Figure 5.1 shows a grid-connected PV installation.
The actual design will require the services of electrical engineers. Note that the inclusion and arrangement of components will also vary with the system and the manufacturers.
Figure 5.1 - A grid-connected PV installation
Starting with the grid, it is essential to contact the electricity supplier and / or national grid company early on and obtain its permission to connect, whether or not any electricity will be exported to the grid. Clients with grid-connected PV buildings will need to ensure that the installation will cause no safety hazards and will comply with technical regulations and recommendations, and that the quality of the power will be acceptable for export to the grid. For example, the grid’s electricity suppliers are likely to require that, in the event of a loss of mains power, the PV installation will close down automatically. This is to give the grid maintenance engineers a non-live system on which to carry out repairs.
It is also important to check early on whether your electricity supply company will pay for any
electricity exported as this has an impact on the economics of the system (as mentioned in Chapter 4). From 2009, electricity suppliers in Ireland will be making export tariffs available to micro-generators representing a significant step forward for the micro-generating technologies.
Whether there will be any significant additional charges for operating a grid connected micro- generator should also be checked.
Metering grid-connected systems is an area currently in flux. Smart meters are now generally available but the cost responsibilities should be clarified with the electricity supply company. Leaving aside the more technical considerations, the basic options are:
One-way metering: Metering on the incoming supply and no metering on the PV output. •
Smart meter – records imports and exports as well as time of day of the import or export. •
The metering strategy to adopt will follow from discussions with the supplier and be influenced by end user requirements. A smart meter would be recommended as it will be cheaper to install during the initial build rather than retrofitting one in the future.
Getting set up for a grid connection in Ireland is straightforward.
Your chosen supplier could take care of the documentation necessary. It is a straightforward form so should be done at no extra cost. They should also take care of the hiring of a RECI or ECSSA certified electrician to carry out the connection to ETCI standards as part of their service.
Form NC6, available from the ESB Networks website, should be submitted well in advance of any grid tie-in.
NC6 is a straight forward one page form which includes: Name, address and co-ordinates of the site •
Contact details •
MPRN number •
Unique number assigned to each meter point o
Printed on the top of your bill o
Installer contact details •
Make, model and serial number of inverter (grid connected electronics) •
Declaration of conformance with “
• Conditions governing the connection and operation of microgeneration” including EN 50438.
Details of generating unit •
Make and model o
Type of technology (wind, PV, micro-hydro, micro-CHP etc.) o
Unit Rating and phases generated o
Details of inverter unit. •
Type-test certification for the inverter (the unit tying the system into the grid) should accompany the NC6 form. The certification required should declare conformance with EN50438 which is the appropriate standard for grid connected units. The suppliers should provide you with this paper work if you are submitting the NC6 form yourself.
You will need an import/export meter to avail of any payment for exported energy. The import/ export meter currently available in Ireland is referred to as an ‘interval meter’. It is now supplied automatically and for free to customers when they submit the NC6 form.
Feed-In-Tariff
ESB Customer Supply and ESB Networks both intend to offer payment for export to domestic customers from 2009. An import/export meter must be installed to avail of payment.
Details of the proposal from ESB Customer Supply can be viewed on their website. An application
form must be filled out and sent to ESB Customer Supply. Before applying for the export
payment you must have concluded the ‘inform and consent’ process with ESB Networks.
9c/kWh
• available from ESB Customer Supply
Scheme is only open to ESB Customer Supply domestic customers •
Scheme has upper limit of 11kW generating unit (as per rating (kWp) of installation) •
Installation of interval meter (import/export meter) required (free to first 4,000 applicants) •
Payment for export will be settled once every 12 months •
Expansion of the scheme to commercial or agricultural customers being considered. •
Customers of other electricity suppliers should contact their suppliers to request a similar facility. The Comission for Energy Regulation (CER : www.cer.ie) has a list of active electricity suppliers on its website. Airtricity and Bord Gáis Energy are the other suppliers to the Irish domestic market at present.
Further to the 9c/kWh offering from ESB Customer Supply a further 10c/kWh payment from ESB
will be available to a portion of the output from the first 4,000 microgenerators connecting in the next 3 years. The payment will be available to all microgenerators and not just ESB Customer Supply customers. The 10c/kWh payment will apply to the first 3,000 kWh exported each year for the next 5
years. This will bring the total export payment available to domestic customers to 19c/kWh for the
first 3,000 units exported, reducing to 9c/kWh thereafter.