Generation Solar Renewable Energy Systems

Before you begin

Correctly sizing a complete PV system can be a stern challenge. However, you can get a rough idea of your energy needs - and, therefore, of the size and cost of a PV system - by following the two steps listed below.

If it proves impractical to be completely independent with PV, you may consider a grid-connected or a hybrid - coupling PV with another energy source such as diesel, propane, or wind power - system. Also, you may consider starting off with a small system which can be expanded at a later date.

Step 1

How much energy will you be using?

There are two ways to go about this:

• Method 1

Your local utility sells energy per kilowatt hour (kWh).

Note: A kWh is simply a multiplication of power (kW) by time (h).

If you want to replace all or part of your utility supply then simply use last year’s bills to estimate your energy needs. Calculate your average daily kWh usage, and convert this figure into watt hours (Wh).

Example: Using utility bills to estimate energy needs

Last year’s total utility bills	= 2,555 kWh/year
Daily average (divide by 365)	= 7 kWh/day
Convert to Wh (multiply by 1,000)	= 7,000 Wh/day

• Method 2

If utility bills won’t provide the information you need, you will have to make a list of the electrical loads which you want to power with your PV system. For each item, estimate the number of hours it will be used per week, and multiply this by the item’s rated wattage. Total up AC and DC items separately.

Example: Listing weekly energy loads

Energy load	W	x h/wk	= Wh/wk
Fluor. lights	9	63	567
Ceiling fan	30	56	1,680
Colour TV	80	7	560
DC total			2,807
Laptop	35	10	350
CD player	35	12	420
AC total			770

If you don’t know the rated wattage of any particular item, check the list of typical figures below. Most electrical appliances state their rated wattage on either their base or back, or they may display EnerGuide labels, which list the kWh consumption per month. Convert this figure to Wh per week and add it to your totals.

Typical rated wattage for common items

Item	Typical Wattage
Coffee Pot	140-200
Coffee Maker	800-900
Toaster	800-1,500
Blender	300
Microwave	600-1,500
Dishwasher, excluding hw	1,300
Washing Machine, Auto	500
Washing Machine, Manual	300
Vacuum Cleaner	200-800
Sewing Machine	100
Iron	1,000
Clothes Dryer, Electric	400
Clothes Dryer, Gas	300
Water Pump	250-500
Ceiling Fan	10-50
Table Fan	10-25
Electric Blanket	200
Hair Dryer	1,000
Shaver	15
Computer, Laptop	20-50
Computer, PC	80-150
Printer	100
Typewriter	80-200
VCR	40-120
Television, Colour	70-400
Television, B&W	20-250
CD Player	35
Stereo	10-30
Electric Clock	2-5
Satellite Dish	30
CB Radio	4-6
Radio Telephone, Idle	12
Radio Telephone, Transmit	96
Fridge / Freezer, 20cf*	400-500
Fridge / Freezer, 16cf*	300-400
Fridge, Sunfrost, 16cf DC*	112
Fridge, Sunfrost, 12cf DC*	70
Freezer, 14 cf ff*	250-350
Freezer, 14 cf*	150-250
Freezer, Sunfrost, 19 cf*	112

* Regular fridges and freezers are on 15 hrs/day; Sunfrost fridges: 7 hrs/ day; Sunfrost freezer: 10 hrs/day.

Step 2

How many PV panels will you need?

Now make two calculations:

• Calculation 1

Batteries, charge controllers, inverters, and cable all introduce losses to your PV system.

Allow for this by multiplying your total AC loads by 1.25, and your total DC loads by 1.20 (they bypass any inverter). Then add together your adjusted loads, to find your daily Wh requirements.

Note: If you have been working in Wh/wk, divide your total by seven to find your daily Wh requirements.

• Calculation 2

Divide your daily Wh requirements by the number of hours in a day during which you expect the panels to be exposed to full sunlight. This calculation determines your peak watt requirements (Wp). You can use the table below to estimate peak sunlight hours if you live in Canada.

Average peak sunlight hours in Canadian cities

Province, City	Summer	Winter	Yearly
AB, Edmonton	4.95	2.13	3.75
AB, Suffield	5.19	2.75	4.10
BC, Kamloops	4.48	1.46	3.29
BC, Vancouver	4.23	1.33	3.14
MB, Winnepeg	5.23	2.77	4.02
NB, Fredericton	4.23	2.54	3.56
NF, Goose Bay	4.65	2.02	3.33
NF, St. John’s	3.89	1.83	3.15
NWT, Fort Smith	5.16	0.88	3.29
NS, Halifax	4.02	2.16	3.38
ON, Ottawa	4.63	2.35	3.70
ON, Toronto	3.98	2.13	3.44
PEI, Charlottetown	4.31	2.29	3.56
PQ, Montreal	4.21	2.29	3.50
SK, Swift Current	5.25	2.77	4.23
YK, Whitehorse	4.81	0.69	3.10

You can now select PV panels to meet your daily Wp requirements. As an example, if you need 235Wp, you might choose five 50W or four 60W panels.

Got lost somewhere between "electrical loads" and "peak watt requirements"? Don’t stress - contact Generation Solar for helpful and friendly advice.

Now what?

If PV power is a feasible option for you, then you may want to check out our Store & services section.

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