PV Hybrid Systems and Minigrids

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1 PV Hybrid Systems and Minigrids Georg Bopp, Fraunhofer Institute for Solar Energy October 13th, 2015 Praia, Cap Verdes

2 Fraunhofer Institute for Solar Energy, Freiburg, Germany Performing Research for the Energy Transformation, 1300 employees, 12 Business Areas Energy Efficient Buildings Silicon Photovoltaics III-V and Concentrator Photovoltaics Dye, Organic and Novel Solar Cells Photovoltaic Modules and Power Plants Solar Thermal Technology Hydrogen and Fuel Cell Technology System Integration and Grids Electricity, Heat, Gas Energy Efficient Power Electronics Zero-Emission Mobility Storage Technologies Energy System Analysis Seite 2

3 Activities for Autonomous Systems and Mini Grids Pico-PV, Solar Home Systems, Technical Systems, PV Hybrid Systems, Mini Grids System Design, Optimisation and Evaluation Development of Components, Energy Management Systems, Battery Management Systems, Operating Strategies Simulation studies and analysis Demonstration Projects System Monitoring and Quality Assurance Training of the planning, installation, operation and maintenance staff Contact: Georg Bopp, 0049/ Seite 3

4 Fraunhofer ISE examples of PV Hybrid Systems and Mini Grids Alpine huts in German Alps About 30 systems realised ( ) Planning, maintenance, evaluation, optimisation 1 17 kw p PV, 5 25 kw Diesel 1 20 kw Inverter, kwh Battery Most systems still running with modifications Village supply with Mini Grids in China PV Hybridsystem, Rotwandhaus, German Albs Technical Monitoring of 12 systems ( ) financed by giz Conception of the monitoring system Training of the local staff in installation and evaluation Evaluation Now most systems out of operation because lack of responsibility and grid extension Mini Grid, Qinghai, China Seite 4

5 Approach for system planning and realisation talk with users on requirements, needs and wishes decision on system concept together with the user evaluation of energy consumption and realisation of energy saving strategies together with the user. dimensioning of the system (use e.g. PVsol, Retscreen, Homer, ) definition of system and operating concept sizing and selection of components (efficiency, reliability, costs) regarding standard on electrical safety and basic rules on lightning protection installation of the system acceptance check of the system introduction of the user to the system organisation of regular maintenance and repair of systems Seite 5

6 System concept with DC coupling of generators and battery Market Development PV generator charge regulator wind turbine battery charger storage battery inverter house grid motor generator battery charger Image: Fraunhofer ISE, Freiburg, Germany; Solarpraxis AG, Berlin, Germany Seite 6

7 System concept with AC coupling of generators and battery PV generator inverter AC loads charge regulator wind turbine battery motor generator Image: Fraunhofer ISE, Freiburg, Germany Seite 7

8 3-phase AC-coupled PV Hybrid System Image: SMA Technologie AG, Niestetal, Germany Seite 8

9 DC/AC coupling: Advantages and Disadvantages DC coupling AC coupling + Only one conversion for battery charging + A lot of different manufactures and products available + Higher system efficiency for mainly night based energy demand + Only one conversion for AC supply + Higher system efficiency for mainly day based energy demand + Power extension easy + Standard AC Installation + lower prices if PV > 20 kw -Two conversions for AC supply - power extension not easy - Lower system efficiency for mainly day based energy demand - Two conversions for battery charging - Lower system efficiency for mainly night based energy demand Seite 9

10 First goal: Minimisation of electric power consumption by introducing energy saving appliances Important tasks for reducing electric power consumption LED (or compact fluorescent lamps) for lighting use of appliances with energy saving class A + + (+) (lists available in Internet or consumer councils), the electric power consumption is about 3 times lower in comparison to poor appliances warm water supply for dish washer and washing machine use solar collectors for preparing of hot water power limitation e.g. for heat power of washing machines Seite 10

11 To get a clear picture of the loads the following is necessary Visit the households, Communicate with the people Ask the people on their actual energy demand and which energy sources they use Try to find out the day to day rhythm of their life Look around to see which appliances are already there Try to figure out the future needs of the people Seite 11

12 Power and energy calculation (20 households) Load Quantity Power (W) Average Daily Hours Concurrency (same time) Adjusted Peak Power (W) Daily Consumption (kwh) I II III IV =I*II*IV =I*II*III Energy Saving Lights TVs , Recorders/VCDs Washing Machines Refrigerators Water Pumps 1 1, , Others Total 4, Average electric power consumption for rural households ~ kwh / day Average electric power consumption for Cape Verde households ~ 3 kwh / day Average electric power consumption for Germany households ~ 10 kwh / day Seite 12

13 Daily Power / Energy Consumption Growth (1000 Households) Peak Power Growth (kw) Daily Energy Consumption Growth (kwh) (Gaize, Tibet) Calculate approximately 10 % growth per year Seite 13

14 Micro Power Manager for Mini Grids Prepayment meter which limits electric power and energy consumption with respect to the contract and the availability of resources German source Seite 14

15 Reliability and maintenance efforts Fully operational PV systems are state of the art! In the past and if you build your first system: average number of faults per year: 2 Steadily increasing reliability of components such as inverters and charge controllers result in decreasing number of faults as any other technical device or systems PV systems need regular maintenance approx. one working day per anno for regular maintenance for systems with bigger than 3 kwp PV generator approx. one additional day for very complex hybrid systems or very remote locations Reduction to one fault every 2-3 years is realistic additional maintenance effort for diesel and wind generator! Seite 15

16 Non-technical aspects relevant during planning and operation of Mini Grids Energy allocation concepts and energy consumption controls are necessary installation of suited accounting systems Training of users to increase acceptance for the systems and to make familiar with limited resources installation of a management structure for a sustainable and economic operation Image: Fraunhofer ISE, Freiburg, Germany Taking into account local structures and cultural habits Seite 16

17 Mini Grids: Substitution of Diesel generators with PV Life cycle cost analysis Example Mexico 99 households, a rural clinic and a fish factory Daily consumption: 2849 kwh Peak load: 200 kw Variation of PV module prices [5.50, 2.00, 1.00 USD/Wp] [$/ kwh] Levelised Energy Cost (LEC) for different Mini-Grid-Systems 0,8 Total LEC [5,5USD/Wp] Total LEC [2USD/Wp] Total LEC [1USD/Wp] 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0,0 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Solar share Seite 17

18 Integration of PV and/or Wind into existing Diesel grids for islands, village supply, irrigation, industry, mining,,.. Integration of PV very interesting because PV price low and no battery necessary The manufactures promise high diesel savings Is this possible and true? Because the diesel generator needs a minimum load of % A fuel saver which cap PV or wind power is necessary. For Cape Verde wind farms this result in unused energy of ~ 50% Savings strongly depend on load profile, availability of shift able loads, forecast quality Higher savings with advanced motor control like cylinder cut off and fuel cut but needs further research and development Higher savings with integration of battery Fraunhofer ISE can evaluate this by own system simulations and optimizations Seite 18

19 l l l l Diesel savings by PV for Egypt industry and Greek Island Egypt industry: Peak load 420 kw, yearly diesel consumption without PV liter Seite 19

20 Innovativ integration of PV into diesel irrigation system Direct DC coupling of PV simple Possibility of retrofit Higher diesel saving, because diesel Frequency converter necessary Frequency converter must be able to do Maximum Power Point Tracking for PV Fraunhofer ISE can support you can be stopped ~ = Frequency converter Seite 20