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Solar Energy Opportunities Seminar by N.K. Tovey

Discover solar thermal and photovoltaic technologies, integration challenges, and life cycle issues at the Renewable Energy Seminar on March 1, 2011. Keynote speaker N.K. Tovey shares insights on maximizing these technologies' performance in buildings.

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Solar Energy Opportunities Seminar by N.K. Tovey

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  1. CLA Renewable Energy Seminar 1st March 2011 Solar Energy Opportunities N.K. Tovey (杜伟贤) M.A, PhD, CEng, MICE, CEnv • Solar Thermal • Solar Photovoltaic • The performance of these technologies • The challenges of integrating solar energy into • buildings to make most effective use of the resource. • Life Cycle Issues Recipient of James Watt Gold Medal for Energy Conservation 1

  2. A Partnership between Broadland District Council University of East Anglia Launched by publicity with an open meeting attended by ~120 Aims To promote Solar Water Heating by a community to enable bulk discounts Required a minimum of 50 participants to sign up within 3 weeks Over subscribed in 22 minutes! Subsequently 9 properties not found to be suitable To develop skills for installing Solar Hot Water Heaters in the region Technical Opportunities: Solar Thermal: The Broadsol Project

  3. Solar Thermal: The Broadsol Project Solar Collectors installed 27th January 2004 Annual solar collection 750-910 kWh/annum

  4. Technical Solutions: Solar Thermal Energy: Performance

  5. Technical Solutions: Solar Thermal Energy Up to 15 installations were monitored at 5 minute intervals for periods up to 15 months Mean Monthly Solar gain for 11 systems 3 panel systems Some 2 panel systems captured twice the energy in summer months as other 2 panel systems.

  6. The Broadsol Project • Three panel systems captured only 13% more energy compared to two panel systems • Effective use is not being made of surplus in summer

  7. Measured Overall System Efficiencies – including storage 2 panel 3 panel System Efficiency of 2 panel systems is generally higher than 3 panel systems

  8. Solar Thermal: Performance of Panels Tilt Angle variations are not significant in region 0 – 45o in summer In winter optimum angles are between 45o and 90o Optimum orientation in East Anglia is SSW South West is almost as good as South 8

  9. More Solar Energy is Collected when Hot Water use is greater. Sky became hazy at ~ 11:00 Substantial hot water demand at 13:30 Normal heat loss from tank if there had been no demand shown in black 1.157 kWh extra heat collected. Note: further demand at 18:30 leading to further solar collection. Even more solar collection would have been possible had collector been orientated SW rather than S 1.164kWh 0.911kWh 1.157kWh 0.083kWh BS27: 15/05/2004 9

  10. Technical Issues requiring awareness raising: Solar Thermal Energy captured when combined with central heating • Tank with small residual hot water at top of tank in early morning • If Central Heating boiler heats up water – less opportunity for solar heating. Zone heated by solar energy

  11. Technical Issues requiring awareness raising: Tank with small residual hot water at top of tank in early morning No hot water provided by central heating boiler. Gain from solar energy is much higher. More solar energy can be gained if boiler operation is delayed. Boiler ON/OFF times should be adjusted between summer and winter for optimum performance

  12. The Broadsol Project: Store Temperature Variations Day 1 Day 2 Education of how to get best out of solar HW systems is needed. Need to adjust timing of central heating boiler over late Spring, Summer and early autumn. • On day 1, if boiler supplied hot water before solar gain was sufficient, top of tank would be heated to 55o C and reduce the potential solar gain by ~21%. • On day 2, the loss would be negligible as temperature at top was already over 55oC. • If the store temperature throughout was as low as 20oC having been drawn off for a bath late on previous evening the loss in potential solar energy gained for having early operation of the boiler can approach 40%.

  13. Solar Thermal: The Renewable Heat Incentive The last Government announced a Renewable Heat incentive which would be beneficial for Solar Thermal Installations and provide a financial incentive. Thus small scale (<20kW) solar thermal would potentially benefit owner by 18 p per kWh and last for 20 years. In the Comprehensive Spending Review the Government indicated it is still committed to such an incentive and is due to bring forward its plans within the next month.

