WHAT IS ON GRID SOLAR POWER SYSTEM?





















  • An on grid(or grid tied)system is connected to your local electrical grid. This system works by
  • using a two-way electrical meter. When your house or building needs more energy than what 
  • the solar panels are generating the system pulls extra electricity from the grid. Whenyour system
  • is generating more energy than your house or building needs, the system sends the excess electricity
  • to the grid. On grid system sometimes include battery storage as well, but mostsystem  owners  prefer
  • not to use a battery as it increases the complexity. 
  • This system, once installed and connected to your local electric utility provider, can generate 
  • electricity for your home and business under the following scenario:
  • 1. When you use more electricity than the grid tie system, the power grid provides the difference.
  • 2. However, when your grid tie solar system generates more electric power than what you are
  •  using, the excess electricity will redirected to the grid for others to use — earning you credits
  •  toward your grid usage based on an existing renewable energy policy of your local electric utility 
  • provider.
  • Depending on the size of the grid tie solar system that is installed in your location, this system will
  •  result to any of these opportunities:
  • • A reduced monthly electric bill
  • • No monthly electric bill
  • • A credit on your monthly bill (if the local electric provider has a net-metering program, this 
  • could be an actual check on the amount of excess solar electricity produced and sent to the grid)

  •  (A) Strings of Photovoltaic Panels
  • This are the photovoltaic modules that will be on your roof. They are wired in series "strings" 
  • for maximum efficiency and minimal labor costs. Each solar installation may have one or multiple 
  • strings depending on the circumstances. Each of these strings connect in parallel at the combiner
  •  box, which is explained below.


  • (B) DC Combiner Box

  • The combiner box serves as a location to electrically "combine" the multiple strings of solar 
  • panels. The box is typically located close to the panels to eliminate the need to have multiple long 
  • wire runs back to the inverter. At the output of the combiner box, there is one set of direct current
  •  (DC) wires running to the inverter.


  • (C) AC Inverter

  • The Alternating Current (AC) Inverter is used to convert the DC power created by the
  •  photovoltaic panels to the 110V/120V/220V/380AC depending on different households. In reality, 
  • the output of your solar inverter is typically setup for a 240VAC split-phase operation, since this is 
  • what is actually coming down from the utility line transformer. For a more in-depth explanation of
  •  "split-phase" and why we use AC in our house instead of DC, see our electricity 101 page. This
  •  240VAC output connects directly to your existing utility panel which is explained further below.


  • (D) Existing Utility Panel

  • Your existing utility panel contains your electrical usage meter, your electrical breakers, and
  •  power line connection coming into your house from the utility pole. You are effectively making
  •  a direct connection (through a breaker and your power meter) between your inverter and the utility grid.


  • (E) Your Existing Loads

  • There is no re-wiring required to your existing electrical system in your house! Your existing
  •  loads can't "see" the solar system. Your solar system works interactively with the grid, and is 
  • effectively supplementing the power you receive from the utility. When the sun is up and your 
  • system is producing more power than you are using, you are essentially using 100% clean solar power!

  • (F) The Grid and the Payoff

  • Since your inverter is directly connected to the power line coming from the utility, along with 
  • NET Metering Agreement from the local utility company (which the solar contractor will
  •  facilitate), you are enabled to back feed power into the grid when your photovoltaic system is 
  • producing more power than you are using in your house or business. This is where the investment 
  • of a solar power system shines. As you are back feeding power into the grid, you earn credits with 
  • the utility company, which are then used to offset the amount of power you use from the grid.


  • (G) Earth Ground

  • Electrical codes require your entire system to be connected to an earth ground. The earth ground
  •  provides life safety and fire protection from both electrical faults and lightning strikes. 
  •  Take note, that alone, grid-tie systems do not provide back-up power in the event of a grid
  •  failure. Solar inverters have a feature known as "anti-islanding," which cause them to switch off
  •  during a power failure so that they do not energize the grid when the lineman is working on it. 
  • This can be overcome by utilization of a hybrid solar system, which incorporates an independent
  •  backup source, such as batteries or a generator.