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Grid Tie Solar Kit Systems, How to size yours

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Grid Tie Solar Energy Systems, For an existing home, Sizing information,

Size your grid tie kit system:

1 Gather up your last 12 months electrical energy bills.
2 Total the kWh from all 12 electric bills and divide it by
365 days. (kWh equals 1000 watts)
3 Look on a Solar isolation map and find the average Peak
Sun hours for your area.
4 Divide lines two and three.
5 To allow for heat losses in the solar modules, voltage
loss in long wire runs, power loss in the inverter (inverters
use energy to operate) add 15%.
6 Get a site shading survey, This will track the sun’s path
and give the effect a tree, fence or house might have. Add
this percentage to the above.
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Additional Options
Fronius IG Plus 11.4 Inverter
$6,202.51
SMA SB 8000US Grid Tie Inverter with DC disconnect
$3,547.55
Grid Tie Systems
Example:

12 months electric bill shows a total of 6,600 kWh. Add three zeros to the end to get total watts
(6,600,000 watts).

6,600,000 / 365 = 18,082 watts per day

For Northwest Arkansas the average Peak Sun Hours are from 4 to 5 hours. 18,082 / 5 =
3,616 watts in solar modules.

Now lets add back in the heat loss, inverter and wiring loss of 15%.

3,616 * 1.15 = 4,158 watts in modules

To completely wipe out your energy bill you will require 4,158 watts in solar modules as long as
there is no problem with the shading survey.

Look for a solar energy grid tie system in this list by looking at the array size. All you need next
is to find a contractor in your area to install it. Or you can do it your self and hire an Electrician
to get the permit and twist the wires.

You will want an inverter that will be able to back feed the grid all of the solar electric power
produced. No need for any larger because that would be over kill and waste your money. If by
chance you have a well pump etc. And it requires more power than your power inverter can
produce. The system will switch over to the grid to get the extra energy.

The Inverter sizing is a little tougher to do. Every brand and size of grid tie solar energy
inverters have a voltage min and max. Solar modules when hot in the summer produce lower
power and in the winter time with bright sun will over produce. This has to be taken in to
account or in the summer the solar electric voltage could be too low to start the grid interactive
inverter. While in the winter the voltage could get too high and burn out an inverter.

At this point you need to pick a pre designed kit or give the above information to a solar
electric dealer to allow him/her to design one for you or review your kit system choice.