Megawatt vs Megawatt-Hour: What’s the Difference, Why It Matters?

If you get confused after seeing megawatt (MW) and megawatt-hour (MWh), this blog is for you.

What is a Megawatt (MW)?

A megawatt (MW) is a unit of power, it’s the rate at which energy is generated or consumed. So, 1 MW equals 1,000,000 watts.

Think of your car’s speedometer — it shows your speed right now and not how far you’ve gone. The same way megawatts tells you how much power is being produced and used at instant. 

You’ll see MW used to describe the capacity of power plants or solar farms. Here is one example for you, if a 1 MW solar array is producing 1 MW of power under perfect sunlight and is running continuously at full power for 24 hours, it will deliver 24 megawatt-hours (MWh).

In short, MW is about potential output or instantaneous power.

What is the Difference Between MW and MWh?

A megawatt-hour (MWh) is a measure of energy.

• MW = Power (capacity at an instant)
• MWh = Energy (power produced over time)

Think of it like water flowing from tap—the speed of the flow is MW, but the amount of water you get in that bucket after an hour is MWh.

Making it more simple for you:

• Running 1 MW system for 1 hour equals 1 MWh of energy
• Run it for 3 hours = 3 MWh
• Run it for a whole day = 24 MWh

To make it simple: MW tells you “how big,” while MWh tells you “how much over time.”

How Do You Convert MW to MWh (and Vice Versa)?

This is the formula:

Energy (MWh) = Power (MW) × Time (hours)

We have an example:

• A 5 MW solar farm running for 3 hours = 15 MWh.
• A 2 MW wind turbine running for 10 hours = 20 MWh.

But the thing is: real-world systems don’t really operate at full capacity all the time. Solar panels don’t really generate power at night and the output is affected by clouds and shade if you talk about the day. This is where you need the capacity factor—it’s the percentage of time a system produces near its maximum output.

In the U.S., a regular solar farm might have a capacity factor of like 20–25%. So a 1 MW solar system won’t deliver 8,760 MWh per year (which would be the math if it ran at 100%); it’ll likely produce closer to 1,700–2,200 MWh annually also depending on location and design.

Common Mistakes People Make with MW, MWh, and MW/h

One of the most common mistakes people make is mixing up MW and MWh. Even news outlets get this wrong.

• MW = capacity (instantaneous power).
• MWh = energy produced or consumed over time.
• MW/h = a different concept altogether. It means “megawatts per hour,” which means a rate of change in power, not energy. It’s rarely used outside technical modeling.

Best practice would be to stick with MW for capacity and MWh for energy. That way, you’ll avoid confusion.

How Many Solar Panels, EV Miles, or Homes Does 1 MW or 1 MWh Represent?

Understanding megawatts (MW) and megawatt-hours (MWh) in everyday terms would help a lot so let’s break them down with real-world examples.

1 MW of Solar Panels

To build a solar system with a capacity of 1 MWp (megawatt peak), you’d need around 2,200 panels and each panel should be about 440 watts in size. That’s roughly the size of a utility-scale solar project rather than a typical rooftop installation.

What 1 MWh Can Power

• A single megawatt-hour (MWh) of energy equals to 1,000 kilowatt-hours (kWh).
• On average, that’s enough electricity to run a U.S. household for like one month because the average home uses like ~900 kWh per month.
• For electric vehicles, 1 MWh could deliver around 3,000–4,000 miles of driving range, depending on the EV’s efficiency.
• In simpler terms, 1 MWh can keep 10,000 LED light bulbs (10 W each) glowing for 10 hours straight.

Regional Differences
These numbers are average, but they can be different depending on the location and technology. Like homes in the U.S. use more electricity than Europe or India. So while 1 MWh might cover a month of power for a U.S. household, it could also stretch even further in regions where average household power usage is lower.

Thinking about energy this way makes the scale of MW and MWh more relatable—and shows just how much impact solar systems can have when scaled up.

How Do MW and MWh Matter for Solar Projects and Proposals?

If you’re in the solar industry—or even considering solar for your business—understanding MW vs MWh is critical.

