EV Solar Products
2655 N. Highway 89
Chino Valley, AZ 86323
ph:928-636-2201   fax: 928-636-2015
e-mail: info@evsolar.com

Sunny Solar and Family

Prescott, AZ
On the following pages we have put together a complete example of a system sizing. We have completed the power consumption worksheet for a fairly typical household. Following the completed worksheet we have a short analysis of this household's power usage, as well as a price estimate for this system. The worksheet is figured for winter consumption, as that is when the least amount of power is being generated.

Appliances
Watts/Hour
Hours of use/Week
Avg. watt hours/Week
blender
300
x
.5
=
150
CD player
35
x
5
=
175
coffee maker
1000
x
10
=
10,000
computer
125
x
14
=
1750
dryer (gas)
350
x
2
=
700
furnace blower
700
x
21
=
14,700
garage door opener
350
x
1
=
350
hair dryer
1200
x
1
=
1200
iron
1000
x
.5
=
500
microwave
1500
x
1
=
1500
printer: laser
400
x
1
=
400
refrigerator (20cf)
150
x
70
=
10,500
18" satellite dish
30
x
10
=
300
toaster
1200
x
1
=
1200
TV - 25" color
150
x
14
=
2100
vacuum cleaner
1000
x
.5
=
500
VCR
40
x
4
=
160
washing machine
500
x
1
=
500
Lights:  
 
 
42W halogen
42
x
7
=
294
25W comp. flour. (1 bulb 2 hrs/day, 1 bulb 4 hrs/day, 1 bulb 1 hr/day)
28
x
49
=
1372
Total watt hours per week
=
48,351
Total watt hours per day in winter (watt hours per week divided by 7)
=
6907


System Analysis
For this system sizing as is, Sunny Solar will need approximately 14 165-watt modules and 24 L-16 batteries to run a daily load of 6907 watt hours. This requires a fairly large system. At this time it would be good to go back and review the household's power consumption in order to see if there are ways to reduce power usage.
With another look at the example, one can see three appliances that stand out as potential items to consider in the reduction of power consumption: the furnace blower at 14,700 watt hours per week, the coffee maker at 10,000 watt hours per week, and the refrigerator at 10,500 watt hours per week. The coffee maker is easily eliminated by replacing it with an alternative method of making coffee. The furnace blower can be replaced with a wood stove, with a heatering system that doesn't use blowers, or with a more energy efficient heating system. This would be a good time for Sunny Solar to consider whether a passive solar alternative is feasible in an already built residence. When building a new home, however, an energy efficient design can drastically reduce the need for heating and cooling from the start.
The other large power consumer in the house is the refrigerator. In this case it is already a fairly energy efficient model, so in order to lower the amount of electricity used in this household, Sunny Solar could switch to a small (7.8 cubic ft.) propane refrigerator, or small (11.5 cubic ft.) DC refrigerator. However, the trade-off in refrigerator size may not be worth the cost savings.
By eliminating the furnace blower and coffee maker the house load is reduced to 3403 watt hours per day which requires about 8 165-watt modules, and 20 T-105 or 12 L-16 batteries.

Cost Estimates
Cost is an important factor when considering what size system to purchase. In this case, Sunny Solar has several options: to get a system that will run the original house load of 6931 watt hours per day; or to eliminate the coffee maker, the furnace blower, and/or the refrigerator in order to reduce the size of the system. To decide which option is best, she will need to consider the cost of using an alternate source of heat and replacing the refrigerator compared to the cost of the solar modules.
For the 14 module system, the cost would be about $24,400*. By reducing the system to 8 modules, the price drops to around $15,300*. The cost difference between these two systems should outweigh the cost of finding an alternate source of heating. The next consideration is the refrigerator. As mentioned above, replacing the refrigerator can reduce the amount of energy used. However, other factors, such as size and the cost of a new refrigerator, may outweigh the benefits.

*Note: These are approximate prices. They do not include the cost of installation or the mounting structures. Please contact us to receive an accurate quote for your particular system.


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