Solar Energy in a Nutshell (Solar Energy Course 2020 Part 12 of 12)

Solar Energy in a Nutshell (Solar Energy Course 2020 Part 12 of 12)


This video is part of iPolytek’s online course
on solar energy. iPolytek, Professional Development Courses
for Engineers. At the beginning of this course, we set out
to answer 6 questions on solar energy. Here’s a summary of what we learned. What is the role of solar PV in the global
energy supply today? What will be its role in the future? At the end of 2018, photovoltaics accounted
for 2.4% of the world’s electricity production. In total, solar PV produced 505 Gigawatts
worldwide. The International Energy Agency (IEA) predicts
that solar photovoltaics will contribute about 16% of the worldwide
electricity supply by 2050. According to The Fraunhofer Institute for
Solar Energy Systems , “Between 2030 and 2050, we will see 10-30% of global energy demand
covered by solar PV (photovoltaics). Right now we are
in an embryonic state compared to where we are going in a few decades” How does solar energy compare in magnitude
with other sources of energy? According to a study conducted by The International
Energy Agency (IEA) the Worldwide Demand for Energy in 2015 was
18.5 TWy/y. This is eclipsed by the 23 000 TWy/y of Solar
Energy that falls on the surface of the Earth. The combined total of all other renewables doesn’t even come close to solar at 156.3 TWy/y. Even the combined total of all non-renewable
reserves doesn’t even come close at 1570 TWy. Overall, we can see that the energy we receive
from the sun each year is: • more than 1240x the annual global energy
demand • about 150x greater than the possible annual
output of all other renewable energies • and about 15x the total of all non-renewable
energy reserves How do solar cells produce electricity? A photon is absorbed by the solar cell. Its
energy is given to an electron in the crystal lattice. This energy excites an electron from the P-type
silicon and “kicks” it into the conduction band where it is free to move around within the semiconductor. When the electron exits the P-type silicon,
it leaves its place empty. creating a “hole”. An electron from a neighbouring atom moves
into the “hole”, leaving another hole behind. In this way, holes are propagated throughout
the lattice. As this happens, electricity begins to flow
in the circuit that the solar cell is connected to. Ideally, a photon with an energy equal
to that of the bandgap hits the solar cell and excites an electron from the valence
band to the conduction band since the “surplus energy” is transformed into heat. How efficient are solar cells today? Today, there are 3 generations of solar cells.
# 1: Crystalline Silicon # 2: Thin film
and # 3: Emerging PVs Efficiencies across the three generations
vary between 10% and 46%. 1st generation mono and multi-crystalline
solar cells have an average efficiency of 23%. 2nd generation thin-film solar cells have an efficiency of 18%.
3rd generation printable solar cells have an efficiency of 10%,
whereas 3rd generation solar cells with concentration or multijunctions have an efficiency ranging
from 25 to 46%. How do you size a solar photovoltaic system? Step 1. Calculate the required PV power generation
based on • the annual energy consumption of the load
and • the number of peak sun hours per day at
1000 W/m2 based on tables and maps available online for this purpose. Step 2. Take into account the losses found
in the overall system, including those due to the conversion of direct current
into alternating current.
• Correct the required PV power accordingly • In general, the correction factor (derating
factor) is between 0.6 – 0.75. Step 3. Choose a module. Correct Pmax of the
module (measured at 25 Celsius to the actual operating temperature.
• Use the Pmax Temperature Coeffcient specified by the manufacturer
• Use the actual operating temperature at the site or, if not
available, the Normal Module Operating Temperature (NMOT)
shown in the specifications of the module. The power output of a solar module can be
estimated using the following formula: where
delta T : temperature increase compared to standard conditions,
STC (25 degrees C) a : Temperature coefficient Pmax [%/C] Step 4. Calculate the number of modules required Number of modules=PV installed capacity (kW) / Pmax (T=Actual or NMOT) How much does a solar power plant cost?
This figure shows the range of unsubsidized LCOE (Levelised Cost of Energy) for PV projects
from 2010 to 2017, taking into account variations in the costs and capacities of individual
projects. The LCOE of fossil fuel plants varies between
0.05 to 0.17 USD / kWh. Between 2010 and 2017, the solar PV global
weighted average LCOE dropped from 0.36 USD per kWh to 0.10 USD per kWh. In certain countries, PV solar power can compete
with conventional fuel plants in However, there are challenges in deploying
solar energy on an even larger scale. Today, the intermittent nature of electricity
generation from solar energy limits its deployment. This means that we need to address the issue
of energy storage. How can we store the energy produced by photovoltaic
systems and enable the deployment of this technology on a grand scale? For an in-depth analysis of this question,
we invite you to take our course on energy storage and hope to see you soon. iPolytek Professional Development Courses
for Engineers

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