An Analysis of Photovoltaic Performance on Fire Station Buildings in London

This paper presents the performance and financial viability of photovoltaic (PV) installations that have been retrofitted to 8 operating fire stations in London. The study analyzes the theoretical performance of each installation using different methodologies, and compares the actual generation yields against the original modeled data by the design consultants. Performance was evaluated with respect to local conditions for each installation such as orientation, tilt angle and shading. Modeling was carried out using approved industry techniques and software packages to investigate the effects of repositioning and upgrading to more efficient panels to ascertain if better solutions could have been implemented. The analysis has shown that the energy generation was generally in keeping with original predictions of the design consultants, providing some confidence in performance forecasting for this technology. A whole life (installation to decommissioning) net present value (NPV) and Internal Rate of Return (IRR) analysis of the PV installations was conducted, including future inverter replacement and re-roofing costs. This revealed that due to a larger than expected capital outlay (particularly for the inverter replacement), the systems did not produce a commercially attractive return on investment. The study also investigated the effect of applying the UK Feed in Tariff (FiT) for which these systems were not originally eligible which showed that a simple payback could be achieved within the 25 year system lifetime. The FiT therefore offsets some of the risk associated with roof mounted PV systems. The conclusion of the study is that the current PV installations on eight of the London Fire Brigade stations cannot be considered a viable financial investment without the use of a suitable subsidy, and even this does not provide a substantial rate of return due to the high initial capital outlay. However, the forecast energy performance of PV systems using standard industry tools can be reasonably reliable, and that current system pricing suggests that photovoltaic technology can produce a reasonable rate of return.