Solar power production in Australia

 

There is no magic to predicting solar production. Australia gets more solar sunshine than anywhere else on planet Earth. It's highly predictable if measured over months and years rather than over a few days or weeks. It doesn't matter what panels or inverter you have (unless you have shade). The calculator below is currently only configured for Perth. We are adding Brisbane, Melbourne, Sydney and Adelaide soon.

The solar production calculator is currently configured below works within 1-2% accuracy for an unshaded installation any Tier 1 brand of solar panel.

Use our interactive table below to calculate power production (Perth, Australia only).

Enter the total kW of panels for each of your roof orientations
e.g. If you have 10 x 265W panels on North and 10 x 265W panels on West, then enter 2.65 in both the N and W grey section and press tab or enter.

Under the table is a second calculator that works out your electricity bill savings based on the data you enter in the first table.

kW of panels (e.g. 5.5) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual Avg. Per Day % to N

Annual electricity bill savings

Daytime power consumption Savings Year 1 Savings Per Bill


Solar cells degrade in output every year by about 0.6%, you will need to factor this in for an older installation.

What is more important to your hip pocket than just overall production, is when you USE power. If you come home from work/school and switch on lots of things, then an afternoon sun West facing roof might be better for you, financially, than North.

Under the power production figures is a calculator showing what your cost savings would be if your daytime power use was 5,10, 15, 20 or 25 kWh per day.
This is based on electricity prices of 26 cents for units of solar power used and 7 cents for units of surplus power exported back into the grid. We will soon be adding the facility for you to enter your own rates.
Please note that this is your DAY power use, not Total. Solar only works when the sun is shining, so you either use it, as it is made, or it is exported back to the grid.
When batteries become affordable, then the surplus solar can be stored and used at night, greatly improving the financial return. Not yet though.

The next thing we look at is how the sun transits across the sky through the seasons and WHEN during the day solar power is made.

Most people know that the only two days of the year that the sun actually rises due East and sets due West are March 21st and September 21st, but it surprises a great many people how FAR South East the sun rises in Summer, and sets in the South West. In fact in January the sun is due West at about 3.30pm !!

You can also see that the arc is narrow, meaning the sun is more 'overhead' than the Winter picture shown underneath. It barely gets above Northbridge in the picture.

July image below. The Sun is rising in the East North East and setting West North West.

Notice how low in the sky the sun is with the top of the arc at Noon stretching up as far as Landsdale in the North in this picture.

Being so low in the sky greatly reduces solar production.

The tables below show WHEN the solar power is produced, every two hours, from dawn until dusk.

East facing roof

86% of the solar production is achieved, on average across the year by 2pm and over 97% by 4pm
Summer power production is quite evenly spread from dawn to 4pm

Winter power production is very concentrated to between10am and 2pm

 
Dawn to 8am
8am to 10am
10am to Noon
Noon to 2pm
2pm to 4pm
4pm to 6pm
6pm to Sunset
Jan
15%
23%
25%
21%
13%
3%
0%
Feb
12%
23%
25%
21%
14%
4%
1%
Mar
8%
25%
28%
23%
13%
2%
0%
Apr
7%
26%
30%
24%
11%
12%
0%
May
1%
26%
36%
27%
9%
1%
0%
Jun
1%
15%
39%
34%
10%
1%
0%
Jul
0%
15%
33%
35%
14%
3%
0%
Aug
3%
26%
33%
26%
10%
2%
0%
Sep
3%
24%
34%
26%
10%
3%
0%
Oct
7%
21%
33%
23%
13%
3%
0%
Nov
16%
25%
26%
21%
11%
2%
0%
Dec
17%
23%
24%
21%
12%
2%
1%
 
Ave
7.55%
22.75%
30.49%
25.06%
11.64%
2.33%
0.18%
Cum
7.55%
30.3%
60.79%
85.85%
97.49%
99.82%
100%

 

North facing roof

As with the East facing roof, North produces virtually no power after 6pm year round,
and virtually nothing before 8am in Winter

Production is very evenly spread, year round, from 8am to 4pm

75% of daily power, on average, is produced before 2pm, and 95% before 4pm

 
Dawn to 8am
8am to 10am
10am to Noon
Noon to 2pm
2pm to 4pm
4pm to 6pm
6pm to Sunset
Jan
5%
18%
24%
24%
20%
9%
1%
Feb
4%
17%
23%
24%
22%
9%
1%
Mar
3%
17%
25%
27%
20%
8%
0%
Apr
3%
17%
26%
27%
21%
6%
0%
May
1%
15%
29%
30%
22%
3%
0%
Jun
0%
15%
30%
31%
21%
4%
0%
Jul
0%
14%
30%
31%
22%
3%
0%
Aug
1%
17%
30%
31%
18%
3%
0%
Sep
3%
18%
28%
28%
16%
6%
0%
Oct
6%
20%
28%
27%
17%
2%
0%
Nov
7%
21%
27%
26%
16%
2%
0%
Dec
7%
19%
24%
24%
19%
7%
0.%
 
Ave
3.36%
17.23%
27.16%
27.45%
19.51%
5.11%
0.18%
Cum
3.36%
20.59%
47.75%
75.2%
94.71%
99.82%
100%

 

West facing roof

Worried about late afternoon shade from trees hitting your West roof after 6pm ?

Don't be...Only 0.45 % of your production happens after 6pm, whereas 2.88% HAPPENS BEFORE 8AM.

Over 40% of your average production happens before mid day and 90% by 4pm.

 

 
Dawn to 8am
8am to 10am
10am to Noon
Noon to 2pm
2pm to 4pm
4pm to 6pm
6pm to Sunset
Jan
5%
15%
22%
23%
21%
12%
2%
Feb
3%
15%
23%
26%
22%
10%
1%
Mar
2%
14%
23%
26%
22%
12%
1%
Apr
2%
14%
25%
28%
21%
10%
0%
May
1%
14%
27%
30%
22%
7%
0%
Jun
0%
13%
29%
26%
19%
13%
0%
Jul
0%
15%
29%
30%
22%
4%
0%
Aug
1%
4%
28%
30%
20%
8%
0%
Sep
2%
14%
25%
28%
21%
9%
0%
Oct
4%
15%
24%
27%
22%
9%
0%
Nov
5%
17%
24%
25%
20%
9%
0%
Dec
7%
10%
16%
28%
24%
13%
1%
 
Ave
2.88%
14.05%
24.58%
27.09%
21.39%
9.57%
0.45%
Cum
2.88%
16.92%
41.51%
68.59%
89.98%
99.55%
100%

 


solar4ever.com.au is the web site for Good Day Mate Pty Ltd trading as SOLAR4EVER Company registered in WA on 26th October 2008 (A.C.N.133884938)

Contact Detail :


Solar4Ever
Telephone : (08) 6102 2527
Email: info@solar4ever.com.au