Tiago optimizers or not? Please read below

[Strousy]

Hello Hakan Thn,
my thoughts: Yes you are correct this does not appear right. It fits exactly with my own and Mark Cavanagh's findings. What should happen is that the currents in the two strings are similar - in principle - all the time. If the optimisers would work, the current produced by the panels in full sunshine would be passed on to the sting input of the inverter while the voltage and current (Power (W) = Voltage (V) x Current (I)) of the panels in partial or full shade providing less power is converted into a lower voltage but a current that matches the other panels. The correct effect of an Optimiser would be to maximise the current bringing it to the level of the other sunny panels. This would stop the shaded panels from impeding the energy for the sunny panels to be utilised while adding perhaps a little energy to the total still. Like Mark Cavanagh, I believe the problem to be enormous and Tigo maintains the confusion while profiting, not unlike Big Tobacco.

 

[Strousy]

Not sure why all the hate towards Tigo — I’m a fan. Even those panels not directly shaded can benefit from installing optimizers. Also, it is incredibly valuable to be able to “see” what each panel and each string is doing in terms of power, voltage, amps, etc. at any moment in time. I learn a lot more from my Tigo app (panel-centric) than my OpticsRE app (inverter-centric).

There appears to be a big difference between Tigos hooked up to the Tigo monitoring system and Tigos not hooked up to such a system. It is the latter that from at least 3 reports now do not operate like promised.

 

[wattmatters]

I have a solar system installed in May this year, and believe I might have faulty Tigo optimizers. Would like to have your view on this.

Are the Tigos standalone or are they connected to central controller?

 

[Strousy]

Are the Tigos standalone or are they connected to central controller?

My Tigos are standalone, it would appear that systems connected to a central monitoring system do get a software update through the internet which aparently fixes the issue of not working as promised in the sales blurb.

 

[HakanThn]

Are the Tigos standalone or are they connected to central controller?

My Tigo are also standalone. I have a deal with the installer to borrow a controller free of charge to see if it helps to connect one. Problem is they do not have any in stock, and delivery time could be 6 months or more.

 

[wattmatters]

My Tigos are standalone, it would appear that systems connected to a central monitoring system do get a software update through the internet which aparently fixes the issue of not working as promised in the sales blurb.

I'd rip them out and demand a full refund. False advertising.

 

[HakanThn]

Hello Hakan Thn,
my thoughts: Yes you are correct this does not appear right. It fits exactly with my own and Mark Cavanagh's findings. What should happen is that the currents in the two strings are similar - in principle - all the time. If the optimisers would work, the current produced by the panels in full sunshine would be passed on to the sting input of the inverter while the voltage and current (Power (W) = Voltage (V) x Current (I)) of the panels in partial or full shade providing less power is converted into a lower voltage but a current that matches the other panels. The correct effect of an Optimiser would be to maximise the current bringing it to the level of the other sunny panels. This would stop the shaded panels from impeding the energy for the sunny panels to be utilised while adding perhaps a little energy to the total still. Like Mark Cavanagh, I believe the problem to be enormous and Tigo maintains the confusion while profiting, not unlike Big Tobacco.

Thanks for your reply, I fully agree with you.

 

[HakanThn]

I'd rip them out and demand a full refund. False advertising.

Yes, the installer has offered to come and remove them (refund not discussed yet). I would most probably be better off without them then having them not functioning as it is now.
I believe though that optimizers working as intended would give some benefit in my installation. Will try to make a theoretical power calculation later today and post for feedback.

I'm also interested in this subject from a learning perspective, and maybe helping others. Like Strousy writes, this could be a problem that many has without knowing it. It is difficult to identify the problem, and I believe many installer companys to not fully understand it. The initial response from my installer when I showed him the current graph was "This is normal! The 50% current period is the Tigos operating, without them you would have had zero current all the time until fully in sunshine". I took me a while to gather enough evidence to convince him to do something about my system, but I think he still don't believe this to be a bigger problem.
Adding to this: My neighbour installed exactly the same solar system on a twin house the at same time I did, and he has the same behaviour in his system.

