Solar Energy

This course was written in collaboration with Lee Weinstein. Lee earned his Ph.D. in Mechanical Engineering at MIT, where he conducted research in solar thermal energy generation

In this course we'll examine the principal methods of harvesting energy from sunlight—concentrated solar power and photovoltaic cells—starting from fundamental physics principles.
By the end of this course, you’ll be able to answer practical engineering questions surrounding multi-junction cells, materials design, and considerations in servicing utility scale electrical grids.

• Introduction: Here we learn about the importance of solar energy on Earth and the bedrock science needed to understand it.
• The Essential Energy of Sunlight: Almost all energy on Earth is old sunlight stored for different amounts of time.
• EM Basics: The basic anatomy of solar radiation and how it spreads through space.
• Quantum Light: Enter the Photon: A photon's energy content is determined by its wavelength.
• Spectral Properties of Sunlight: 30% of the Sun's photons carry 50% of its energy to Earth.
• Solar Availability: Take a quantitative look at how much sunlight reaches Earth and explore how we can concentrate sunlight to higher intensity.
• Solar Availability: Just how much energy makes it from the Sun to Earth's surface?
• Solar Intensity: Light beam intensity puts fundamental limits on what we can power with the Sun.
• Conservation of Etendue: Just because you want to squeeze light beams together doesn't mean that you can.
• Directionality of Sunlight: How much energy you can collect from sunlight depends on where you are and what time it is.
• Solar Thermal Power: A close look at concentrated solar power, a flexible collection mode that enables solar power at night.
• Solar Thermal Basics: Can you heat your home at night with sunlight from the day?
• High-Temperature Solar Thermal: You don't need a solar panel to harvest solar energy.
• Efficiency of Solar Thermal Systems: If you want to get the most from solar thermal, you need to make things hot.
• Spectral Selectivity: Careful design of thermal properties can drastically reduce our losses.
• Performance of Spectral Selectivity: Not all absorbers and emitters are created equal.
• PV: Working Principle: An introduction to solid state photovoltaic cells and the physics that enables their production of power.
• What Are Photovoltaics?: An overview of how photovoltaic panels turn sunlight into electricity.
• Band Gap: If you're an electron in a semiconductor, you're either bound to an atom or you're conducting.
• Photon Absorption: A solar cell can't harvest the energy from any old photon, it has to be just right.
• Recombination: When an electron and a hole recombine, useful energy turns into wasted heat.
• Collecting Charge Carriers: Once a photon boosts an electron, it's a race to get its energy before recombination does.
• Doped Semiconductors: A little impurity goes a long way to tune the electrical properties of a semiconductor.
• Current in Illuminated p-n Junctions: The microscopic physics of how sunlight drives current through photovoltaic cells — no-holds-barred.
• IV Curve: Understand the Ohm's law of photovoltaic solar cells.