Shading Analysis

People can under estimate how much power can be lost through shading on their solar panels. What good is having a solar power system in Perth’s long summer days if the panels are shaded.

In reality most systems will catch some shade at different stages of the year, but the question is how much will I lose?

Below we explore 3 significant points of the suns annual path, the southern summer solstice (December), the equinoxes (March and September) and the winter solstice (June). For simplicity let’s assume that a December day has 14 hours of sunlight, March and September days have 12 hours and a June day has 10 hours. Each hour of the day is allocated a percentage for losses should your solar panels become shaded.

 

Month of December

AM

5-6

6-7

7-8

8-9

9-10

10-11

11-12

PM

6-7

5-6

4-5

3-4

2-3

1-2

12-1

1%

2%

4%

7%

10%

12%

14%

 

Month of March/September

AM

6-7

7-8

8-9

9-10

10-11

11-12

PM

5-6

4-5

3-4

2-3

1-2

12-1

1%

4%

7%

10%

12%

14%

 

Month of June

AM

7-8

8-9

9-10

10-11

11-12

PM

4-5

3-4

2-3

1-2

12-1

2%

7%

11%

14%

16%

To avoid these losses, regular trimming and pruning of trees is essential. Also ensure when choosing your initial location that no neighbouring trees will become an issue in the future.