Practical Solar Power
Solar Power-How it works physically
The sun's light strikes a solar panel.
- The solar panel uses the light-energy to make a direct current, DC,
That DC electricity is useless because you cannot plug any house hold
device into it and get it to work (except possibly your toaster or
curling iron and they would
not work reliably). Everything in your house has been designed to
work with alternating current, AC, electricity.
- The DC electricity flows into an inverter, which converts the
DC electricity into AC electricity.
- The AC power is attached to your home electrical system at the
Solar Power-How it works regulatorally
Grid tied vs. Non-Grid tied
With the solar power system hooked into your house through your
circuit breaker panel you have a grid tied system, it is tied the
power grid that you already rely on
(in western Pennsylvania [excluding greater Pittsburg] that is Penn
's electrical grid who is a subsidiary of
Having a grid tied system means that
You can still rely on the grid when you don't make enough electricity
for your house (you are an energy importer).
When you make more electricity than you can use it feeds back onto the
grid and makes your meter spin backwards (you are an energy exporter).
You help keep the dirtiest electricity power plants off line. You
make energy when it is sunny, a peak time for running air conditioners.
You have to apply to connect your energy generation equipment to the
Having a non-grid tied system means that
You must have batteries to store energy for the times the sun is not
bright enough for your needs.
You can't rely on the grid when you don't make enough electricity
for your house, the lights go out and your fridge stops.
You need a system big enough to cover all of your energy needs from
There is no application and you have bragging rights for being off the grid.
In my opinion the only benefit of having a non-grid-tied system is the
bragging rights and skipping the interconnection application.
Applying to tie your system to the grid.
Connecting to the power grid with small scale power generation
equipment (<50kW for residences) is called interconnection.
Pennsylvania amended the laws governing small energy generators in
2008 and mandated net metering with the power company responsible for
installing the meter capable of turning backwards at no charge to
You must apply
to make the connection before you install your system. To fill out
the application you need
- to know your energy use history (just get out
your old electricity bills) since the net metering law is based on the
idea that you will not be a net exporter of energy year after year (but you
can be for months at a time).
to estimate the amount of energy you will produce.
provide some specifications about the inverter you will be using.
provide a one-line diagram. This shows in a cartoonish way how the
electrical energy moves from the solar panels through the inverter
into your breaker box and out to the utilities meter. It is important
to include all of the information that is shown in
First Energy's example (e.g. manufacturer of the breaker box and
amperage of service).
provide a site plan. This tells the linemen how and where to shut off
your solar power equipment if they need to work on the lines so they
don't run into any surprises. First
Energy's example. I drew ours one-line drawing and site plan using the free software called
xfig. It is native to the free software system ubuntu linux and can also be
installed directly on windows using these
to supply the $100 application fee.
We have currently have a complete application in and are awaiting
When the company gives the ok it is provisional, it allows you to
install and test your solar power system. When it is correct, you
must have it inspected by the local electrical inspector.
Solar Power-How it works economically
Pennsylvania and the Federal government have incentives available for
those who install alternative energy systems.
Pennsylvania: The program for solar power money is called
and a good discussion of this program is
available at solar
. Since this is a tax rebate program we couldn't use
it as Westminster College is a tax-exempt entity. The other catch
that I see is that the application must go through a certified
installer, so this may not work for a DIY installation.
Feds: The federal government has a 30/% Solar Investment Tax Credit
which is discussed here
According to the Department of Energy your solar power system
needs to be installed before
December 31, 2016
Where we bought our equipment
, they had
the most straight forward pricing information and were quite
responsive to any needs we had.