. Particular care taken to ensure the Fronius inverter is being run in its optimum efficiency window - this can be easily worked out from the efficiency data included on its specification sheet - as I remember that big discovery during the maxim panel tests!). 4. Appropriately sized Solaredge optimisers are selected to ensure they are operating at their optimum efficiency, I.e don’t use a P500 optimiser on a 250w panel. (See Solaredge’s “application_note_optimizer_effeciency.pdf”. 5. Ensure each set of panels performs equally, given the +- tolerances of panels. (This could be achieved by first testing all panels with optimisers, to ensure each set achieves the exact same total energy for a given period). 6. You could even add a non-optimised system so it can be directly compared to the optimised systems, to show how much less (or more) power it produces under “no shade” conditions. - I don’t know about anyone else but I would definitely find the above test super interesting an informative, especially if results were given for: perfectly fine day, patchy cloudy day, overcast day, week and a month.

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Paul said : Guest Report 6 months ago

Another truly excellent article, super informative as always - thanks Mark. I particularly found the testing to see when the bypass diodes kicked in (and when they didn't) very interesting. 5 recorded failures (warranty claims) for the TS4 optimiser in Australia!! I'd pretty much say that qualifies the TS4 optimiser as basically bullet proof (even if the actual failure rate higher than that).

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Mark C said : administrator Report 6 months ago

Hi Phillip, Thanks. Personally, if you don't have shading, I wouldn't use any type of optimiser. I think the small benefits you get are outweighed by reliability issues.(Unless of course, you want "rapid shutdown" for safety.) A monitored string inverter will also pick up if you have a significant problem with a panel.

Sven Klavsjo said : Guest Report 6 months ago

Hello Mark, thank you very much for an excellent review of TIGO. It is probably leaving anything looked into, and shows it is most likely the absolutely best optimizing solution available today. The basic idea not to really care about what is hiding in the black box is really showing good results. Have you tested what effect a large leaf landing on the panel almost blocking a whole cell would have, this might lead to a hot-spot. A quick look at the TIGO Junction Box Version for integrated TIGO panels, gives you the idea that a future version of TiGO might be able to optimize cell-string by cell-string like the Maxim solution, all four connections seems to be in the junction box, but maybe I'm wrong there. You are absolutely right about that the more components the worse reliability, increasing operating temperature will do the same. Have the Tigo module a plastic or metal cover, from the pictures I have seen it is not possible to determine that A metal cover might reduce internal temperature, and plastic seems to disintegrate after ten years in Thailand sun unless the the surface oxidize and make a UV-protective cover. I think it would be nice if TIGO stated if they mean maximum ambient temperature when they state operating temperature or if it is temperature near the TIGO box. Since I'm looking to have bi-facial panels mounted vertically in landscape mode east-west, optimizing cell-string by cell-string would make it possible to put the rows closer to each other. Vertical panels will have a large wind load so I will not mount them on top of each other, and with a 30-50cm gap to the roof under the panels to reduce wind pressure. Hopefully it will not be necessary with some kind of spring solution like the one on advertising boards om the pavement, that withstands strong wind gusts. Sven

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Vladimir said : Guest Report 6 months ago

Hi What about the safety? For example to set low output voltage in case of emergency How does Tigo optimizer handle this? When you selectively deployed the optimizer - not each panel has optimizer - you cannot ensure low output voltage. What is an efficiency of the Tigo optimizers compered to Solaredge and Huawei? Thanks

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Philip said : Guest Report 6 months ago

A very well researched and executed set of tests Mark - you do the industry proud. I've had many an installer try to push me into using SolarEdge systems without mentioning that that would mandate the use of their Inverter only. Like you, I am all for the fewer electronic components on the roof the better - the cost of a service call to replace an optimiser will more often that not exceed that of the optimiser itself. In our installation, we have NO shading issues at any time, so the use of optimisers really would only come into play when a panel is faulty I would think. Do you have any further insights or comments on that? I am thinking here of early morning and late afternoon sunlight. Could optimsers extend the output from the panels at these times through impedance correction? The string outputs will be fed into a Fronius 20KW inverter. Regards, Phil.

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