Solar PV (Part 1)

Summary

This lecture on solar energy reviews key points, including the amount of solar energy available, optimal angles for solar panel placement, and the functioning of photovoltaic (PV) cells. It discusses how to model and predict PV cell behavior, and how to design systems for maximum solar energy utilization. The lecture highlights the abundance of solar energy, the current global capacity for PV systems, and the decreasing costs of solar technology. It also covers the importance of panel tilting for efficiency and the use of tracking systems to maximize sunlight capture.

Takeaways

• 🌞 The Earth receives a vast amount of solar energy, but due to atmospheric reflection, about 20-30% is sent back to space.
• 📈 Half of the energy is absorbed by the Earth, and the rest is re-radiated in the form of long-wave infrared radiation.
• 🌡 The variation in solar intensity felt throughout the year is due to the Earth's tilt and its orbit around the Sun, causing seasons.
• 🌍 Countries near the equator experience less seasonal variation in sunlight due to their constant proximity to the Sun.
• 🔋 The world's current solar energy generation is 23 terawatts, but with increasing installation of PV systems, capacity is projected to rise.
• 💹 The cost of PV systems is decreasing, with hardware accounting for about half, labor for 10%, and other soft costs for the remaining 40%.
• 🛠️ To optimize solar energy capture, solar panels can be tilted to align with the Sun's rays, which can significantly impact energy intake.
• 📐 The angle of the Sun relative to the Earth can be calculated using the declination angle, which varies throughout the year.
• 🌎 The latitude, declination angle, and altitude are used to determine the optimal tilt angles for solar panels.
• 🤖 Movable trackers can be used to adjust the position of solar panels to maximize sunlight capture, though they introduce additional costs and maintenance.

Q & A

What are the key points discussed in lecture number three on solar energy?

The lecture covered how much solar energy can be harnessed, the best angle for solar energy collection, how PV cells convert solar energy into electricity, modeling and predicting PV cell behavior, combining PV cells into panels and arrays, and designing systems for maximum sunlight utilization.

How much solar energy does the Earth receive and what factors affect this?

The Earth receives a significant amount of solar energy, but around 20-30% is reflected back to space due to the atmosphere. Approximately 50% is absorbed by the Earth. Seasonal variations in solar intensity are due to the Earth's tilt of about 23.45 degrees, which affects the angle at which sunlight hits the Earth.

Why do countries near the equator experience less seasonal variation in solar energy?

Countries near the equator experience less seasonal variation because they are always close to the sun due to the Earth's tilt, resulting in a more consistent amount of sunlight throughout the year.

What is the current global capacity for solar energy generation and what is the trend?

As of the end of the year mentioned in the lecture, the global installed PV power capacity is expected to reach 321 gigawatts. The trend shows an increase in the installation of PV systems, and the cost of solar energy is becoming cheaper over time.

What is the cost breakdown for PV systems, and how has it changed?

Around half of the cost of PV systems goes to hardware, 10 percent to labor, and the remaining 40 percent to soft costs like equipment procurement, engineering, and construction overhead. The cost is decreasing rapidly.

How does the angle of a solar panel affect the amount of solar energy it can capture?

Tilting the solar panel so that sunlight is perpendicular to the panel's surface can maximize energy intake. Even small differences in angle can significantly affect the energy captured, especially in large-scale installations.

What is the significance of the Earth's axial tilt in relation to solar energy collection?

The Earth's axial tilt of 23.45 degrees is significant because it determines the angle at which sunlight strikes the Earth, affecting the intensity and distribution of solar energy throughout the year.

How can the angle of the sun be calculated for optimal solar panel positioning?

The angle of the sun can be calculated using the declination angle, which varies throughout the year. This can be done using the equation provided in the lecture, considering the latitude, day number, and other factors.

What is a movable tracker and how does it help in maximizing solar energy collection?

A movable tracker is a system that adjusts the position of solar panels to follow the sun's movement throughout the day. This can help in capturing the maximum amount of sunlight, although it requires additional components like motors, which can wear out over time.

How does the Earth's tilt and its orbit around the sun affect the solar energy potential in different regions?

The Earth's tilt and orbit cause different regions to receive varying amounts of sunlight depending on the time of year. This results in higher solar energy potential in regions closer to the equator and seasonal variations in higher latitudes.