A side story explaining my interest a bit: I had a problem with a newly installed solar panel on my boat three years ago - only half the panel was working. I managed to identify and prove the problem by alternatively cover 50% of the panel and measure the current. It took a video of such test to convince the seller to refund me.... Later the same year, before I hade replaced the panel, a boat neighbour in a guest harbour approached me "We have the same solar panel. Are you happy with yours? I don't seem to get as much energy as I was expecting". Turns out he problably had the same faulty panel as I did, but didn't know how to check the panel. Either an odd coincidence, or the panel manufacturer had been pumping out faulty panels without noticing it.

 

[Strousy]

Yes, the installer has offered to come and remove them (refund not discussed yet). I would most probably be better off without them then having them not functioning as it is now.
I believe though that optimizers working as intended would give some benefit in my installation. Will try to make a theoretical power calculation later today and post for feedback.

I'm also interested in this subject from a learning perspective, and maybe helping others. Like Strousy writes, this could be a problem that many has without knowing it. It is difficult to identify the problem, and I believe many installer companys to not fully understand it. The initial response from my installer when I showed him the current graph was "This is normal! The 50% current period is the Tigos operating, without them you would have had zero current all the time until fully in sunshine". I took me a while to gather enough evidence to convince him to do something about my system, but I think he still don't believe this to be a bigger problem.
Adding to this: My neighbour installed exactly the same solar system on a twin house the at same time I did, and he has the same behaviour in his system.

A side story explaining my interest a bit: I had a problem with a newly installed solar panel on my boat three years ago - only half the panel was working. I managed to identify and prove the problem by alternatively cover 50% of the panel and measure the current. It took a video of such test to convince the seller to refund me.... Later the same year, before I hade replaced the panel, a boat neighbour in a guest harbour approached me "We have the same solar panel. Are you happy with yours? I don't seem to get as much energy as I was expecting". Turns out he problably had the same faulty panel as I did, but didn't know how to check the panel. Either an odd coincidence, or the panel manufacturer had been pumping out faulty panels without noticing it.

It is frustrating when optimisers do not operate as advertised. I agree that many installers do not fully understand what they are selling. This is analogous to western "doctors in medicine" not fully understanding the basics of health limiting their efficacy as health profesionals.
Re: "This is normal! The 50% current period is the Tigos operating, without them you would have had zero current all the time until fully in sunshine" if the Tigos were working, the voltage would drop reflecting the effect of the shade on power potential, but the current would remain similar allowing the sunny panels in the same string to continue to pass on all their power to the inverter. It is the effect on the current by the shaded panels that creates the issue of the "kink in the hose".
Re: "alternatively cover 50% of the panel" - you have an analytical mind changing perspectives in order to understand, great to see!

 

[Strousy]

By the way HakanThn, a quality modern inverter with global max power tracking like Fronius, utilising the by-pass diodes in the panels, can outperform operating optimisers under shaded conditions.

 

[HakanThn]

I've tried to make some theoretical and simplified calculations of power output from my system in different shade situations, with bypass diodes, with working optimizers and compared to current situation. It seems I could benefit from working optimizers. Grateful for any feedback on calculations and practical experience!

The shade is moving almost as a straight vertical line across the panels. As I have half-cut panels, there will be 5 distinct sun cases, from case A=4 panels in full sun to case A-E=all 12 panels in full sun. See photo.


