User guidance

The Setting section presents the capacity of solar PV panels that can be accommodated on a single (or multiple) rooftop(s) as well as the self-consumption of a single (or multiple) building(s).

The section is tied to a toolset (sliders, drawing tools on the map and a Set Input tab) that allows users to resize the system, amend the self-consumption ratio, and tune the fiscal and financial parameters as needed for individual cases.

The Set Input tab allows users to adjust some of the parameters of the analysis. This window comprises two sets of parameters: non-alterable and alterable.

The non-alterable parameters – such as the PV capacity, surface area, number of buildings and annual consumption – are precalculated by the SolarCity simulator based on the user’s chosen configuration and area of interest. The annual consumption figure responds to user interaction via the consumption subsection of the tuner. 

Alterable parameters, such as storage capacity, PV efficiency, system cost, interest rate, loan, loan period, emission factors, average consumption, tariffs, tax credits and subsidies can be adjusted as required. The SolarCity simulator recalculates the outputs of the ‘Financing’ and ‘Environmental (and Social) Benefits’ sections of the ‘Output’ panel.

For instance, by inputting values for subsidies or income tax credits, the SolarCity simulator can assess the economic feasibility of rooftop solar PV systems. This assessment is based on a simplified model that assumes a solar programme aiming at full utilisation of all suitable rooftop spaces.

Note that the output metrics comprise the direct accounting cost of the subsidy or income tax credits to the municipal or central authorities and the prospective value created by these interventions. This first approximation does not estimate the indirect costs of implementing the schemes or measure the positive and negative externalities that may arise from their implementation. 

All outputs from the SolarCity model can be downloaded by clicking on the ‘Get report’ icon in the ‘Results’ section.

 

SolarCity Glossary


(Total) annual consumption

The amount of electricity used by selected household(s) per year.

Average annual consumption

The amount of electricity used on average per household per year.

Benchmark price

Price to be paid to a consumer per kWh of electricity fed into the grid (on-grid) or saved in the storage system (off-grid) if there is any surplus power generated from the rooftop solar PV system. The default values are obtained from the local authorities in the city but can be edited by users.

CO2 emission per kWh (kg)

An estimation of the carbon dioxide emissions per kWh of electricity generated from combustion systems, considering the carbon footprint of solar photovoltaic panels.

CO2e emissions per kWh (kg)

An estimation of the equivalent carbon dioxide emissions in other forms (greenhouse gasses) per kWh of electricity generated from combustion systems considering the carbon footprint of solar photovoltaic panels.

CO2 emissions per passenger car per year (kg)

Parameter used to estimate the equivalent carbon savings achieved by a PV installation in terms of passenger vehicles taken off the road. The default value for a passenger vehicle is set to 4,600 kg, assuming an average gasoline vehicle has a fuel economy of 9.35 kilometres per litre and drives 18,500 km per year (EPA, 2019). This is used in SolarCity as a basic indicator only.

CO2 sequestrated per tree per year (kg)

Parameter used to estimate the equivalent carbon savings of an installation in terms of number of mature trees planted in a tropical environment. The default value is set to 22.68 kg, assuming an average tropical tree (Egbuche Christian, 2018).

Down payment

The initial investment, starting capital or advance payment percentage of the total investment before other payments, deductions or returns .

Electricity price

Price to be paid by a consumer per kWh of electricity consumed from the utility. The default values are obtained from the local authorities in the city, but can be edited by users.

Generation subsidies (central government, provincial, municipal)

Direct accounting costs from central government or from provincial or municipal authorities of implementing an incentive such as a generation subsidy. The default values are obtained from the local authorities in the city, but can be edited by users.

Income tax (corporate)

Tax payable by cooperatives, limited liability companies and trusts in the city. The default values are obtained from the local authorities in the city.

Income tax credit

The percentage of the tax payable that can be waived from the liability. This can be edited by users.

Installation subsidy

The subsidy that is given to building owners to reduce the initial investment required to install the rooftop solar PV system. The default value is zero but can be edited by users.

Loan

The sum of money that is borrowed and is expected to be paid back with interest over a specific period.

Loan period 

The period over which the loan is to be repaid.

NOx emissions per kWh (kg)

An estimation of the nitrogen oxides emissions per kWh of electricity generated from combustion systems. 

Number of buildings

The number of buildings being actively assessed; a promoter can assess multiple buildings simultaneously.

Operation and maintenance

All costs that are related to daily operation, including the replacement of minor components.

Panel lifespan

Most solar panels come with a warranty of 20–25 years (covering their ‘useful’ lifetime). Over the expected lifetime, most panels continue to operate at low efficiency. In most cases, solar panels lose about 1% of their efficiency over each year of operation.

PM 2.5 emissions per kWh (kg)

An estimation of the particulate matter emissions with a diameter of less than 2.5 micrometres per kWh of electricity generated from combustion systems. 

PV capacity 

Total peak electrical capacity of solar PV panels installed.

PV investment

Cost of the solar PV system, including shipment, taxes and installation. This is obtained from local authorities in the city.

PV efficiency

The ratio of useful electrical energy produced to the amount of solar energy incident on the cell under standardised testing conditions.

Rental cost

Under the lease model, a private or public investor will pay an annual rent to the building owner(s) and benefit from the returns derived from the solar PV system.

Salvage cost

Salvage cost is the estimated residual value of a rooftop solar PV system at the end of its useful lifetime.

Self-consumption

Self-consumption is defined as the ratio of the energy use from on-site generation to the total energy generated.

Storage capacity 

The total amount of energy that a solar battery can store. This can be edited by users.

Storage investment

Cost of the storage system, including shipment, taxes and installation. This is obtained from local authorities in the city.

Surface area (m2)

Area of the rooftop surface covered with solar PV panels.