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Island grid increases energy security aspect of microgeneration

Posted by Cathy Debenham on 28 September 2009 at 10:04 am

Security of electricity supply is one of the main reasons that people install their own solar panels or wind turbine. However, a system that is connected to the national grid currently doesn't afford total control.

The benefit of grid connection is that you can sell any excess you generate to the grid, and import electricity if there's not enough sun or wind to make your own. But, your system is automatically shut down whenever there is a power failure on the grid - which is arguably when you need it most - to protect anyone working on the grid.

Until now, that is. The Centre for Alternative Technology (CAT) has just announced a "ground-breaking way of enabling communities to take control of their energy use". Developed at their site in Machynlleth, Wales, where they generate electricity using wind, hydro and solar PV, they have developed an intelligent control system to connect and disconnect to the grid whenever they need to. Called island generation, it is the first system of its kind in the UK.

If grid power fails, the CAT system will be isolated from the national grid, and can continue generating electricity for immediate use, and to charge the battery bank. The back up batteries mean that even if there is no wind, sun, water or biomass there is power for at least three hours.

CAT will use this island system in its training courses and consultancy as a model for Zero Carbon CAT. It will also be a demonstration project for small communities that are interested in an island grid system.


If you have a question about anything in the above blog, please ask it in the comments section below.

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2 comments - read them below or add one


12 VoltzComment left on: 17 February 2010 at 6:54 pm

Whilst Island grid systems are not uncommon, the use of Outback Inverter systems can work in the same way.   Large battery banks can store power for several days as in Off Grid systems, and with the flexibility of the outback system, this can generate up to 30Kw in single phase and 9kw in 3-phase.

The benefit of this kind of system (although expensive initially) is that you can live off the batteries and have the grid as back up when required.   And with wind and solar (and water) energy benefit from the new FiTs.

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Chris Rudge

Chris Rudge from Rudge EnergyComment left on: 14 November 2009 at 11:07 pm

There are a number of different Island Grid units manufatured by SMA (Sunny Boy), that are smaller than the CAT version and can easily be installed to a house or small business. 

Like the CAT version, they give the owner energy security, which is very useful in rural locations. 

Equipment costs start at around £3000 for a Sunny Backup system that can be added to any standard Sunny Boy grid connected PV inverter.

You will need space in a garage or similar to install a battery set as well as the control boxes. Bateries need to installed in a well ventilated place, not inside the house. A garage is ideal!

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