The introduction of Feed-in-Tariffs (FiTs) has meant that the adoption of photovoltaic (PV) power generation has become more financially viable for many building operators. With this in mind, it is important to remember that a PV installation is not just about the solar panels. Ian Langeveld of Wieland Electric explains.
Despite the fact that installing PV technology is clearly a smart move, until recently the payback figures just didn’t stack up due to the cost of the PV panels. However, since the introduction of the Feed-in-Tariffs (FiTs) in April last year, this situation has changed as energy companies now pay for electricity generated from renewable sources. These payments range from 29p to 41p per kWh of power generated. The tariffs apply to all types of buildings and even open spaces, (although it should be noted that this situation may change for larger scale projects as a result of a recent government review of FiTs).
As a rule of thumb, it has been calculated that rather than a 20+ year payback that could be expected before the introduction of FiTs, a relatively small 25kW installation will return the investment within six years.
Plus, there are other factors to be taken into account, such as the Carbon Reduction Commitment Energy Efficiency Scheme (CRC), which is going to penalise large energy users heavily for use of fossil fuels. And, of course, there are other environmental imperatives, such as a company’s commitment to becoming more sustainable.
So it’s hardly surprising that demand for PV systems is increasing rapidly and analysts have predicted that the UK will have around 250MW of installed PV by the end of 2011, compared to 22MW in 2009.
Cost effective installation
The choice of PV panels is of course vital. However, just as crucial is the need to be aware of the impact that connections and other components can have on the overall efficiency of the system and the speed and ease of installation.
The typical scenario for a PV installation is to connect all of the solar panels in series, taking the combined DC power generated by the array in a ‘string’ back to an inverter for conversion to AC for use in the user’s premises or export to the national grid. There will also be a disconnection switch for maintenance that needs to be included in the set up. So, there are plenty of time consuming connections to be made and anything that speeds things up will reduce installation costs, disruption and time spent working at height.
In this respect it makes sense to apply the principles of ‘plug and play’ wiring that have already proved popular in many other applications. For example, it is now possible to get pre-wired plugs and sockets that will fit the standard connectors supplied with the PV panels.
Here, the method of connection is very important and experience shows that a precision machined connector with the ability to handle up to 40A will deliver the best connections. Another consideration is the material used for the connection, in terms of maximising power generation. Silver plated connectors will reduce resistance losses, compared to standard tin plated connectors.
AC streamlining
While plug and play connectivity is quite well established on the DC side, this is not yet the case on the AC side. Here, installers are still required to adopt time consuming hard wiring of connections from the inverter back to the distribution board. Yet it has already been established that the benefits of modular wiring systems, described previously for the DC side, can also be reaped on the AC side. If inverters and disconnect switches, and perhaps even the distribution boards themselves, are pre-wired with connectors, the whole electrical connection time can be reduced by up to 20%, depending on the size and configuration of the installation and the site conditions.
Plus there are all the benefits of using pre-tested assemblies, so that on-site problems are avoided and less time is spent in tracing and correcting faults.
It also makes sense to take advantage of the latest technologies that are now coming onto the market for other elements of the system. These include PV connectors and junction boxes, overvoltage/lightning protection and solar AC distribution units, all of which can be sourced from a single supplier to ensure compatibility and simplify the procurement process.
From experience with other ‘new’ technologies it’s clear that the success of the early projects will have a strong influence on future uptake and the benefits that accrue. In the case of PV, ensuring that this technology delivers maximum benefits is of paramount importance.
