Solar Photovoltaics (PV), commonly referred to as solar energy, is the technology that converts sunlight into electricity. This process happens through something called the photovoltaic effect – a phenomenon where light, made up of tiny particles called photons, strikes a solar cell and knocks electrons loose, generating a flow of electricity. That’s why solar cells are called “photovoltaic,” or PV for short. These cells are grouped together in larger units called solar panels, which are installed on rooftops, open land, or parking structures to produce usable power.
Solar panels come in a variety of sizes and output capacities, depending on the application. For example, a typical commercial-grade panel might be rated at 600 watts, meaning it can produce 600 watts of electricity under ideal sunlight conditions. However, even under perfect conditions, solar panels don’t convert all the sunlight they receive into electricity. Most panels today are around 22-24% efficient, which means they convert only about a quarter of the incoming sunlight into usable energy. The rest is lost as heat or reflected away. So, while they may appear simple, solar panels are highly engineered systems that maximize energy production from a free and abundant resource: the sun.
Solar array sizes are typically measured in kilowatts (kW) of electrical power, which represents the system’s maximum output under ideal sunlight conditions. To build a system that produces 1 kilowatt, you’d need multiple solar panels working together. For example, if you’re using 500 watt panels, it would take two panels to make up 1 kW of capacity (500 watts × 2 = 1 kW). In commercial solar installations, systems are often sized at 50 kW, 250 kW, or even several megawatts, requiring hundreds or thousands of panels. The total system size helps determine how much energy it can generate over time, ultimately impacting cost savings and return on investment.
1 Kilowatt (kW) = 1,000 watts
1 Megawatt (MW) = 1,000,000 watts (or 1,000 kW [Kilowatts])
1 Gigawatt (GW) = 1,000,000,000 watts (or 1,000,000 kW, or 1,000 MW [Megawatts])
Need a clearer distinction between power (kW) and energy (kWh)? Jump to What’s the Difference Between kW and kWh? for a detailed explanation.
Want to know what specific equipment makes up a PV system? Explore What Equipment Is Used in a Solar PV System, and What Mounting Options Exist? for details on panels, inverters, and more.