Oxford 5 th April 2006 Integrating a large solar array to enhance the performance of a low energy building. Keith Tovey ( 杜伟贤 ) M.A., PhD, CEng, MICE HSBC Director of Low Carbon Innovation: and Charlotte Turner: School of Environmental Sciences CRed

The ZICER Building The Solar Arrays Performance of PV Issues of Shadowing Electrical Integration Some Observations on Solar Thermal Integrating a large solar array to enhance the performance of a low energy building.

Zuckerman Institute for Connective Environmental Research (ZICER) Part of the School of Environmental Sciences A World Renowned 5** Research Department: Excellent Teaching Rating Includes –Tyndall Centre –Centre for Social and Economic Research into the Global Environment –Centre for Environmental Risk –Climatic Research Unit –Low Carbon Innovation Centre 65 faculty, 145 Researchers, 200 Research Students, over 50 Postgraduate Students on taught courses and nearly 400 undergraduates.

ZICER Building Heating Energy consumption as new in 2003 was reduced by further 50% by careful record keeping, management techniques and an adaptive approach to control Low Energy Building of the Year Award 2005 awarded by the Carbon Trust.

ZICER Building One of 7 Low Energy Buildings at UEA One of 5 using Termodeck construction Integrates Photovoltaic cells into initial design –6.7 kW on top floor of façade –~27.2 kW on roof

Two large open plan offices: Note: extensive use of computers Significantly more than originally planned – meant that target of PV generation was not reached

Top floor is an exhibition area – also to promote PV Windows are semi transparent Mono-crystalline PV on roof ~ 27 kW in 10 arrays Poly- crystalline on façade ~ 6/7 kW in 3 arrays ZICER Building Photo shows only part of top Floor

ZICER Building PV performance Façade (kWh)Roof (kWh)Total (kWh)

Performance of PV cells on ZICER Note: East Anglia mean solar radiation is just 1100 kWh per year – in many places in world it is as high as 2000 kWh even at similar latitude Only 1/10 th of output on cloudy summer day

Load factors Façade: 2% in winter ~8% in summer Roof 2% in winter 15% in summer Output per unit area Little difference between orientations in winter months Performance of PV cells on ZICER

All arrays of cells on roof have similar performance respond to actual solar radiation The three arrays on the façade respond differently Performance of PV cells on ZICER - January Radiation is shown as percentage of mid-day maximum to highlight passage of clouds

Orientation relative to True North

Arrangement of Cells on Facade Individual cells are connected horizontally As shadow covers one column all cells are inactive

Arrangement of Cells on Facade Individual cells are connected vertically Only those cells actually in shadow are affected.

Performance of PV cells on ZICER

Actual Situation excluding Grant Actual Situation with Grant Discount rate 3%5%7%3%5%7% Unit energy cost per kWh (£) Avoided cost exc. the Grant Avoided Costs with Grant Discount rate 3%5%7%3%5%7% Unit energy cost per kWh (£) Grant was ~ £ out of a total of ~ £ Performance of PV cells on ZICER Cost of Generated Electricity

Performance of Photo Voltaic Array Inverters are only 91% efficient Most use is for computers DC power packs are inefficient typically less than 60% efficient Need an integrated approach

Solar Energy - The BroadSol Community Project Annual Solar Gain kWh Solar Collectors installed 27th January 2004 Performance when there was snow on ground Store temperature was at base of tank

Normal hot water circuit Solar Circuit Solar Pump Efficiency of increases with increased day time use of water Efficiency increases with significant hot water use late in evening Efficiency decreases with significant hot water use early in morning Need for new intelligent self learning Hot Water Control Systems Optimum orientation is 10 – 20 degrees west of south

Conclusions Economics of PV was only viable on ZICER because of Grant Shading has some effect on façade, but improvements could be made by different method of wiring cells Overall Load Factor is 7.6% with 8.3% on roof and 4.7% on façade. In summer Load Factor can reach 15%. 9% of electricity is lost in inverters, and a further 50 – 60% is lost in IT equipment. Need to consider an integrated approach – possibly with DC networks in similar buildings. Need for integrating behavioural use in design on control of solar thermal systems. Keith Tovey ( 杜伟贤 ) M.A., PhD, CEng, MICE HSBC Director of Low Carbon Innovation: and Charlotte Turner: School of Environmental Sciences CRed