Just under 40% of current UK greenhouse gas emissions can be attributed to the energy supply sector with high losses mainly due to wastage from centralised production and consequent long distance transmission. Electricity produced locally and by renewable sources, encouraged by generous sell back tariffs, is thus making micro-generation a rapidly growing business opportunity for a new set of MCS qualified installers. It has even been estimated that micro-generation could meet 30-40% of UK electricity demand by 2050.
Domestic micro-generation is still very much an emerging market, currently struggling from varying advice with a number of regulation and official documents giving contradictory guidance. There has also, until now, been little dedicated product available from trusted and established electrical manufacturers to simplify and hence speed up installation, and often make the finished system safer for the end user.
Currently therefore a typical installation can consist of a collection of disparate circuit protection items, painstakingly assembled by the contractor, for each application, and consequently needing to be individually wired. Anomalies, such as where circuit protection devices should be located, and how they are provided vary according to a contractor’s own interpretation of the regulations, current guidelines and the design of micro generator inverters installed.
Wylex has been commended in the past for having provided much needed clarification, guidance and off-the-shelf product availability when the 17th edition of the wiring regulations was introduced in 2008. The company is now providing newly developed product for Photovoltaic Solar or similar domestic micro-generation installations. Wylex has produced an extensive range of dedicated circuit protection equipment thus removing the need for that surfeit of additional enclosures and custom wiring. Having such off-the-shelf products ensures that switching and circuit protection logically conforms to the special considerations needed to protect and manage cables that in this instance have the unusual circumstance of having both a main and generator supply connected at either end. The new Wylex products include AC and DC isolators, combination DC/AC photovoltaic isolators in single enclosures, dual supply photovoltaic and grid mains switches and a complete range of photovoltaic ready 17th edition consumer units with integral generated power supply Isolator and meter.
The benefit of this approach does not just save time and space providing a neater solution. It also helps address particular problems that are encountered in these circumstances, for instance those relating to the isolation of the domestic circuit for the purposes of maintenance or any system extension or modification. With dual supply, there is a danger associated with not ensuring complete disconnection, as only the mains supply and not the generation circuit may be switched by throwing the conventional isolator in the consumer unit. If the micro-generation circuit has been connected by back wiring an mcb, that mcb must also be switched off, even if the inverter powers down at loss of mains supply. This is because the power down is not instantaneous and any auto-reconnection attempt by the inverter will energise the installation, albeit for only a matter of seconds. Extensive labelling is required and may be provided, but cannot compete with a simple single switching operation.
To overcome this, the Wylex range includes a four-pole PV / Mains isolator that will disconnect both circuits simultaneously and also ensures the PV generated connection joins the Mains supply connection at the same point of the installation. There is also a range of dedicated consumer units containing PV and Mains AC isolators, together with mcbs and rcds, for protection of the generating circuit as specified in the regulations, and digital MID meters with traditional analogue or LCD display to measure the generated power output from the inverter. The range is fitted with this additional equipment pre-wired and pre-labelled to simplify and speed up installation with isolators for both circuits sited adjacent to one another and able to be physically linked if required.
Another difficulty is coping with the siting of the circuit protection for the micro-generation circuit. A combi-consumer unit, isolator forms part of the new product range for location at the inverter, as does a load-end isolator, consumer unit and power generation meter, thus accommodating both circuit protection options. This caters for regulations and guidelines that currently ambiguously specify both options.
With any new development, it is always reassuring to see familiarity in the equipment provided for the new application. Here, Wylex has supplied a permanent analogue display “traditional rolling barrel numbers” power generation metering with a similar read out to conventional mains supply meters already installed. There are also familiar combi-consumer units that provide all standard 17th edition options but include prewired isolators and micro generation protection devices in a 19-way enclosure.
It is important to note that all dedicated PV solar equipment has been attributed a lower vat rate that standard electrical circuit protection equipment. This rate has been fixed considerably lower at 5% and can therefore provide a real cost benefit to all VAT registered installers on their final quoted prices. The lower rate even applies to the fitting of any PV Solar ready installation, i.e. the circuit protection equipment used in advance of an active installation. This makes the retrofitting of micro generation simpler in the future. Using off the shelf Wylex PV Solar equipment provides a neat and tidy solution combining a number of components in a single package unit, reducing installation time by reducing wiring. All units are supplied pre-wired and pre-labelled for convenience.
Download the Wylex Solar PV Switchgear Solutions brochure below.