Introduction to Solar Energy Technology Ilya Chernyakhovskiy, NREL July, 2018
Global Solar Energy Growth 2
Global Solar Energy Growth 3
Technology costs continue to decline
Module costs are coming down Sources: Co pa y figures ased o Q 7 a d pre ious SEC fili gs y the respe ti e o pa ies. Deutsche Bank (07/18/17) 5
Solar prices can be lower than new coal & new gas plants Solar vs. Thermal Plant Price Comparison (2016) Cents/kilowatt hour (USD) 7 6 5 4 3 2 1 0 UAEUAEMexicoMexico- Chile- 2016 Chile- 2016 Chile- 2016 UAE- 2016 Auction- Commodity Hassyan Auction Auction AuctionAuctionAuctionCoal Sept 2016- Sept 2016Solar Natural Gas Coal Solar MarketNatural Gas Solar Natural Gas Power Plant Location and Type 6
Renewables drive job growth 7 7
Solar Energy Systems
ENERGY FROM THE SUN EVERY 15 MINUTES ENOUGH SOLAR ENERGY REACHES THE EARTH TO SUPPLY THE EARTH'S ENERGY NEEDS FOR AN ENTIRE YEAR About 1350 W/m2 (the solar constant) continuously reaches the edge of the earth's atmosphere About 1000 W/m2 continuously reaches the earth's surface at the equator on a clear day Remaining energy is absorbed or reflected by the atmosphere 9
Solar Radiation Some solar energy is absorbed by the atmosphere The clearness index is the ratio of the radiation at the edge of the atmosphere and at the surface of the earth Image source: http://rredc.nrel.gov/solar/pubs/shining/chap2.html 10
Solar Radiation Components Direct normal (beam) o Radiation arrives at collector in direct line from sun Diffuse Radiation scattered by molecules, aerosols and clouds, arrives at collector from all directions of the sky o PV can use both direct and diffuse radiation o Global Radiation = Direct Normal + Diffuse 11
What is Solar PV? Photovoltaic (PV): Photo = light, voltaic = electricity The photovoltaic effect is the conversion of light into electricity Solid-state: no moving parts! A single 1 cm2 cell produces about 1 W at 0.5 V Solar cells produce DC current 12
Cells, Modules, and Arrays Solar cells are interconnected to form modules, which in turn can be interconnected to form arrays 13
Utility-scale solar PV Fixed tilt 1-axis and 2-axis tracking Benefits: o Cost (fixed) o Production (tracking) o Timing (tracking) 14
Distributed solar PV 15
Stand Alone Lighting and Charging Solar panel: 10x10 cm <10 Wp Storage Lithium-ion battery: High energy density: 150-200 kwh/m3 40kWh/ton Low weight: average 7kg, compared to 35kg for lead-acid battery High efficiency: 95-100% Long cycle life: average life >20 years; >3000 cycles at 80% depth of discharge LED lights: High brightness: >200 lumens/bulb, compared to 150 lumen oil lamp Long life: >20 years considering 4hrs/day usage Charge controller: Protects batter from overcharging or discharging and spikes in voltage Protects PV panel from reverse polarity 16
Stand Alone Home System Generation: Solar: average 10-350 W Small wind turbines: typically 1-10 kw with <7m rotor diameter Hydro: typically run-of-river; pico (5-20 kw), micro (<1000 kw), mini (< 1 MW) Diesel: generator of any size Bio ass: ultiple fuels & te h ologies to produ e ele tri ity Can use single resource, hybrid system, or none (batteries only) Storage Batteries - Typically lead acid or lithium ion Typically 100 Ah/12Vdc Wiring and control: depends on configuration of generation and loads Charge controller, 10A/10A/12 V DC Inverter for AC loads or rectifier for DC Meters and/or energy management system to balance generation with battery charge and load 17
Photovoltaics System (Grid Connected) 18
Inverter Residential/commercial inverters Utility-scale inverters Converts Direct Current (DC) to Alternating Current (AC) 19
Influences on Solar Resource Clouds o Geography: mountains, oceans, large lakes Air quality o o o Pollution Natural haze Volcanic activity Altitude Time o o o Diurnal (daily) Seasonal Inter-annual variation (El Nino, La Nina, etc.) 20
Design Consideration: Siting and Shading Minor PV module shading can reduce output dramatically 5.0 50 4.5 45 4.0 40 3.5 35 Isc unshaded 30 Unshaded 2.5 25 I-V 2.0 20 1.5 15 1.0 P-V 10 Shaded 0.5 5 0.0 0 0 5 10 15 Voltage (V) Source: Peter McNutt, NREL Power (W) Current (A) 3.0 20 25 Voc I-V and P-V curves of an unshaded and shaded crystalline-silicon module shading just 7% of the module area yields a 93% drop in its output power! 21
Cloud Variability N Cloud Shadows 25 MW DeSoto Plant 73 hectares Source: Adam Kankiewicz (WindLogics) 22
PV Variability & Geographic Smoothing Aggregate variability of multiple sites is significantly smoother than individual sites Spatially diversifying systems reduces impacts from single weather events to the entire grid Sour e: Mills a d Wiser. I pli atio s of Wide-Area Geographic Diversity for Short-Ter Varia ility of Solar Po er 23
Uncertainty and Variability Variability Source: Sherry Stout, NREL Uncertainty Source: University of Oldenburg; https://www.unioldenburg.de/en/energiemeteorology/research/solar-energy/ 24
Variation by Month 26
Operating and Maintaining PV Systems Periodic module cleaning and inspection Routine inspection and maintenance o o o Clean collector surfaces Support structures Inspection for loose wiring connections and corrosion 27
Thank you 28