Summary of results:

	A​	A-B​	A – C​	A-D​	A-E​
Only Diodes	0​	1240W​	2560W​	1920 or 2560W​	3840W​
OK Optimizers	1400W?​	1920W​	2610W​	3200W​	3840W​
Today	0​	0​	0​	1920W​	3840W​

Calculation assumptions and details:

System specs:

• The shaded string has 12 panels in series, placed in 3 rows of 4 panels, Panels Eurener MEPV 410, 120 cells half-cut, Bypass diodes in 3/6, Vmpp about 32V at 800W/m2.
• 8 Tigo TS4-A-O optimizers connected to the 8 mostly shaded panels.
• Growatt MOD 10KTL3-XH inverter, minimum MPPT voltage 140V.

Assume full voltage=32V and full current=10A.
Assume perfect optimizing. Read somewhere that Tigo can optimize voltage only up to 33%, but do not know if true / how that works.

Case A in sun:
Only bypass diodes: Will not reach above the 140V minimum voltage. 4x32 minus diode drop 8x3x0,6 = 114V. No power.
With optimizer: Could maybe operate? Measured current when system is in shade is about 0,4 A, meaning 8x32x0,4 = 102W from 8 panels. That could give 10V at 10A, possibly bringing the total string voltage above the 140V threshold at 10A. 4x32V + 10V = 138V. Power 140Vx10A = 1400W.

A-B in sun:
Only bypass diodes: Half-cut cells give half current but full voltage => U=8x32=248 and I=10/2 = 5A. Power = 1240W
With optimizer: Optimizes half shaded cells to 16V and 10A. String total U=4x32+4x16=192W, I=10A, Power=1920W

A-C in sun:
Optimizers have no or very little effect, potentially +50W from panels in shade.

A-D in sun:
Bypass diodes: Half current from half cut cells => 12x32V and 5A = 1920W. Alternatively fully bypassed panels => 8x32V and 10A = 2560W
Optimizers: 8x32+4x16V, 10A = 3200W.

 

[wattmatters]

Unless you get your Tigo central controller happening, I'd just remove them.
Strike that, see below.

System specs:

• 12 panels in 3 x 4 arrangement

OK, this changes things. A lot.

I thought you just had a single string because earlier you said this:

My installation has two strings with 16 and 12 panels respectively.

I was always under the impression that with strings in parallel you can't partially deploy Tigos to just some panels.

When you have parallel arrays Tigos either need to be on all panels or on none of them.

When running a single string into an MPPT then yes you can selectively apply Tigos to some panels.

You've been sold a pup and your installer doesn't know what they are doing. I strongly suggest contacting Tigo directly for some support because your installer is screwing you. They may not be doing it deliberately but they are costing you time and money because of their wilful ignorance.

In the meantime, unless you plan to add Tigos to the remaining panels AND add the central controller (and I wouldn't), then I would pull the Tigos all off and leave the arrays and MPPT to sort themselves out. The fact you have 3 small arrays in parallel AND they are half cut cells will be plenty good enough IMO to provide decent production during that period of the day when the array is partially shaded.

 

[wattmatters]

See Tigo's own documentation:

https://support.tigoenergy.com/hc/en-us/articles/4618530325139-TS4-Systems-Partial-Deployment

Design Guidelines​

Rule: Partial deployment should only be used when a string has its own MPPT and is actively independent of any other string. Partial deployment of optimization on parallel strings is NOT supported.

 

[Strousy]

@HakanThn Have you read: https://www.mcelectrical.com.au/tigo-energy-solar-panel-optimisers/ ? Mark Cavanagh produced this before his cry for Tigo recall: https://www.mcelectrical.com.au/tigo-optimiser-recall/
If you have a Tigo monitoring system, they might be OK but you judge the story and experiments of Mark.

 

[HakanThn]

Unless you get your Tigo central controller happening, I'd just remove them.
Strike that, see below.



OK, this changes things. A lot.

I thought you just had a single string because earlier you said this:

I'm very sorry for causing confusion - all the 12 panels in this string are actually in series configuration. I wrote "3x4 arrangement" only to describe the placement of the panels on the roof. I have edited my post, hope it is more clear now. Many thanks for trying to help me!!

 

[Strousy]

How do you know if your Tigos are working correctly?