TYPICAL WATTAGE REQUIREMENTS OF COMMON APPLIANCES

Cash register: 220 volt 10 - 30 W

Ceiling Fan: 220volt 50 - 80 W

Computers and printers: 220 volt
Modern Desktop PC 50 - 60 W
Colour monitor 70 - 100 W
Black and white monitor 20 - 30 W
Ink jet printer 30 -40 W
Dot matrix printer 80 - 200 W
Laser printer 600 -1200 W
Laptop 10 - 30 W

Fax machines: 220 volt
(Transmit) 20 -30 W
(Receive/print) 40 - 80 W

Hair drier: 220 volt 800 - 1500 W

Hi-fi: 220 volt 40 -60 W

Hi-fi: 12 volt 10 - 20 W

Iron (electric): 220 volt 1200 W

Lights: 12 volt
Fluorescent - 40W equivalent 8 W
Fluorescent - 60W equivalent 15 W
Fluorescent - 75W equivalent 20 W
Fluorescent - 120W equivalent 36 W

Microwave oven: 220 volt
Small 800 W
Large 1500 W

Refrigeration: 220 volt
Ordinary household fridge 400 W x 8 hours a day
Ordinary household freezer 400 W x 8 hours a day
Holdover plate fridge 660 W x 4 hours a day
Holdover plate freezer 660 W x 4 hours a day

Refrigeration: 12 volt Household
Minus 40 225 litre fridge 1000 W a day
Minus 40 150 litre freezer 950 W a day
Minus 40 115 litre freezer 800 W a day
Minus 40 80 litre freezer 600 W a day
Minus 40 60 litre freezer 550 W a day

Refrigeration: 12 volt Clinic
Minus 40 B90/10 litre fridge 720 W a day

Sewing machines: 220 volt
Domestic sewing machine 80 W

Television: 220 volt
Colour 51 to 68 cm 55 - 70 W on newer models
and up to 120 W on old model TV’s

Television: 12 volt
Colour 51 cm 60 W
Black and white 37 and 51 cm 20 - 30 W
Black and white 31 cm 10 - 20 W

Two-way radio
(Transmit) 25 W
(Receive) 5 W

Vacuum cleaners: 220 volt
Domestic type 800 - 1200 W

Video machine (VCR): 220 volt
(When in operation) 16 - 30 W

Washing machine: 220 volt
Cold cycle (wash & spin dry) 500 - 800W
Hot cycle 2000 - 3000W

Hints on saving electricity

RULE 1. IT IS NOT WISE TO USE APPLIANCES WITH HEATING ELEMENTS

RULE 2. CHECK ON THE POSSIBILITY OF AN ALTERNATIVE TO APPLIANCES THAT REQUIRE CONTINUOUS 24 HOUR OPERATION.

 

Solar System Design Form

 

Solar panel sizing:
Total watt-hours/day = .........
System voltage ÷ .........
Total dc amp-hours/day =..........
Battery & wiring losses, safety factor x .2 + .........
Total daily amp-hour requirement = .........
Estimated design insulation ÷ 6
Total solar array current in amps =..........
Solar panel selected --...... watt
Solar panel rated power amps ÷ .........
Number of panels required in parallel = .........
System voltage = .......
Module nominal voltage ÷ .......
Number of panels required in series = .......
Total number of solar panels required = .......

Regulator sizing:
Total solar array current in amps = .......
Regulator selected -- amp over voltage ÷ .......
Number of Regulators required = .......

Battery bank sizing:
Total daily amp-hour required ..........
Reserve time in days x 4
Percentage of use able battery capacity ÷ 80%
Minimum battery capacity in amp-hours = ........
Battery selected -- .... Ah
Battery amp-hour capacity ÷ .......
Number of batteries in parallel = ........
System voltage .......
Selected battery’s voltage ÷ ........
Number of batteries in series = .......
Total number of batteries required .......

 

VOLTAGE DROP ON 12 VOLT WIRING SYSTEM

Permitted Voltage Drop 0.5 Volt (4.17%)

How to use this table:

1. Determine the distance over which you need to supply the power.
2. Determine the current (amps) draw of the equipment to be used on this line.
3. Find the corresponding distance in meters in the left-hand column of the table.
4. Look in the following "Maximum amps drawn" column for the first value, equal to or larger than your calculated current draw.
5. Go to the top of this column to read the appropriate wire diameter size.

Other dc voltage wire size determination:

• With higher input voltages the thickness of wire used is reduced.
• Use the 12volt table figures and divide the wire gauge by two for 24volt or by three for 36volt systems.

 

Distance	Wire Size
in Meter	1.5mm	2.5mm	4mm	6mm	10mm	16mm
	Maximum amps drawn
3	12.5	22.9	36.8	55.1	93.1	147.4
4	9.4	17.1	27.6	41.3	69.8	110.6
5	7.5	13.7	22.1	33.1	55.8	88.5
6	6.2	11.4	18.4	27.5	46.5	73.7
7	5.3	9.8	15.8	23.6	39.9	63.2
8	4.7	8.6	13.8	20.7	34.9	55.3
9	4.1	7.6	12.2	18.4	31.0	49.1
10	3.7	6.8	11.0	16.5	27.9	44.2
11	3.4	6.2	10.0	15.0	25.3	40.2
12	3.1	5.7	9.2	13.8	23.2	36.8
13	2.8	5.2	8.5	12.7	21.4	34.0
14	2.6	4.9	7.9	11.8	19.9	31.6
15	2.5	4.5	7.3	11.0	18.6	29.5
16	2.3	4.3	6.9	10.3	17.4	27.6
17	2.2	4.0	6.5	9.7	16.4	26.0
18	2.0	3.8	6.1	9.2	15.5	24.5
19	1.9	3.6	5.8	8.7	14.7	23.2
20	1.8	3.4	5.5	8.2	13.9	22.1
22	1.7	3.1	5.0	7.5	12.7	20.1
24	1.5	2.8	4.6	6.9	11.6	18.4
26	1.4	2.6	4.2	6.3	10.7	17.0
28	1.3	2.4	3.9	5.9	9.9	15.8
30	1.2	2.2	3.6	5.5	9.3	14.7

 

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