Grid Tie Solar Power
Grid tie solar power is a popular way to use solar electric panels. With grid tie, solar panels are connected to a mains inverter and surplus electricity generation is sold to the national grid, rather than being stored in batteries.
The idea is simple - if a grid-tied home is generating more electricity than it uses during the day, this is made sold to the national grid on a feed in tariff and is available for other people to use. In the evening, when the grid-tied home is consuming more electricity than it is generating, it then takes electricity from the national grid.
Grid tie is being sold as a way to reduce your carbon footprint and make a positive contribution to the environment.
Solar Regulations G83/1
Here in the UK, connection to the national grid is completed under the regulations covered in G83/1. All grid tie systems need to use certified equipment and be installed by a certified installer. A full list of certified installers can be found on the Micro Generation Certification website.
The maximum sytem which can be installed under G83/1 is 16 Amp, this is equalivant to around 3.6 kW, on a single-phase supply and 11 kW on a three-phase supply.
Once your grid tie solar power system is installed your installer will provide the distribution network operator (Electricity supplier), with the installation commissioning confirmation, this needs to be done within 28 days. You will then need to contact your electricity supplier to arrange the feed in tariff.
Feed in Tariff
In the UK (excluding Northern Ireland) feed in tariffs were started on 1st April 2010. For solar PV all installations completed between 15th July 2009 and 31st march 2010, the tariff is 41.3p per k/w for 25 years. The tariff levels are due to be reviewed in 2013, although the current government may review it earlier.
Grid tie solar power disadvantages
Unfortunately, in the UK at least, the real benefits of grid-tie systems are questionable and there is a very real concern that these systems do nothing to reduce carbon emissions in the real world: during the day, the national grid has a surplus supply of electricity and power stations are still generating huge quantities of carbon emissions whilst standing idle. During the evening when everyone is demanding electricity, all the power stations are running at full capacity and additional power is provided by running diesel and gas powered generators.
As grid-tied solar power does nothing to increase power availability during peak demand times, and households with a grid-tie solar system are consuming electricity themselves during peak demand periods, there is no environmental benefit for grid-tie in its own right.
This is likely to change in the future as new designs of power stations become available and the national grid start storing electricity during off-peak times, but neither of these are short term goals and in the meantime, for most applications, grid tied solar electricity has no positive benefits to the environment
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