Filling out a load chart
Below are a couple of load charts. You should make up your own blank example for your own system. The purpose of a load chart is to determine what you want to run and how much power it will use. Below is a pretty basic method of determining your power requirements.
The first chart below is for a small cabin with some really basic appliances. It assumes 4 sun hours per day and factors the load by 0.7 to allow for inefficiencies.
Appliance |
Wattage |
|
Hours (per day used) |
|
Electrical load |
Reading light |
15 |
x |
2 |
= |
30 |
Living area light |
20 |
x |
4 |
= |
80 |
TV |
120 |
x |
3 |
= |
360 |
Phone charger |
8 |
x |
1 |
= |
8 |
Total Daily power requirement |
478 |
Efficiency factor 0.7 (478 divided by 0.7) |
682.8 |
Total load to give 4 days autonomy: (683 x 4) |
2732 |
Battery voltage: 12 volts, battery capacity determined by maximum discharge of 30%. 2732 = 30%. 100 % determined by (2732 ÷ 30) x 100 |
9106 (watts) |
Battery capacity in amp/hours = 9106 ÷ 12 |
758 (amp/hours) |
Solar array size based on 4 sun hours per day average = factored power requirement (683 watts) ÷ 4 (sun hours per day) |
171 (watts) |
The following chart is for a house with a typical requirement given a set budget. With a household solar design it is far better to use the more comprehensive design criteria of Australian Standard (AS) 4509.2 - 2002 but this chart displays the basics for a house with basic (as far as Aussie homes) appliances and typical needs
Appliance |
Wattage |
x |
Hours per day
(Note 1) |
= |
Electrical Load |
Lighting |
Living room |
20 |
x |
4 |
= |
80 |
Dining room |
20 |
x |
4 |
= |
80 |
Bedroom 1 |
15 |
x |
1 |
= |
15 |
Bedroom 2 |
15 |
x |
1 |
= |
15 |
Bedroom 3 |
15 |
x |
1 |
= |
15 |
Bathroom |
15 |
x |
2 |
= |
30 |
Study |
15 |
x |
2 |
= |
30 |
Outside |
50 |
x |
0.5 |
= |
25 |
Others (laundry, toilets, shed etc) |
60 |
x |
1 |
= |
60 |
Total lighting load |
350 |
Kitchen |
Refrigerator |
140 |
x |
6 (note 2) |
= |
840 |
Blender |
500 |
x |
0.2 |
= |
100 |
Microwave |
1500 |
x |
0.5 |
= |
750 |
Juicer |
600 |
x |
0.1 |
= |
60 |
Total kitchen load |
1750 |
Lounge Room |
TV |
140 |
x |
4 |
= |
560 |
DVD |
25 |
x |
2 |
= |
50 |
Stereo |
25 |
x |
1 |
= |
25 |
Computer |
140 |
x |
2 |
= |
280 |
Total lounge room load |
915 |
Bedroom Appliances |
Electric blanket x 1 |
120 |
x |
0.5 |
= |
60 |
Kids TV |
80 |
x |
1 |
= |
80 |
Kids TV 2 |
80 |
x |
1 |
= |
80 |
Rechargeable devices |
40 |
x |
1 (Note 3) |
= |
10 |
Bedside clock |
5 |
x |
24 (Note 4) |
= |
120 |
Total bedroom load |
380 |
Laundry |
Washing Machine |
250 |
x |
1 |
= |
250 |
Iron |
900 |
x |
0.2 |
= |
180 |
Total laundry load |
430 |
Workshop |
Power tools |
1500 |
x |
0.1 (Note 5) |
= |
150 |
Other |
Phones, toys, vacuum, tools etc. |
1000 |
x |
1 |
= |
1000 |
Total household load (note 6) |
4975 |
Factored daily load (4945 ÷ 0.7) (Note 6) |
7094 |
If you are contemplating a solar design of these proportions or larger you really should plan using AS 4509.2 - 2002. In the book "Renewable Energy" "Design, installation and use for home owners" planning using AS 4509 is explained in detail as the standard is quite comprehensive and was written by some pretty clued up people!
Click here for more info on this book
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