Inter-row Shading on the Tropic of Cancer

From HeatSpring.com PV Boot Camp Discussion Board

Q:

Wonderful presentatation. The height and distance in PV panel is discussed as 1:3, if i reduce this distance, How much energy loss will be there if there is no shading? If we install PV panel in roof top means there is less area, so, it is not possible to give long distance between the PVs. So, what is your advice?

A:

The height to distance shading ratio can be variable based on latitude, space available, the type of PV system and expectations.

For your location on the Tropic of Cancer 23.44 latitude, I would say that a 2:1 distance to height shading ratio is plenty good to the south east and west and no shading worries to the north.

Most designers with repeating rows tilt the modules at about 10 degrees tilt, even at higher latitudes, so that they will not have as much inter-row shading and they can fit more. A 10 degree tilt will not be optimal, but very close to optimal for production.

There is also a way to do trigonometry for inter-row shading calculations, which can be overwhelming for most people, especially an entry level course.

I have an example of an inter-row shading calculation here in my notes for an old class:

http://www.pvstudent.com/Advanced-PV-Course-Notes-2.html

Also, I have an inter-row spacing calculator, where you will have to enter i formation for your latitude and module width.

http://www.pvstudent.com/Inter-row-spacing-calculators.html

These calculations give you no shade at 9am on winter solstice.

Often when you buy rooftop ballasted PV systems, the inter-row space is included with the product.

Thanks,

Sean White

From HeatSpring.com PV Boot Camp Discussion Board