How Does A Home Solar System Connect To My Power Company?

Although a home solar power system can exist independent of the power utility's grid, that is not normally the case in a typical residential setting.

Grid-tied Solar Power

Grid-tied solar systems are connected to the local power utility. At night and during off-peak hours, power is purchased from the utility. This process is transparent to the homeowner.

Power production and use is monitored via a system called net metering. A smart meter is installed in the home that is capable of running both forwards and backwards. At the end of the month, the homeowner pays the difference, or in some cases is paid by the power company.

This arrangement is put in place via an interconnection agreement with the power company. Some utilities require the installation of a second meter and simply do the comparison of production versus consumption manually for billing purposes.

Smaller utilities that have never negotiated interconnection agreements can be frankly difficult about the process, but by law they are required to allow your system to tie into their grid.

(This is an instance where working with a professional solar installation firm can be a distinct advantage as they will arrange the interconnection agreement as part of their overall services.)

In terms of equipment, an on-grid system will consist of a photovoltaic array wired to a DC disconnect. Power is fed through an inverter to the AC breaker panel and from there to the home. The smart meter reads both power used and power generated.

A Special Note About Grid-Tied Systems

Unless a grid-tied system also has a back-up battery and can be removed from the grid via a switch-over component, you will not have electricity during a power outage. On a grid-tied system the inverter must be rigged to shut down in the event of power loss to prevent electricity from feeding back into the grid and potentially harming utility workers.

Off-Grid Solar Power

Off-grid systems work with complete independence from the power company's grid. All electricity generated by the solar array is fed directly into the home or into deep storage batteries for use at night and in off-peak periods.

Most homeowners with off-grid systems also maintain a secondary energy system, either a generator, or another alternative energy source capable of feeding power into the home's batteries. If the site is suitable, a residential wind turbine can easily be paired with an off-grid solar array.

The off-grid equipment is identical to that used in a grid-tied system, but with a back-up generator or secondary power source wired into the inverter, which then connects to the AC breaker with no additional connection to the utility grid present.

Both types of home solar systems have no moving parts and are largely maintenance free, a fact that brings down one element of the long-term cost of maintaining and installing a residential solar energy system.

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One Response to “How Does A Home Solar System Connect To My Power Company?”

  1. Where To Buy Solar Panels - Solar Panel Installation - Solar Power Companies Says:

    […] will also want to know when the interconnection agreement with the local power company will be concluded and when your system will actually start to interact with the grid. There should […]

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