Renewable Energy Sources Basics: How Solar Energy is Converted to Electricity?


Renewable Energy Basics: How solar Energy is Converted to Electricity?
Renewable Energy Basics: How solar Energy is Converted to Electricity?

How is solar energy converted to electricity?

Renewable energy has an increase in demand as more companies and consumers join the combat against climate change. And among the renewable energy sources, solar energy seems to have a bright future in the Philippines.

But how does the energy from the sun convert into electricity?

Extensive technical planning is needed when building a solar power plant. However, the conversion process of electricity from the sun is easy to understand. Here, we will discuss the simple steps of how the energy from the sun powers millions of homes in the Philippines.

Almost all solar power plants have three major pieces of equipment. The solar arrays, the inverter stations, and the transformers. The rest of the auxiliary equipment supports these main components to generate electricity from the sun. 

Now let us briefly define the functions of the three major components:

Solar arrays

The Solar Arrays - absorbs the light energy and induces a direct current (DC) flow, or DC electricity. A solar array is a group of solar panels connected to generate a large power output for transmission and distribution to consumers. 

Solar power plant inverter station

The Inverter Stations - converts DC to AC electricity. The output from the solar panel is DC electricity, but our homes require AC or alternating current. At the same time, the solar power plant also supplies electricity to its auxiliary equipment or house load that runs in AC.

Solar power plant transformer stations
The Transformers - steps up the output AC voltage from the inverter station for station use and transmission. One of the solar power plants in the Philippines has two voltage-rating transformers. One steps up the output voltage of the inverter station to 13,800 volts, and the other steps up that voltage even higher to 69,000 volts for transmission to the grid. Other solar power plants with a higher installed capacity and at a remote location may even have a higher transmission voltage.

Now, back to the question - How does the energy from the sun convert into electricity?

We have actually answered this question after defining the three major components of a solar power plant.

Solar Power Plant Operational Process:

  1. The light energy from the sun is absorbed by the connected solar panels or solar arrays. The solar panels then generate DC electricity that flows into the inverter station. Also, the orientation of these solar arrays is designed to absorb the most amount of sunlight during its operation. 
  2. The DC electricity from the solar panels is inverted at the Inverter Station so that AC electricity will flow to the transformers. 
  3. Lastly, the output AC voltage of the Inverter Station is stepped-up for station use and transmission. The voltage rating of the transformers depends on the design of the power plant. But for this example, the voltage rating for station use is 13,800 volts, and the transmission is 69,000 volts. Pure renewable energy from the sun only has three easy steps to give you clean electricity.

So what are the advantages of Solar among other renewable energy sources?
  1. The energy source is the sun - we have an unlimited energy source of electricity as long as the sun rises. “The amount of sunlight that strikes the earth's surface in an hour and a half is enough to handle the entire world's energy consumption for a full year”. The Philippines is a tropical country with enough daylight to power our homes throughout the year.
  2. It is clean and quiet - a 22-MW solar power plant displaces 17,000 metric tons of CO2 yearly. This displaced carbon equals 3,783 gasoline-powered vehicle emissions for a cleaner environment. And, solar power plant operation is relatively quiet. It can generate at maximum capacity without disturbing the peace of a nearby community.
  3. A solar power plant has no moving parts - engineers hate equipment or facilities with moving parts. Multiple moving components only mean considerable sources of failures and are costly to maintain. An expensive routine maintenance cost is not a burden for solar power plants in the Philippines. Solar panels are in a fixed position without a rotating component. The advantage it brings to consumers is availability because it has a low chance of power outage due to equipment failure. The low maintenance cost can also translate to a cheaper price per kilowatt hour.
How about disadvantages? Solar energy is all good, but it has three main disadvantages from my point of view.
  1. Solar energy is not a base-load power plant - a base-load power plant delivers stable electricity 24 hours a day. For obvious reasons, solar power plants can not run for 24 hours. Though other facilities store excess power in batteries, the operation is not a base load since the full-load capacity is only available during the daytime.
  2. Solar power plant inefficiency during cloudy and rainy days - the efficiency of the power plant can immediately decline by as much as 30% when a thick cloud hovers over the solar panels, how much more when it rains. The Philippines will have its typhoon season from June to November with a lower solar power generation. As solar power generation reduces, other conventional forms of energy will compensate to meet the demands of the consumers.
  3. Some solar energy is expensive - we now need to understand two acronyms, WESM and FIT. Did you know that there is a spot market for electricity? And that is called the Wholesale Electricity Spot Market (WESM). WESM is a government-run department that facilitates selling electricity from the Power Plants. Electricity prices in WESM are negotiated based on supply and demand. Then we have the FIT or the Feed-In-Tariff. FIT is an agreement between the government and the power plant investors. FIT pesos per kilowatt-hour are guaranteed prices for electricity sold by eligible power plants. The government opened this contract to encourage investors to finance power plants in the Philippines and increase the supply over the demand. The average price per kilowatt hour daily at WESM (2023 data) runs between 5 to 6 pesos, lower than the 8 to 9 pesos per kilowatt-hour for FIT-eligible solar power plants.
  4. Solar energy displaces vast farmlands - a 35-hectare solar power plant produces 22 MW of electricity - while a 23-hectare coal-fired power plant generates 246 MW of electricity. This land area per MW comparison shows one apparent disadvantage of a solar power plant. Most, if not all, solar power plants were once sugar cane, rice, and corn farms. And it is my general opinion - that by increasing our solar power generation, we have unintentionally slightly reduced food production.
Those are some of the advantages and disadvantages of a solar power plant. Though the future looks bright with solar, we can also see multiple disadvantages.
Solar energy is significantly contributing to the energy needs of the Philippines

Across the country, solar power plants continue to expand - as a source of clean and renewable energy. But, what is the total installed capacity of solar power plants in the Philippines?
  1. Luzon - has the largest installed capacity of 978.2 MW and can power 978,000 homes daily.
  2. Visayas - has 487.4 MW of installed capacity, equivalent to 487,400 per day.
  3. Mindanao - has 83.7 MW of installed capacity, equivalent to 83,700 homes per day. Mindanao shows an attractive potential for future installation.
We have completed our discussion on how solar energy is converted to electricity. We mentioned the simple details of how electricity is generated from the sun and - touched on details of the advantages and disadvantages. In conclusion, I still think that solar energy has a huge potential to secure the power requirements of the Philippines. Especially in Mindanao, the government can still find ways to encourage more investors to build solar power plants since it has the least amount of installed capacity. The government also has to carefully strategize in approving the construction of solar power plants because it may have an indirect impact on the country’s food security. Though we are displacing metric tons of CO2 from the environment, we may also be displacing metric tons of grains and sugar. I do hope soon that the advancement of technology can finally overturn the disadvantages, thus declaring solar the most reliable source of clean and renewable energy in the Philippines.