Solar so good
The Energy in Buildings Directive has stepped up a gear, with the requirement this year for all public buildings to visibly display their energy performance certificates. This is of course a prelude to the initiative being rolled out and implemented across all commercial buildings, both public and private, above and below 1,000m2.
Further pressures from local government mean planning authorities are demanding developments which take carbon reduction measures seriously and large commercial and public sector organisations are also bound by the Carbon Reduction Commitment that demands a cut in carbon emissions of 1.1 megatonnes of carbon each year.
But making carbon reductions and saving energy costs is not just about the use of energy once it enters a building; in this age of increasing energy price hikes, and ensuing uncertainty for the future, another issue that needs to be tackled is the way energy is brought into the building. A common area of much interest at the moment is the onsite generation of power for a building. In so doing the organisation is able to wholly or partially bypass the national grid, saving on the cost of buying the energy in the first place. One of the most popular areas, and proven to date to be the reliable option, is solar photovoltaic (PV) power.
Harnessing the incredible power that the earth receives from the sun everyday, solar photovoltaic technology works by transforming the energy of the sun’s rays, the photons of light, into electricity. This electricity can then be used in and around the building in the same way as standard electricity from the national grid. PV technology is best deployed on the roof of a building, where it stands to gain the most light, especially when installed on any south-facing roof.
Because a PV system has no moving parts it requires virtually no maintenance. This ‘fit and forget’ option doesn’t even need to be cleaned, as the natural occurrence of rainfall will wash the panels and remove any dust or debris – so keeping the PV cells working to their optimum performance. Similarly, due to the lack of complicated moving parts, solar PV technology is a silent and unobtrusive way of generating electricity, with a guarantee of 25 years and life expectancy of 60 years.
Reliability is often mooted as a reason for refuting solar PV in favour of other forms of onsite generation. However, as a very low risk technology with no ongoing engineering costs associated with servicing, unlike all other renewable options the longevity and reliability of PV is actually one of its key strengths.
Of course, the primary consideration for any organisation which is already looking at renewable forms of energy has got to be cost, and with this the lifetime cost and payback period of any installation, solar or otherwise. Calculating the conventional payback time of a PV system depends on the comparative price of energy at the time of the calculation. However, a Carbon ROI represents a net yield of around 3%, not including a rise in energy prices, making this an obvious and sound choice.
There is still a common misconception that electricity providers do not support PV. However, Scottish & Southern Energy currently pays 18p for every unit of electricity that is fed into the national grid. Where energy is generated, and not used within the building, it is automatically exported to the grid. Recognising the advances Europe has made, with realistic (and attractive) feed-in tariffs, the Conservative party recently announced its own feed-in tariff policy too, which if implemented, would bring the UK on a par with solar PV users across Europe such as Germany.
Cost, initial outlay and payback periods aside, there are other factors that supplement the upfront costs of a solar PV system making it an attractive option. Future-proofing the organisation against further energy price rises is the tip of the iceberg. Further benefits can be found in the visibility that solar PV provides for a corporate responsibility positioning campaign. The presence of the visible effort a company is making to improve its environmental credentials can be used as a platform from which to tell its markets about such initiatives. Internally there is the boost to morale, which is derived from the monitor provided with the system, which clearly displays how much electricity is being generated in real-time, as well as the cumulative volume of carbon that has been saved as a result.
Commercial developer Gazeley is a strong supporter of solar PV. The organisation’s commitment to eliminating its carbon footprint is the focus of its work with various companies across the sustainability and renewables sector. Solarcentury’s SB720 system has been used at one of the latest developments in Bristol to make a significant reduction in the amount of CO2 the process has produced.
With no structural upgrades required to the roof, the entire system was installed in two days by only a two-man team.
The new thin film PV modules incorporated in the SB720 means the system yields 4% more electricity than with standard modules. For a 7.2 kWp system this amounts to over three additional tonnes of CO2 emissions offset over the unit’s 25 year guaranteed generation period. In total the system will generate 6484 kWh of electricity per year, saving 100 tonnes of CO2 emissions over 25 years.
The government is beginning to take note of the need to support renewable technologies, and their incorporation in both new and existing buildings. The Low Carbon Buildings Programme provides grants to cover up to 50% of the cost of an onsite microgeneration scheme to all local authority organisations. This includes schools, colleges, and any other non-profit making organisations.
One organisation to take advantage of this is the estate of the London Fire Brigade, run by the London Fire and Emergency Planning Authority. To date Solarcentury has supplied solar PV systems to eight London Fire Brigade (LFB) stations. The installation of solar PV is contributing to the LFB being ever closer to reaching a target of reducing its carbon emissions by 1,900 tonnes by 2010.
Richmond Fire Station is one of the LFEPA’s sites that is benefiting from a solar PV installation. The solar PV installation on the fire station is spread over three distinct areas: the roof windows, a flat roof and a pitched roof. The pitched roof consists of 48 Sanyo 190W PV modules supplied by Solarcentury. This covers a total area of 57m2, capable of producing a total peak DC power of 9.12 kilowatts.
There are 32 Sanyo 190W PV modules supplied by Solarcentury installed on Richmond Fire Station’s flat roof area. The modules are installed on a framework on the flat roof to hold them at the optimal angle for capturing daylight. The total surface of the array is 38m2, and it is capable of producing a total of 6.08kWp.
The roof windows have been installed with 24 80W PV glass-glass laminates (GGL). The peak power of the GGL in the skylights is 1.92kWp, with a surface area of approximately 38m2.
In total the entire installation is capable of producing a total peak DC power of 17.12 kilowatts under Standard Test Conditions. The total estimated annual energy yield for the array is 11,490 kilowatt hours, and it is projected that the system will save 6,526 tonnes of carbon per year for the station.
Energy consumption and the need for electricity is core to any business function. However by addressing the need to reduce carbon emissions organisations stand to gain significantly from their commitment to reducing bottom line energy costs as well as addressing CSR. Solar photovoltaics offers a cutting edge and sustainable method of generating clean onsite electricity, offsetting electricity that would otherwise have been used from the National Grid, and cutting carbon emissions.