A rooftop solar power system, or rooftop PV system, is a photovoltaic (PV) system that has its electricity-generating solar panels mounted on the rooftop of a residential or commercial building or structure. The various components of such a system include photovoltaic modules, mounting systems, cables, solar inverters…

An energy transition (or energy system transformation) is a major structural change to energy supply and consumption in an energy system. Currently, a transition to sustainable energy is underway to limit climate change.

Renewable energy (also called green energy) is energy made from renewable natural resources that are replenished on a human timescale. The most widely used renewable energy types are solar energy, wind power, bioenergy/biomass, and hydropower.

NRG Energy, Inc. is an American energy company, headquartered in Houston, Texas.

Geothermal energy is thermal energy extracted from the Earth's crust. It combines energy from the planet's formation and from radioactive decay.

Constellation Energy Corporation is an American energy company headquartered in Baltimore, Maryland. The company provides electric power, natural gas, and energy management services.

Open energy-system models are energy-system models that are open source. These models can also be known as open energy models or open-source energy-system models or some combination thereof.

Octopus Energy Group Limited (formerly Octopus Energy Limited and Octopus Energy Holdings Limited), known as Octopus Energy, is a British company operating in the fields of energy generation and supply. It was founded in 2015 with the backing of Octopus Group, a British asset management company.

O.Y. Nofar Energy Ltd., commonly known as Nofar Energy (Hebrew: ע.י. נופר אנרג'י בע"מ), is an Israeli renewable energy company headquartered in Kfar Saba.

Energy in Kazakhstan describes energy and electricity production, consumption and import in Kazakhstan and the politics of Kazakhstan related to energy. Kazakhstan, which has oil, gas, coal and uranium reserves, is a net energy exporter and a leading energy producer in the Commonwealth of Independent States (CIS).