Engine:
An electric motor is the basic and the most important part of a solar car. It should work with optimal power and the
efficiency should be high. The power of the motor can be transferred to the
wheel by using chain and strap. The wheel and the strap can be used as plugged as well; by means of this, the mechanical loss can be
reduced and the efficiency of the system increases. Most of the limitations of the classic commutator DC motor are due to the need
of the brushes to be pressed on the commutator. This creates friction. At higher speeds, brushes have increasing difficulty in maintaining contact. Brushes may bounce off
and this causes roughness on the commutator surface, creating sparks. This limits the maximum speed of the machine. The current density per unit area of the brushes limits the output of the motor. The imperfect electric contact also causes electrical noise. Brushes eventually
are worn out and replacement of the brushess are required. The commutator assembly on a large machine is a costly element, requiring precision assembly of many parts.These problems are eliminated in the brushless motor. In this motor, the mechanical "rotating switch" or commutator/brushgear assembly is replaced by an external electronic switch synchronised
with the rotor's position. Brushless motors typically have
an efficiency of 85-90%, whereas DC motors with brushgear
have typically an efficiency of 75-80%.
Electronics:
An electronic network inside the car controls the telemetry, communications,
indicators and driver interface and power systems.
Battery:
Battery is the main power supply of a vehicle. A battery is a device that stores chemical energy and makes it available in an electrical form. To get the appropriate voltage and capacity, a battery group with series/parallel combination can be
arranged. Lead-acid batteries are inexpensive, relatively safe and easily recyclable, but have a low energy-to-weight ratio which is a serious limitation when trying to build lightweight vehicles. Also they have a low charge/discharge output ratio. Because of these reasons, they are not preferred to
be used in solar cars. New battery technologies are continuously
being improved and these improvements can offer better energy-to-weight ratios, lower costs and increased battery life. The nickel-metal-hydride battery is one
of such technologies that has received a great deal of attention as a near future solution. Nickel-metal-hydride batteries offer about twice the energy capacity for the same weight as a current lead-acid battery.
Other
battery types with an even greater energy density
are Lithium ion and Lithium polymer batteries. The widespread use of storage batteries will continue to grow in the future.
In order to obtain a quick and safe charge control for the battery,
it is necessary to use a charge control circuit. The
electrical characteristics of the solar panels varies a lot depending on temperature, light angle and intensity and the electrical load. Maximum power point tracker (or MPPT) is a high efficiency DC to DC converter that operates a photovoltaic (PV) solar panel or array at a voltage at which maximum power is extracted and
it efficiently converts that higher (normally) voltage down
to a lower voltage battery or external electric load. An
MPPT will typically increase power delivered to the system
by 10% to 30%, depending on climate conditions and battery
state of charge. The benefits of MPPT regulators are higher during cold weather, on cloudy or hazy days or when the battery is deeply discharged.
A solar module or panel is an integrated assembly of interconnected solar cells designed to deliver a selected level of working voltage and current at its output terminals and
is applied for incorporation in a solar power system. Here the produced energy is stored in the batteries while power is not being
absorbed; if power is pulling it is added to the power itself. Modules are assembled with sticking on to the outer part of the car attaching importance to aerodynamic configuration and the
zenith angle. The transformation outputs of the solar cells are very sensitive to the outer load. Because of using the MPPT controller which arranges the load to keep the voltage-current values at optimum level guarantees obtaining the highest power from the solar generator.