Without knowing your panel's power, difficult to say, but for comparison we managed a tad under 40kWh in sunny east anglia this month with 16, 410W panels on E-W configuration.
Unusual Generation in the Morning
- Thread starter BaldDave
- Start date
I'm struggling to understand your point. You seem to be suggesting just one optimiser for 12 panels?? Which panel would you attach it to?
robbob2112
Doing more research, mosty harmless
I would like to ask for on-topic clclarification.
I was under the impression you could combine multiple strings to a single mppt input. So long as not exceeding its current and voltage specs.
The example I have for that is 2 strings west. Then a string south on a different mppt. Then an east on a different mppt.
I am curious about what would happen if you tried to combine an east and west string in a combiner box then connected that to a single mppt?
I suspect it is a bad idea, but haven't got it firm in my head.
So 50% more would be around 60KWh….13% better.
timselectric
If I can do it, you can do it.
- Joined
- Feb 5, 2022
- Messages
- 19,853
That's fine.
They are different strings.
timselectric
If I can do it, you can do it.
- Joined
- Feb 5, 2022
- Messages
- 19,853
The issue here is that the installer put in a single string with panels facing different directions. And tried to compensate for the bad design with optimizers (at the customers expense).
I would consider this installer a scammer.
I would consider this installer a scammer.
My brain hurts!
You quoted them take that to mean complete drop off of the string that contains the "heavily shaded PV-Modules"; I could be wrong, but if they didn't mean that, all they are saying is that heavily shaded panels won't produce power (which is kind of obvious).
I thought it meant those 6 wouldn’t produce power BUT would not stop the others producing.
Never-the-less, their own example is a strong point. Would be worse for east/west.
To get round this, my installer will need to provide data showing other east west single strings suitably optimised work.
robbob2112
Doing more research, mosty harmless
lemme take a stab at this
The problem is if east is wired in series with west the weakest panel is your limit - so all the current in series has to route through all panels. In that setup in the morning your east panels have power and your west don't. So the optimizers on the west panels bypass them. The problem is just the east panel may not exceed the start voltage of the MPPT. So they start producing later when they are in full sun verse partial sun as it rises. Then in the afternoon they reverse and the west panels produce and the east panels don't. So you cut off early in the afternoon and loose that light.
Now the rub comes if neither set can exceed that start voltage on the MPPT you won't get any power out of it all day long.
It would have been cheaper by far to add a MPPT to the system instead of trying to make up for the situation with optimizers that may not ever let you produce.
Mixing panel sizes and wattages causes all sorts of problem - same issue - in series the current has to flow through all panels and if one panel is rated for 30 amps and another is rated at 10 amps then all panels can only push 10 amps.
Thanks
I don’t know very much about MPPTs. But I do know that when the east 6 are not producing much, around 20W total before around 8am even in bright sun the voltage is above 300V. Plenty high enough.
Also, when the sun is lower than the apex of the roof putting the east 6 in the shade of the roof - the west 6 are not stymied and can still produce 2000W (the other string of just 12 west producing around 4000W) giving the system a total of 6000W
It’s just an early morning problem!
All the panels are the same, max 405W. I don’t know the amps.
I hear what you are saying, but as several of us have told you, they are not designed to work in that configuration. Your installer has messed up.
It is just how optimisers work - they can even out small differences, but not when half your panels are facing the USA and the other half facing China.
Please read through this other thread from a UK poster who had same issue as you did, who we helped resolve this issue by urging him to have his system reconfigured.
diysolarforum.com
It is just how optimisers work - they can even out small differences, but not when half your panels are facing the USA and the other half facing China.
Please read through this other thread from a UK poster who had same issue as you did, who we helped resolve this issue by urging him to have his system reconfigured.
Tigo Optimisers on a string with 2 orientations not optimising as hoped
My Tigo TS4-O optimisers on one of my strings is not behaving as I would expect and would like a second opinion on what Tigo support have left me with please. On clear sunny days, my panels are massively underperforming and I can't find a good reason why. Tigo support have humoured me with many...
diysolarforum.com
Last edited:
I will. Thank you.I hear what you are saying, but as several of us have told you, they are not designed to work in that configuration. Your installer has messed up.
