For an On-Grid system it is down to budget and space
available.
Off-grid, firstly you need to calculate the amount of power you will
require. This is done by finding the watt rating of all the devices you intend
to run. Then times this value of each device by the time you intend on running
it for. This will give you a total watts draw value. .
eg. You have a shed light that you wish to run on solar. The bulb
uses 11w. You wish to use it for 20 hours a week.
11 x 20 = 220w
To make this value into the amount of power you will draw from the
battery you divide by 12 (since the battery is 12v)
220 / 12 = 18.33 round up = 19
You then need to take into account when you plan to use it. If it is
all year round then you need to make the calculation based on the winter value
of 0.05ah /w/day. If only during the summer then 0.7ah/w/day. Times the
necessary value by 7 to account for the full 7 days of the week.
For only summer use:
0.7 x 7 = 4.9 ah / w / week
Then take the AH figure you require for the weeks power. ie 19ah and
divide this by the generation value. ie 4.9
19 / 4.9 = 3.87watts PV required
Winter use:
0.05 x 7 = 0.35 ah / w / week
19 / 0.35 = 54.3 watts PV required
As you can see there is a fair difference between winter and summer
values in the IN. Please be sure to take this into account when calculating.
Please contact us by email info@finegreensolar.com or on 0888 333 5220 if you are
unsure or wish to discuss your project further.