  14. Technical Solutions:Solar PhotoVoltaic Zuckermann Institute for Connective Environmental Research. (ZICER) Low Energy Building of the Year 2005. Has heat demand ~ 20% of building of its size: 34 kW of Solar Photovoltaic on roof and facade

  15. Solar Rosette Diagram for East Norfolk/Suffolk 0 30 60 90 120 150 180 210 240 270 300 330 360 N NE E SE S SW W NW N Azimuth

  16. ZICER Building Photo shows only part of top Floor • Mono-crystalline PV on roof ~ 27 kW in 10 arrays • Poly- crystalline on façade ~ 6.7 kW in 3 arrays

  17. Peak Cell efficiency is ~ 9.5%. Average efficiency over year is 7.5% Actual Efficiency of PV Cells Poly-crystallineCell Efficiency Mono-crystalline Cell Efficiency • Peak Cell efficiency is ~ 14+% and close to standard test bed efficiency. • Most projections of performance use this efficiency • Average efficiency over year is 11.1% Inverter Efficiencies reduce overall system efficiencies to 10.1% and 6.73% respectively

  18. Performance of PV cells Output per unit area Little difference between orientations in winter months Load factors • Across UK average load factor is 9 – 11% based on analysis of ROC data 2009 – 2010. • i.e. if system is 1kW peak the average annual output will be • ~ 0.1* 1 * 8760 = 850 kWh • However, solar radiation does vary by +/-30% for one year to next.

  19. 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 19

  20. 120 150 180 210 240 Orientation relative to True North 20

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  22. Way in which cells are connected must be considered. Arrangement of Cells on Facade Individual cells are connected horizontally Cells active Cells inactive even though not covered by shadow If individual cells are connected vertically, only those cells actually in shadow are affected. As shadow covers one column all cells are inactive

  23. Solar PhotoVoltaic: Technical Solutions: Integrated use of PV generated energy • Inverters are only 91% efficient • Computers and other entertainment use DC. Power packs are inefficient • LED lighting can use DC • Need an integrated approach – houses with both AC and DC with heat recovery from central inverter/rectifier?

  24. Feed in Tariffs – Introduced 1st April 2010 On February 7th 2011, Chris Huhne announced that there would be an urgent review of PV schemes this year > 50 kW prior to the scheduled review next year – with the likelihood that such schemes would not be eligible for FITs. However, he did state “The Government will not act retrospectively and any changes to generation tariffs implemented as a result of the review will only affect new entrants into the FITs scheme. Installations which are already accredited for FITs at the time will not be affected.” - implying at even if the degression rate is increased – those already on the scheme will not be affected.

  25. Feed in Tariffs – Export and Issue of Deeming Payment for tariffs will be from a levy on Utility Companies which MAY see a cumulative rise in bills of around £1 billion or more. In addition there will be a payment of 3p per kWh for any electricity exported as opposed to consumed on premises. BUT an export meter is needed to identify this. Householder will save on imported electricity at ~ 10 – 12p per kWh, so optimum financial model may not be to generate as much as possible i.e. for each unit generated and consumed it is worth 41.3+ 12 = 53.3p /kWh for each unit exported it is worth 41.3 + 3 = 44.3 p/kWh If no export meter is fitted – a transition arrangement of deeming that 50% of generation will be exported will be made - that may well not be as attractive to consumer.

  26. Life Cycle Issues for PV Array on ZICER Building Carbon Factors for Electricity Production Spain ~ 0.425 kg / kWh UK and Germany ~ 0.53 kg/kWh

  27. Solar Thermal Installations can reduce energy requirements for hot water. But careful consideration of timing of normal hot water system is needed for optimum performance. Solar PV systems Need care in design to ensure optimum performance. Consider integration of use via INTERNAL DC networks to avoid unnecessary losses. The new Feed in Tariffs should help economics, but optimum returns will come for early adopters. However: The effective cost to society to reduce 1 tonne of CO2 in a small scale system is over £700 tonne < £100 per tonnefor onshore wind ~ £20 per tonnefor cavity insulation Solar Energy Possibilities: Conclusions

  28. And Finally “If you do not change direction, you may end up where you are heading.” LaoTzu (604-531 BC) Chinese Artist and Taoist philosopher N.K. Tovey (杜伟贤) M.A, PhD, CEng, MICE, CEnv k.tovey@uea.ac.uk • This presentation will be placed on the Internet from tomorrow at: http://www2.env.uea.ac.uk/cred/creduea.htm

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