How Your Electricity Is Bought: Understanding PSAs, IPPs, and the WESM

Where Does Your Electricity Come From?
Understanding Power Supply Agreements, IPP Contracts, and the Wholesale Electricity Spot Market

When you flip a light switch, you probably don't think about where the electricity comes from. Most people simply expect power to be available 24 hours a day.

Behind that simple switch, however, is a complex network of power plants, transmission lines, contracts, and electricity markets working together to keep the lights on.

In the Philippines, three important concepts determine how your electricity reaches your home:

• Long-term Power Supply Agreements (PSAs)
• Independent Power Producer (IPP) Contracts
• The Wholesale Electricity Spot Market (WESM)

Let's look at each one in simple terms.

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1. Long-term Power Supply Agreements (PSAs)

Imagine your condominium signs a five-year contract with a water delivery company to supply water every day at an agreed price.

Power utilities do something very similar.

A Power Supply Agreement (PSA) is a long-term contract between an electricity distributor (such as Meralco) and a power generation company.

The contract typically specifies:

• how much electricity will be supplied
• the agreed pricing formula
• how long the contract will last
• the responsibilities of both parties

Many PSAs last anywhere from 10 to 20 years.

Why are PSAs important?

Electricity cannot simply be "ordered" at the last minute.

Power plants require billions of pesos to build and maintain. Investors are only willing to finance these facilities if they know someone will buy the electricity they produce.

Long-term contracts provide:

• Stable electricity supply
• More predictable pricing
• Better planning for utilities
• Greater confidence for investors building new power plants

Without these agreements, utilities would have to buy electricity every day on the open market, where prices can fluctuate dramatically.

Think of it this way...

Instead of buying rice every single day at whatever the market price happens to be, imagine agreeing today to buy rice from a farmer for the next ten years at an agreed pricing formula.

Both the buyer and seller benefit from greater certainty.

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2. Independent Power Producer (IPP) Contracts

Years ago, the Philippine government faced severe electricity shortages.

To encourage private investment, the government invited companies to build power plants instead of relying solely on government-owned facilities.

These private companies became known as Independent Power Producers (IPPs).

Rather than selling electricity directly to consumers, many IPPs signed long-term contracts with government-owned utilities or distribution companies.

These contracts often guaranteed that the power plant would recover its investment costs, allowing companies to build expensive generating facilities with less financial risk.

Why were IPP contracts created?

During the 1990s, the Philippines experienced frequent rotating brownouts because there wasn't enough generating capacity.

The government needed new power plants quickly.

IPP contracts encouraged private companies to invest billions of pesos into new generating facilities.

Without those investments, power shortages could have lasted much longer.

Are IPP contracts still important today?

Yes.

Many of the country's existing power plants were built under IPP arrangements.

Although newer power projects are often developed under different market structures, IPP contracts played a major role in expanding the country's electricity supply.

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3. The Wholesale Electricity Spot Market (WESM)

Not all electricity is purchased through long-term contracts.

Sometimes demand suddenly increases.

Sometimes a power plant unexpectedly shuts down.

Sometimes renewable energy like solar or wind produces more—or less—electricity than expected.

That's where the Wholesale Electricity Spot Market (WESM) comes in.

Think of WESM as the country's "electricity marketplace."

Power generators offer electricity for sale.

Distribution utilities and other qualified buyers purchase electricity based on current supply and demand.

Unlike long-term contracts, prices in WESM change every hour—and sometimes every few minutes—depending on market conditions.

An everyday analogy

Imagine buying airline tickets.

If you purchase months in advance, you often get a stable price.

If you buy on the day of the flight, prices can be much higher—or occasionally lower—depending on demand.

WESM works in a similar way.

Electricity bought at the last minute is priced according to real-time market conditions.

Why do prices change?

Several factors affect WESM prices, including:

• High electricity demand during very hot weather
• Unexpected outages at power plants
• Maintenance shutdowns
• Fuel prices
• Availability of renewable energy such as solar and wind

When electricity supply becomes tight, prices usually increase.

When plenty of generating capacity is available, prices generally fall.

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How Do These Three Work Together?

The Philippine power system doesn't rely on just one method of buying electricity.

Instead, it combines all three.

• Power Supply Agreements (PSAs) provide stable, long-term electricity for most customer needs.
  
  
• IPP contracts helped build many of the power plants that still generate electricity today.
  
  
• WESM fills the gap by supplying electricity whenever additional power is needed or when market conditions change.

Together, they help balance three important goals:

• Reliability — ensuring enough electricity is available.
• Affordability — keeping costs as stable as possible.
• Flexibility — responding quickly when demand or supply changes unexpectedly.

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Why Should Condominium Residents Care?

Even though residents don't buy electricity directly from power plants, these systems influence the cost of electricity reflected in monthly bills.

For example:

• If long-term contracts provide reasonably priced electricity, bills tend to be more stable.
• If utilities need to buy more electricity from WESM during periods of high prices, electricity costs can increase.
• Building new power plants through long-term investments helps reduce the risk of future shortages.

Understanding these concepts makes it easier to appreciate why electricity prices sometimes change—and why maintaining a reliable power system requires both long-term planning and the flexibility to respond to real-time conditions.

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In Summary

Think of the Philippine electricity supply as a household budget.

• Power Supply Agreements (PSAs) are like signing a long-term contract for essential groceries at predictable prices.
  
  
• Independent Power Producer (IPP) contracts are like hiring builders to construct the supermarket itself so there's enough food for everyone.
  
  
• The Wholesale Electricity Spot Market (WESM) is like buying extra groceries at today's market price whenever unexpected needs arise.

All three play different but complementary roles in ensuring that, when you flip the switch, electricity is there when you need it.