It is just how optimisers work - they can even out small differences, but not when half your panels are facing the USA and the other half facing China.
Please read through this other thread from a UK poster who had same issue as you did, who we helped resolve this issue by urging him to have his system reconfigured.
Tigo Optimisers on a string with 2 orientations not optimising as hoped
My Tigo TS4-O optimisers on one of my strings is not behaving as I would expect and would like a second opinion on what Tigo support have left me with please. On clear sunny days, my panels are massively underperforming and I can't find a good reason why. Tigo support have humoured me with many...
shadowmaker
Solar Addict
Or just plain stupid.
teal95
Solar Addict
My understanding of the optimizers is that they use a buck convertor to take the energy a panel is producing and reduce the voltage until the current matches what the rest of the string is producing. Is it possible that with most of the string facing west the few panels facing east that the voltage isn't high enough to meet the minimum for the SCC to start?
Sergio95050
New Member
There is a point what is unknown to me - the optimizers must be controlled from an inverter by some way, because I'm getting data from the parts independently (by telemetry) and Vdc on the string is stay at one level ~350VDC all the time. From early morning, during the day, exclude clipping time midday.
So right now at 06:40, my string with 12 west facing is generating 250W at around 350V and my east west split string is generating 20W at around 420V
Hahahahaha. I thought AFAIAA was a technical expression for a type of optimiser! Now, AFAIAA I know it’s not!
Thank you for all your knowledge. I’m away from home for a while but will find out the details of my Inverter etc .
My LuxPower Data History read out has about 50 Columns, many of those have a Voltage. Most of the columns I have no clue about, but I could export the data to a file and attach it to this thread. I’ll look into what that web monitor says about configuration too.
You all asked what my inverter is. I’ve just got home and looked in the loft. It’s a LuxPower. LXP-6K Hybrid. According to the info plate on it, it has 8000W max DC power. MPPT voltage range of 120 to 500V.
I guess the 8000 is split between PV1 and PV2….4000/4000 but that might not be true…as PV1 is often above 4000 and has peaked at 4900 (12 panels of 405) The user manual online says it’s 4000/4000
The export is often just above 6000 on sunny days, best ever 6111 AFAIAA. Best ever yield around 6500.
The MPPT (s) has never been outside its voltage range.
So I think that because of the limits of the string power, the only solution is either
1) Get a 3 string hybrid and split 9,9,6 OR
2) Get an additional inverter to work in parallel with current one (pun intended) and split 9,9,6
Do you see any other answers?
The installers are actually nice people …just not right on this occasion. They have the best recommendations.
I guess the 8000 is split between PV1 and PV2….4000/4000 but that might not be true…as PV1 is often above 4000 and has peaked at 4900 (12 panels of 405) The user manual online says it’s 4000/4000
The export is often just above 6000 on sunny days, best ever 6111 AFAIAA. Best ever yield around 6500.
The MPPT (s) has never been outside its voltage range.
So I think that because of the limits of the string power, the only solution is either
1) Get a 3 string hybrid and split 9,9,6 OR
2) Get an additional inverter to work in parallel with current one (pun intended) and split 9,9,6
Do you see any other answers?
The installers are actually nice people …just not right on this occasion. They have the best recommendations.
I'll add my input here too for completeness..
18 on one string is not possible due to exceeding Voc.
Two parallel strings of 9 is not possible due to max current on inverter
Option (1) would be expensive.
Option (2) could be possible, though not ideal and what would ROI be?
Datasheet for that inverter says max input voltage of 550V, so that's one you'll need to watch if your changing string configurations. Use (Voc of panel) x (number of panels in string) x 1.1 to account for 10% higher voltage when about -15C, assuming your panels have standard(ish) -0.25% voltage increase per degree C.
