Megawatt
A megawatt (MW) is a unit of power equal to 1,000 kilowatts (kW) or 1 million watts (W). In the solar industry, the megawatt is one of the most important units used to describe the scale of PV systems, the capacity of utility infrastructure, grid interconnection limits, and overall project generation capability.
Solar designers, installers, EPCs, and developers use megawatts to size arrays, evaluate inverter capacity, plan interconnection, and estimate energy production across residential, commercial, and utility-scale applications. A project’s MW rating also determines financial modeling, BOS planning, and engineering requirements.
Megawatts are foundational for solar design workflows built inside platforms like Solar Designing and for energy planning tools such as Solar ROI Calculator.
Key Takeaways
- A megawatt (MW) is equal to 1 million watts, used to measure the size and power capacity of solar systems.
- MW is used to distinguish DC array capacity and AC inverter output.
- Large-scale commercial and utility solar projects are measured in megawatts.
- Knowing MW values is critical for layout design, energy modeling, financial forecasting, and grid interconnection.
- Software platforms like SurgePV help accurately plan, model, and optimize MW-scale systems.
What Is a Megawatt?
A megawatt is a measure of power—specifically, the rate at which energy is produced or consumed. In solar, it is used to represent:
- The DC capacity of a solar array
- The AC output capacity of an inverter system
- The grid export limit of an interconnection
- The total size of utility-scale solar farms
- The demand or load of large industrial facilities
For example:
- A typical home uses 1–5 kW
- A commercial building may install 100–500 kW
- Utility-scale solar farms range from 5 MW to 500+ MW
Related terms include Kilowatt (kW), Gigawatt (GW), and PV System.
How a Megawatt Works in Solar
Megawatts are used to define both DC and AC sides of a solar project:
1. DC Megawatt (MWdc)
Represents the combined nameplate power of all solar modules.
Used for:
- Layout design
- Module selection
- Performance modeling
- BOS sizing
2. AC Megawatt (MWac)
Represents the usable grid output after inverter conversion.
Used for:
- Interconnection approvals
- Export limits
- Utility reporting
- Capacity planning
The ratio between MWdc and MWac is known as the DC/AC ratio, commonly between 1.1 and 1.3 depending on design and climate.
See Inverter Sizing for how MWac is configured.
Types / Variants of Megawatt Ratings in Solar
1. Installed Capacity (MWdc)
Total module nameplate capacity.
2. Inverter Capacity (MWac)
Maximum AC power delivered to the grid.
3. Net Capacity
Actual output after system losses.
4. Capacity Factor
Percentage of actual output vs. theoretical maximum.
5. Peak Megawatt Output
Maximum real-time generation under strong sunlight.
How Megawatts Are Measured
Power (MW) Formula
Power (MW) = Energy (MWh) ÷ Time (Hours)
Energy Production
A 1 MW solar system typically generates:
- 1,300–1,800 MWh per year depending on location
- Higher in high-irradiance areas like the U.S. Southwest, India, Africa, Middle East
Module Count
Number of modules per MW:
- 1 MW ≈ 2,200–2,600 modules (assuming 380–450W modules)
Area Requirements
Typical land usage:
- Rooftop: 5,000–8,000 sq ft per 100 kW
- Ground-mount: 4–6 acres per MW
Practical Guidance for Solar Designers & Installers
1. Understand both MWdc and MWac
These determine panel count, inverter selection, and interconnection.
2. Use accurate MW sizing for utility applications
Grid operators require precise MWac data for:
- Voltage regulation
- Frequency stability
- Export management
See Grid Interconnection.
3. Check inverter loading ratios
A DC/AC ratio between 1.15–1.30 often maximizes value without excessive clipping.
4. Use software to validate energy yield
Use modeling tools in Solar Designing to simulate kWh production per MW installed.
5. Plan BOS & O&M based on MW scale
Larger MW projects require:
- Wider service pathways
- Accessible inverters
- Ground coverage planning
- Terrain grading
6. Use MW values in financial modeling
When estimating returns, use the Solar ROI Calculator to forecast payback based on MW size.
Real-World Examples
1. Residential Rooftop System
A homeowner installs a 10 kW (0.01 MW) solar array that produces ~14 MWh per year.
2. Commercial Building
A logistics center installs a 750 kW (0.75 MW) rooftop system offsetting 20–40% of its energy consumption.
3. Utility-Scale Solar Farm
A developer builds a 100 MWac solar farm generating approximately 170,000 MWh annually—powering 25,000+ homes.
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