# Exploring the Feasibility of Autonomous Lighting Systems for Pedestrian Crossings in Off-Grid Areas
## 2 Materials and Methods
### Description of the Autonomous Lighting System  
Figure 14 shows a schematic diagram of the power supply system for the autonomous lighting system. The installation consists of eight photovoltaic panels, labelled PV1 to PV8, and two MPPT battery charge controllers. The proposed components of the PV system are presented in a configuration that can be mounted on light poles. The key components of the system are the four batteries, labelled B1 to B4, installed to store the electric energy produced in the PV panels and to supply power to the LED luminaires and control electronics.  
An outdoor battery installation has an influence on low-temperature operation and deep discharges, leading to irreversible damage. Therefore, the manufacturing technology of the batteries must be chosen appropriately such that the operating conditions do not damage energy banks before the end of the lifespan declared by manufacturer.  
The operating conditions of the installation require a special control algorithm to meet the lighting requirements and to store a sufficient amount of electric energy during periods of reduced solar radiation. These two requirements are quite difficult to meet, so the aim of this article is to indicate the possibilities of fulfilling these requirements.  
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multicolumn{5}{c}{**Number of the Scenario**} \\ \cline{2-6}  & **1** & **2** & **3** & **4** & **5** \\ \hline Pedestrian crossing lighting class & PC4 & PC5 & PC4 & PC4 & PC5 \\ \hline Roadway lighting class & C3 & C3 & C3 & - & - \\ \hline Sidewalk lighting class & P3 & P3 & P1 & P1 & P3 \\ \hline Total active power of all luminaires [W] & 483.6 & 459.8 & 191.6 & 83.6 & 47.7 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Overview of lighting scenarios.  
Figure 13: Lighting scenario 5.  
According to the exploitation experience of autonomous lighting systems, maintaining their efficiency during the winter period can be problematic. The main problem is discharged batteries, and with the comparison to the low availability of PV energy, it makes it impossible to supply power to the LED luminaires. Consequently, such systems do not provide adequate time or an adequate level of illumination, and therefore, safety for pedestrians crossing in the permitted area is limited. This situation can cause road accidents.  
An important element of the system is the pedestrian presence sensor in the waiting area, which detects a person planning to cross the street. The sensor signal is transmitted to the control system, which increases the luminous flux generated by the LED luminaire from a minimum level to a level that ensures the illumination of the crossing according to the required standards. This solution makes it possible to meet two criteria: minimizing energy consumption when there is no pedestrian at the crossing, and illuminating the crossing in the required moment when a pedestrian appears. The final element of the system is a microprocessor controller, which allows for the realization a control algorithm to ensure the correct operation of the entire system. An extra component of the controller is a WiFi modem, which makes it possible to control the parameters of the entire lighting system. That issue is important from an operational and system maintenance point of view.