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Microinverters vs string inverters

 
Solar Photovoltaic (PV)
Last Post by nickk 3 years ago
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 MattEngineer
(@mattengineer)
Trusted Member Member
Joined: 4 years ago
Posts: 50
Topic starter 28/10/2021 1:49 pm  

I’m putting the ASHP on the back burner and looking at solar on a South West facing roof. I appreciate the benefits I.e. single point of failure and individual panels being optimised but for the additional cost wouldn’t it be better to upgrade from 340w panels to 400 watt panels which are half the cost of enphase microinverters. 

I would welcome the views of those who have a single string inverter and microinverters in terms of your reasons for selection. 



   
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 batalto
(@batalto)
Noble Member Member
Joined: 5 years ago
Posts: 1092
29/10/2021 6:20 am  

I didn't bother with micro and went with string. There is no shading on the roof and the price of micro Vs the percentage gain didn't make it worth it for us. Payback period was far too long


12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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 Ken Bone
(@ken)
Trusted Member Contributor
Joined: 5 years ago
Posts: 21
01/11/2021 11:03 am  

Not sure if this is specific to the string inverter used or more general to modern equipment but I found this interesting from NRG Solar in Australia



   
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 MattEngineer
(@mattengineer)
Trusted Member Member
Joined: 4 years ago
Posts: 50
Topic starter 02/11/2021 3:25 pm  

@ken 

Great video thanks for posting, just my kind of testing I.e real life

Decision made



   
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 Ken Bone
(@ken)
Trusted Member Contributor
Joined: 5 years ago
Posts: 21
04/11/2021 10:15 am  

We have two string running to a Ginlong Model 8D inverter (which is quite old now) here you can see some shading and it's impact on generation... Exactly why I got the EmonPi to see what impact the winter shading was having on the generation. Don't know what a new inverter would do for us.

Someone tried to sell us a Solar Edge inverter without even looking at what we had... I was wanting to talk to them about a new ground mount system but never got a chance to even ask about that so sales lost out there...

EmonPi Shade
shade

 



   
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 SKD
(@skd)
Trusted Member Member
Joined: 4 years ago
Posts: 63
08/11/2022 7:22 pm  

@ken I've been looking into a string inverter for two new roof arrays with some slight intermittent shading.  I also found this video to be really informative, and encouraging.  I would like to avoid optimisers etc up on the roof if at all possible.

The video demo used a Fronius Primo inverter, which uses something called Dynamic Peak Manager.  Looking it up it seems to be their version of Global MPPT.  

I've been trying to establish how commonplace Global MPPT is in today's solar inverters, as it seems to be a notable benefit when operating a shaded string.  For example, I contacted Givenergy about their inverters but the tech support team didn't have any information beyond their datasheet.

Any opinions at all would be greatly appreciated. 🙂 

 


Mitsubishi Ecodan 11.2kW R32 ASHP; Ecodan DHW cylinder; UFH+rads
20x430W Jinko TOPCON Tiger Neo solar; Luxpower 6+4kW hybrid inverter; 20kWh Hanchu ESS LFP battery storage
PHEV; Zappi charger
1997 stone detached house with updated insulation. 140sqm, maintained at 20-22degC 24/7


   
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 squeakysim
(@squeakysim)
Trusted Member Member
Joined: 3 years ago
Posts: 50
16/11/2022 7:55 am  

That was a gret little demonstration is that vid.

I did a bit more searching to try and find out why that is and this vid came up and to me helped explain very clearly in pretty straight forward terms what is going on with shading

Assuming this is accurate, it seems the simplest summary (anyone feel free to correct me if I'm wrong!) is that optimisers and microinverters are great for maximising output when the shading is diffused and there is essentially still some light reaching all of the cells on the panel (distant tree or cloudy inclement weather) or there's a small shadow (e.g. cable across a panel), but when the shading is heavy and blocking out a cell or more, there's no real difference as was demonstrated in the NRG video.



   
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KoRWraith
 KoRWraith
(@korwraith)
Estimable Member Member
Joined: 3 years ago
Posts: 62
17/11/2022 2:20 pm  

I agree with your summary, which was very surprising to me as I was always under the impression that the heavier the shading the greater the case for microinverters/optimisers!



   
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 nickk
(@nickk)
New Member Member
Joined: 3 years ago
Posts: 1
09/07/2023 11:32 pm  

Posted by: @skd
↑

@ken I've been looking into a string inverter for two new roof arrays with some slight intermittent shading.  I also found this video to be really informative, and encouraging.  I would like to avoid optimisers etc up on the roof if at all possible.

The video demo used a Fronius Primo inverter, which uses something called Dynamic Peak Manager.  Looking it up it seems to be their version of Global MPPT.  

I've been trying to establish how commonplace Global MPPT is in today's solar inverters, as it seems to be a notable benefit when operating a shaded string.  For example, I contacted Givenergy about their inverters but the tech support team didn't have any information beyond their datasheet.

Any opinions at all would be greatly appreciated. 🙂 

 

@skd did you find any information on Global MPPT?  I'm particularly interested in whether GivEnergy's inverters have it (not had a sensible answer from the Facebook GivEnergy forum ;-(

 



   
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