Commercial Solar on site documentation, part 2

Tuesday, September 7, 2021
Training
by
Veli Markovic

Site specific documentation

In our last presentation we look at some of the documentation that is needed on site to assist in the installation process being fairly painless.

Now we look at specific site install, documentation around:

  • Overall site plan
  • Feet and rail placement
  • Cable string configurations
  • Panel positioning

Assumptions

We are talking about a very large roof where the 500 kW or so of solar barely makes a dent in the available area.

Main component list includes:

  • 5 x 100 kW inverters, 6 x MPPT’s, 2 inputs per tracker
  • Total of 60 strings
  • 400 watt panels x 1380
  • Framing and cable to suit

Let’s get stuck into it!

Birds eye view of the roof, step 1

In this example I used a Nearmap image of the roof, got the correct dimensions and imported it into Autocad.

Correct dimensioning, step 2

Once in autocad the image needs to be dimensioned correctly so the various components can be drawn to the right scale that will show a realistic layout.

This is where the accuracy of the line drawn in NearMaps comes into play.

I have used Autocad but other CAD style programs can be used.

Setting up layers, step 3


Ideally when you draw in Autocad different objects should be placed on different layers.

For example the first layer could be the NearMap image and then layer upon that, like a sponge cake.

Outer perimeter of panel area, step 4

Have drawn the outer perimeter and then used a gradient fill to show where the system goes. Could also put notes into this image as well. Such as the brand , model and number of inverters, framing used, panels brand model and no. and notes concerning inverter and PVDB position.


Overall view of feet and rail layout, step 5

Now we can show the overall layout of the feet and framing with specific differences outlined if there are any. In this case the section on the left is different from the right. 

Overall view of feet and rail layout, step 6

Now we can show the overall layout of the feet and framing with specific differences outlined if there are any. 

In this case the section on the left is different from the right. Also can show the inverter section parts in this case there are 5 x inverters. Also can show the inverter section parts in this case there are 5 x inverters. 

Could also list the amount of framing and feet used. By showing an overall view of the layout allows the installers to understand how it all comes together.

Feet and rail layout, small row, step 9

Now we can drill down a bit and show the dimension of the small rows in the entire framing configuration. For example, it will have 11 panels and 12 panels,  section side by side. Which is different from the other section.

Feet and rail layout, big row, step 9

As with the small rows we do the same with the rows that consist of 23 panels unbroken. Could also add notes that mention the internal cable configurations will be different between the 2 x row types.

Overall view of cable layout, step 11

Another site layout is for the cables and this gives the installers an overview of where they are all going.

Notes could be added showing what actual DC cable is being used and string configurations etc.

  • 4 mm2 and 6mm2 twin used. All strings are 23 x panels each. 
  • Configuration design has tried to minimize differences between positive and negative lengths.
  • Inverters connected to 11 and 12 panel rows have different cable configs compared to inverters connected to unbroken 23 panel rows.

See notes for more details.

Big row cable layout with panels, step 12

This drawing shows the actual panels in situ on the unbroken 23 panel rows. The blue dots signify the first and last panels in the string. Notes can be added to point out the cable run.

Cable layout with panels, step 14

Showing the panels in relation to the cable really helps visually and reduce mistakes made in the installation process. Notes can be added concerning cable tray cable loading maximums.

Cables to be consolidated here where the cable tray is positioned: note max of 28 x DC cables in 150 mm tray due to derating factor. All parallel strings in 6 mm2 minimum: see notes for details.

Cable layout with framing, step 15

The overall layout showing frame and feet is also a good place to outlines some general notes such as: showing inter row cable runs and cable tray requirements

Conclusion

The examples given above are just the tip of the iceberg. At the end of the day site documentation is there to help all the processes flow. Attention should be given to making sure all drawings are fairly easy to read and understood at first glance. By showing overall views as well as detailed ones the visual aspect of the install becomes reinforced in the mind of the installers.

This documentation should be constantly improved from one project to the next. 

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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