• MW (Capacity): Defines the size of your system. Installers and engineers use this for grid interconnection, inverter sizing, and system layout.
• MWh (Energy Yield): This is what really matters to customers. It shows how much electricity the system will actually generate over time.

For solar proposals, both numbers need to be presented:

• MWp (peak installed capacity in direct current).
• Expected MWh/year (annual production estimate).

Developers also model different scenarios—like P50 and P90 yield projections—to show the most likely vs conservative energy production. These numbers drive financial models, Power Purchase Agreements (PPAs), and project bankability.

MW tells you the size of the system, MWh tells you the value. Always include both in proposals to avoid confusion and build trust with buyers.

How Can Readers Quickly Check or Convert Units?

Here are some handy tools:

• U.S. Energy Information Administration (EIA) Glossary – authoritative definitions.
• International Energy Agency (IEA) Unit Conversions – easy reference.
• Online Calculators – many sites, including RatedPower, let you plug in MW and hours to instantly get MWh.

A simple cheat sheet is also helpful:

• 1 MW × 1 hour = 1 MWh
  
  
• 1 MWh = 1,000 kWh
  
  
• 1 MW × 24 hours = 24 MWh

In solar, MW and MWh are two sides of the same coin — capacity versus output. A project’s MWp (megawatt-peak) refers to its installed DC capacity, often calculated by multiplying the number of solar panels by their rated wattage. But what owners and financiers truly care about is how much electricity the system will generate over time — expressed in MWh (megawatt-hours) per year.

That bridge between MW and MWh is defined by the capacity factor, local solar irradiance, system design, and performance losses. RatedPower notes that energy yield modeling often relies on P50 and P90 production estimates, which account for uncertainty in weather and system behavior. 

Similarly, NREL and the IEA emphasize that these yield concepts are critical for bankability in PV projects.

For installers and developers, both metrics play distinct roles:

• MW (capacity) is used for system sizing, interconnection agreements, and balance-of-system (BoS) planning.
  
  
• MWh (annual output) is for financial side — from PPA (power purchase agreement) pricing to LCOE (levelized cost of electricity) and revenue forecasts.

When you’re preparing proposals, it’s best practice to present both MWp and expected MWh/year, and clearly state the assumed capacity factor and losses (such as shading and inverter efficiency). This avoids confusion for buyers who may mistake MW for production, and it allows greater transparency.

FAQs

What is the difference between MW and MWh?
A megawatt (MW) measures power capacity, while a megawatt-hour (MWh) measures energy produced or consumed over one hour.

Is MW a measure of energy or power?
MW is a measure of power, representing the rate of energy generation or consumption.

What does MWp mean?
MWp refers to “megawatt-peak,” the maximum DC capacity of a solar PV system under standard test conditions (Medium).

Can you compare MW to kW and MWh to kWh?
Yes. 1 MW equals 1,000 kW, and 1 MWh equals 1,000 kWh.

How many kWh are in 1 MWh?
1 MWh equals 1,000 kilowatt-hours.

How do you calculate energy from power?
Energy (E) is calculated by multiplying power (P) by time (t), expressed as E = P × t 

Conclusion: What Should Installers and Buyers Remember About MW vs MWh?

To wrap things up:

• MW = instantaneous power capacity.
• MWh = energy generated over time.
• Conversion is simple: MWh = MW × hours.
• In solar proposals, always show both capacity (MW) and expected energy yield (MWh).

For solar professionals, getting these numbers right can make or break a proposal. That’s where solar design software comes in. Platforms like ARKA 360 help you design projects, automatically calculate expected MWh from installed MWp, and generate proposals that clearly communicate value to clients.

Sources

• U.S. Energy Information Administration (EIA) – Glossary & Electricity Explained
• International Energy Agency (IEA) – Energy Units & Conversions
• RatedPower – Megawatt vs Megawatt-Hour
• EnergySage – How Many Solar Panels Do I Need?
• Gridcog – MW vs MWh Explained
• NREL – PV System Modeling and Capacity Factors

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