Not immediately, will put my thinking hat on.
18 on one string is not possible due to exceeding Voc.
Two parallel strings of 9 is not possible due to max current on inverter
Option (1) would be expensive.
Option (2) could be possible, though not ideal and what would ROI be?
ROI:
I estimate the loss of production over a year will be around 1000KWh. So about £150 loss of export value + cost avoided by using Solar rather than grid. Can’t calculate that very well as we already generate more than we use.
Value: learning experience for the installer?
String Power
The Inverter Data Sheet says it’s 4000 W per string….but PV1 frequently goes to 4400 on sunny days, peak of around 4900 on sunny days (more than the 12*405). How is that?
PS optimiser manufacturer emailed to say “East West single string NOT recommended “ as all have told me on this thread. Thank You.
I suspect they are guideline figures. The inverter says it can support up to 8000W input; and 6000W AC output - so the spare will be used to charge batteries. The only unfortunate limit I see with that inverter is the max of 80A / 4000W for battery charge/discharge.
Then armed with that info (as well as our input) would be a good reason to negotiate a "fix-it-for-free" with your installer. It may come down with what they proposed and quoted for, but I guess, as a Yorkshireman you'll be able to negotiate a resolution so you won't be out of pocket
Do keep us posted.
Will doI suspect they are guideline figures. The inverter says it can support up to 8000W input; and 6000W AC output - so the spare will be used to charge batteries. The only unfortunate limit I see with that inverter is the max of 80A / 4000W for battery charge/discharge.
Then armed with that info (as well as our input) would be a good reason to negotiate a "fix-it-for-free" with your installer. It may come down with what they proposed and quoted for, but I guess, as a Yorkshireman you'll be able to negotiate a resolution so you won't be out of pocket
Do keep us posted.
Dear All
Just had the installer round for a chat.
He has offered to put in a three string inverter and do a new G99 (possibly for more export permission too) for free.
We offered to pay the difference to the bigger inverter but he wants to do it for free.
He also said that councils are starting to put in East/West single strings with optimisers.
Many thanks for your knowledgeable input…and update when the work is done.
Just had the installer round for a chat.
He has offered to put in a three string inverter and do a new G99 (possibly for more export permission too) for free.
We offered to pay the difference to the bigger inverter but he wants to do it for free.
He also said that councils are starting to put in East/West single strings with optimisers.
Many thanks for your knowledgeable input…and update when the work is done.
timselectric
If I can do it, you can do it.
- Joined
- Feb 5, 2022
- Messages
- 19,853
One last thing. Is it worth keeping the optimisers on the West roof and moving the East optimisers to it as well? Here’s the shadow detail:
In March and April, when generation amounts have risen the West side gets a 60cm wide chimney shadow from the neighbour. (Our roof is the same height as the neighbours, the apexes about ten metres apart. ) Probably August September too. May June July, that shadow has moved round before it creeps up to the solar panels - and misses them.
There are no other shadows.
I don’t know how much such a shadow, if it goes across one panel reduces the output from a string with 9 405W panels.
I’ve offered to pay for the optimisers if I keep them. Tigo, not wifi connected so about £40 each.
Sorry for such a numpty question.
In March and April, when generation amounts have risen the West side gets a 60cm wide chimney shadow from the neighbour. (Our roof is the same height as the neighbours, the apexes about ten metres apart. ) Probably August September too. May June July, that shadow has moved round before it creeps up to the solar panels - and misses them.
There are no other shadows.
I don’t know how much such a shadow, if it goes across one panel reduces the output from a string with 9 405W panels.
I’ve offered to pay for the optimisers if I keep them. Tigo, not wifi connected so about £40 each.
Sorry for such a numpty question.
CaliSunHarvester
Solar Enthusiast
I asked a similar question in another thread without a clear answer.
Wouldn't the inverter determine how much current it pulls?
If the inverter limits the current, the user could have 2, 3 or 4 strings, and each string would only send very little current?
Similar threads
