Advanced large scale inverter panel configurations

Tuesday, August 3, 2021
Training
by
Veli Markovic

​​Where we left off from last time

As discussed, in our previous presentation, a lot of trial and error is involved when trying to design large commercial solar systems that involve multiple inverters, sometimes with different capacities, same brands though, and in some cases more than one kind of solar panel. 

With smaller systems this trial and error process is just acceptable but does not “cut it” with larger systems.

So previously we took a spreadsheet approach that allowed a certain level of automation to occur and through the process, relevant information could be displayed. 

We looked at the generation of string voltages, signage, warnings if certain parameters were exceeded, DC/AC ratios.

In this presentation we look at the generation of more data that can be used.

Inverter details


In the case above we have:

  • 2 x inverters sizes, a 100 and a 30 kW
  • Both Huawei's
  • Different number of MPPT
  • Same Isc

Panel details

In regards to the solar panels:

  • We have a 445 and a 450 watt option
  • Different Vocmax ratings
  • Same amx series fuse ratings

Panel and inverter: with the lot


All the info is there but.  .  .  .

All the info is there in detail for Inverter no. 1 with panel option selected but we need a summary that acts as its own  report.

We could do this manually but, hey, we are using a spreadsheet so let’s use some of the tools available!

Inverter 1 panel inverter summary

So, we have: 

  • Inverter details
  • Total amount of solar
  • DC/AC ratio
  • Total current, signage
  • Panel brand
  • Wattage
  • No. of panels
  • Number of strings

Obviously all the above info is needed as part of the project going forward but how to extract?


Inverter 1 , brand model and capacity

With Inverter no. and Inverter option no. this can be achieved by extracting from the larger section

But with Inverter Brand, Model and Capacity we look again to one of the lookup functions, in this case being XLOOKUP



We use Xlookup which first looks at the value in D48


This searches for his info in B21:K21


 


Then finds the  corresponding reference in B22:K23.

Now this formula also returns the model number as well as there is a spill


I could have included capacity in the same formula but did it separately

In this case the xlookup referenced the summarized information @ W58

Again, the formula searches in range B21:K21 and returns the capacity value from range B32:K32


Inverter 1 , amount of solar and DC/AC ratio

Amount of solar in kW derived from here.The DC/AC ratio is obtained from the solar divided by the capacity of the inverter.

String with highest VocMax use the Max function in Excel which searches all the strings

In this case they are all the same!

Inverter 1 , Total current

The total current is derived from the number of panels row. 

For example if the number is zero then the SUMIF function does not count the Isc of the panel. 

In this case all are counted.

Inverter 1 , Panel brand

With panel brand we use Xlookup which references the Solar panel option first

Then looks at the range B2:K2  which

Extracts the value from B3:K3.

 

This calculation assumes that different panels will not be used within the one inverter!


Inverter 1 , Wattage, no. of panels and strings

Wattage uses the total then divides by total number of panels

The no. of panels just sums the column heading Wattage of the number of strings uses the countif function and looks at the Number of panels row so if number is not zero it is included ( see below)

One inverter.  .  .  .

If the project only involved one inverter the information shown would enough for:

  • Solar signage, total current being 139.2 amps
  • Solar signage, highest VocMax being 1284.51 Volts
  • Brand, model and number of both inverters and panels, BOM list
  • DC isolators based on number of strings, BOM list

But our particular project involves more than one inverter and more than one panel.


Multiple inverters

In our next presentation we put it all together based on the 2 x different inverter models, 3 x inverters  and 2 x different panels used.

The aim is to design the system, extract all relevant information and the end result can be used in a variety of ways. 

Conclusion

Note: the inverters used have a VocMax of 1500 V and a rated input voltage of 1080 V. Triggers can be used with conditional formatting to show cell colour change if certain parameters are exceeded.

We have barely touched what can be done and in further presentations we will look at yet more advanced techniques which can help the designer installer put together these large scale systems more easily using a spreadsheet approach. 

Look at part 1 if you have missed it: https://www.greenwoodsolutions.com.au/news-posts/large-scale-inverter-panel-configurations

If you’d like to see more of what Greenwood Solutions get up to in the real world of renewable energy, solar, battery storage and grid protection check out the following pages:

https://www.greenwoodsolutions.com.au/industry 

https://www.greenwoodsolutions.com.au/commercial

https://www.greenwoodsolutions.com.au/commercial/customer-stories

https://www.greenwoodsolutions.com.au/news




About the author

Veli Markovic

CEC Designer
Veli has nearly two decades of experience in the renewable industry. He is passionate about providing people with valuable education and is highly regarded throughout the industry as an educator and operator.
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