GLOSSARY
Results section
Definitions:
Access Tiers (Scale 1-5)
Categories that define the electricity services available to household level consumers in a location. The term was established by the World Bank’s Energy Sector Management Assistance Programme (ESMAP) and later adopted as a metric by the Sustainable Energy for All initiative (SEforAll). See the Multi-Tier Access Framework.
Average annual consumption (kWh)
Electricity used on average per household per year.
(Total) Annual consumption (kWh)
Amount of electricity used per household per year.
Annual production (kWh)
Estimated electricity generated by the rooftop solar PV installation in one calendar year.
Buy model
Financing model where the building or estate owner/promoter intends to buy the system. Another model is the ’Lease model’.
Capacity (kWp)
Total peak electrical capacity of solar PV panels installed.
Cars not driven
Equivalent number of passenger cars taken off the streets for one year when electricity is generated by rooftop solar PV installation. A typical passenger vehicle emits about 4.6 metric tonnes (4,600 kg) of carbon dioxide per year (EPA, 2019). It has been used in SolarCity as an indicator only.
Equity Internal rate of return
Discounted 20-year cash flow to equity rate or the annualised effective compounded equity return rate. It is an indicator of the efficiency, quality, or yield of the equity investment and can be used to compare alternative investments.
Greenhouse gases (GHG) avoided (kg)
An estimate of greenhouse gases (CO2: carbon dioxide; CO2e: carbon dioxide equivalent) emissions avoided per year when sourcing electricity from the rooftop solar PV system.
CO2e is a metric measure used to compare the emissions from various greenhouse gases (CO2: carbon dioxide, CH4: methane, N2O: Nitrous oxide, HFCs: Hydrofluorocarbons, PFCs: Perfluorocarbons, and SF6: Sulphur hexafluoride) based on their 100-year global-warming potential.
Investment
Cost of the solar PV system. Estimates include shipment, taxes, and installation.
Lease model
Financing model where the private or public investor buys the solar PV system for a community and homeowners do not bear the cost of investing in the solar PV system. The investor will pay the annual rent to the homeowners, and gain the profit from selling part of the electricity to the consumers for their self-consumption, subsidies, and the remaining electricity to the grid at a benchmark tariff.
Payback (years)
Length of time required to recoup the equity investment that was used to set up the rooftop solar PV system.
Pollutant avoided (kg)
An estimate of specific air pollutants (NOx: nitrogen oxides, PM2.5: Particulate Matter with a diameter less than 2.5 micrometers) emissions avoided per year when sourcing electricity from the rooftop solar PV system. These air pollutants are of great concern to human health.
PV Surface (m2)
Area of the rooftop surface covered with solar PV panels.
Revenue of electricity consumption
Revenue from the electricity consumption savings supplied by the rooftop solar PV system compared to the grid.
Revenue of electricity sold to the grid
Revenue from selling the remaining electricity after self-consumption back to the grid.
Revenue of generation and installation subsidies
Revenue from the subsidy scheme offered to the people for installing rooftop PV systems. It includes the generation subsidy and the installation subsidy.
Self-consumption (%)
The self-consumption is defined as the ratio of the energy use from on-site generation to the total energy generated.
Total revenue
The total aggregated amount of cash flows generated from the rooftop solar PV system during its 20-year lifetime. It is composed of savings from electricity consumption, the revenue of electricity sold to the grid, and the revenue from generation and installation subsidies, minus the operation, maintenance, and rental costs.
Upfront Investment
The initial investment, beginning capital or advance payment before other payments, deductions, or return of profit.
Tropical trees planted
An estimate of the number of tropical trees planted that can capture the equivalent amount of carbon dioxide reduced per year when sourcing electricity from a rooftop solar PV system. It is based on the assumption that an average tropical tree sequesters 22.67 kg of carbon dioxide from the atmosphere every year. It is used in SolarCity as an indicative value.
