## 1 Introduction  
Implementing environmentally friendly systems and using renewable energy are not luxuries anymore. They are needed to sustain the planet's limited resources and maintain the environment. Transportation is one of the main sectors that depletes traditional fuel reserves, in addition to damaging the environment. As per the World Bank Group database and Energy Information Administration (EIA) statistics, overall worldwide energy consumption is continuously increasing. The 2016, the International Energy Outlook predicted that the annual transportation sector energy consumption was increasing at an average rate of 1.4%, from 104 quadrillion British thermal units (Btu) in 2012 to 155 quadrillion Btu in 2040 [1; 2; 3]. As for the transportation sector, the Energy Information Administration (EIA) has released data showing that the transportation of people and goods accounts for approximately 25 percent of global energy consumption [2]. Passenger transportation, in particular, using light-duty vehicles, accounts for most of the transportation energy consumption. Therefore, establishing reputable public transportation systems is necessary, and using clean energy instead of fossil fuels within the nominated system is of extreme importance. Depletion of non-renewable energy sources, such as fossil fuels, is not the only problem associated with using such fuels for transportation. Production of remarkable amounts of dreadful emissions that hurt the environment and inhabitants' health is a problem of equal significance. Twenty percent of global CO\({}_{2}\) emissions are caused by the transportation sector. Streets occupy a large area of public land, which offers a unique opportunity to implement green technology fundamentals and elements that improve communities, the environment, and health. One such technology is using photovoltaics (PV) to generate the required energy to power the electric buses. PV generated energy is sustainable, as it is harvested directly from the sun. As PV technology installation investment costs have decreased, global deployment has rapidly increased. PV systems may be installed near the load, with no need for a fuel source or transmission lines, in essence promoting sustainable local generation. This is very attractive for public transportation, as the energy is consumed locally at the route. The drawback of PV energy is that it is dependent on environmental factors. Power generation depends on solar radiation and temperature. As these are random in nature, and cannot be controlled, the availability of solar generated energy is not as dependable as traditional fuel sources. In addition, PV systems do not generate electricity at night, and generation levels differ by season. To combat this effect, storage systems and grid integration schemes may be employed [4]. In this study, a net-metering scheme is assumed. In essence, this scheme uses a bidirectional energy meter. All energy generated by the PV system that is not consumed by the local load is injected into the grid, and the net consumption is billed at the end of the contract-defined period. Therefore, the PV system may be designed to produce enough energy during the day to cover the complete consumption, storing the night-required energy on the electric grid. The authors in [5] discuss electric buses as a city transportation system with the main target of reducing the carbon footprint. However, the paper does not discuss the bus electrical source. While the authors in [6] focus on the optimization of public transportation electric buses' employment, targeting the minimum capital cost of the fleet, the charging demand and stations, and solving the scheduling problem of engaged electric buses. Hence, it focuses on optimizing the charging systems, with no analysis of the environmental effects of traditional buses and electric buses. In [7], the total cost of ownership (TCO) for different electric buses and diesel buses is studied and outlines some real cases in different cities for using electric buses in public transportation.