Design and Implementation of A 5KVA Solar Power System (A Complete school project Guide)

In a developing country like Nigeria, where there is an alarming dependence on fossil fuels, solar energy remains the most efficient and attractive electricity generation method than other renewable energy sources because of its availability in this region.

Solar Energy is simply defined as energy generated by the sun.

Solar power system is a setup that generates electricity by utilizing the solar energy.

AIMS AND OBJECTIVES OF THE PROJECT:

To carry out precise mathematical analysis and study the working principle of a 5KVA solar power inverter system that converts DC power to AC power. i.e Inverter using 4 deep cycle battery as backup supply for various appliances used in the building.

To provide a source of electrical power with low maintenance cost and zero fuel cost as well as to solve the epilithic and unreliable public power supply in Nigeria.

METHODOLOGY

MATERIALS USED :

Solar Panel (Monocrystalline 545W)

Charge Controller (80A)

Tubular Batteries (12V, 220AH)

Inverter (24V, 5KVA)

Cable (10mm, single core Copper cable)

Knife Change over switch (200amps)

Trunking pipe (16mm)

Binding wire

Solar stand (Galvanised iron)

Circuit Breaker (100amps)

Cable Lug (16mm)

EQUIPMENTS/APPARATUS USED

Multimeter

Plier

Cutter

Hammer

Hack saw

Hand digger

Chisel

Shovel

Insulating tape

Cable tie

INSTALLATION OF THE SOLAR PANEL

Solar Panels are used to convert light from the sun, into Dc electricity to power electrical loads.

Before the installation of the solar panels, the physical inspection and electrical testing of the panels was carried out. Which includes measuring the optimum operating voltage and current using the multimeter while they were exposed to sunlight.

Physical Inspection and electrical testing of the panels

We used six monocrystalline panels rated 545watts, 40.63 volts, 10.17amps.

This type of solar panel was chosen for the job because they are the most efficient solar panels in terms of electricity generation.

These panels perform better in unfavourable conditions such as low light conditions and high temperature.

The solar panels were connected in parallel i.e, all the positive terminals were looped together as well as the negative terminals to bring out a single positive and negative terminal respectively.

The aim was to retain the 40.63volts and to get an optimum total current of 61.02amps which was fed to the 80A charge controller through 10mm copper cable with the 100A circuit breaker serving as a surge protection to the charge controller against overcurrent from the solar panels.

The direct current produced by the solar panels were fed into the charge controller to regulate the voltage and current to the desired value to charge the batteries.

The solar panels were mounted on a galvanized iron solar stand at a tilt angle of 15 deg facing the true south in order to ensure maximum solar energy absorption and proper orientation.

The true south was determined using a compass and the tilt angle was realized after determining the height and width of the solar stand.

FIG 1.0

From FIG.1.0 above, the value of the tilt angle was obtained using the Equation

below

TanѲ = Opp/Adj

The height of the solar stand were given as 14ft, 13ft and 12ft respectively

forming a steep slant.

The width was given as 7.5m

Given 14ft as the maximum height and taking 12ft as the lowest point.

Therefore 14ft – 12ft = 2ft

This implies that;

Tan Ѳ/7.5 = 2 = 0.2667

Tan-1 (0.2667) =14.93 ~ 15 deg

LOOPING OF THE POSITIVE AND NEGATIVE TERMINALS RESPECTIVELY/ ERECTING THE GALVANIZED IRON SOLAR STAND.

INSTALLED SOLAR PANELS.

INSTALLATION OF THE CHARGE CONTROLLER

Charge controller is a voltage and current regulator, installed for optimum and efficient performance of the battery, and to protect the battery from over-charging and undercharging.

The charge controller selected for the job was the Mppt (maximum power point tracking) charge controller because it provides an increase in charging efficiency up to 30% compared to PWM(pulse width modulation) charge controller.

The total currents from the 6 panels was determined by summing up the optimum currents for each panel using the equation below;

Itotal = I1 + I2 + I3 + I4 + I5 + I6

Itotal = 10.17+ 10.17 + 10.17 + 10.17 + 10.17 + 10.17

Itotal = 61.02A

Since the charge controller to be used must be of higher current than that from the solar panels so as to maximize its capacity, the 80A charge controller was chosen for the job.

The charge controller was mounted on a wooden board and securely screwed to the board. It was installed in an area free from rain, properly ventilated and easily accessible.

The output of the solar panel was connected to the PV terminal of the charge controller as indicated. Also the terminal for battery on the charge controller was connected to the batteries.

During the connection, the wire from the solar panel to the charge controller were insulated from each other to avoid short circuit as well as that of the batteries.

PROPERLY INSTALLED CHARGE CONTROLLER AND CIRCUIT BREAKER

INSTALLATION OF THE BATTERIES

A battery is a device that stores chemical energy and converts it to electrical energy. They are used to store the energy produced by the Solar Panel.

We made use of four deep cycle 12V, 220AH tall tubular lead-acid batteries. This was because deep cycle batteries possess 50% DOD (depth of discharge) i.e the percentage of the battery capacity that can be safely drained without damaging the battery.

The batteries were carefully mounted on the battery rack to give room for better cable management and to prevent tripping harzards and potential dangers.

The batteries were connected in series-parallel using the 10mm cables i.e each of the 2 pairs in series and then paralleled.

This arrangement was due to the fact that our inverter system was the 24V system. The batteries used had the hydrometer used to check the specific gravity of the battery’s electrolyte.

Using the cable lug, the battery cables were firmly tightened to each terminal of the battery to avoid ionization.

INSTALLED BATTERIES

INSTALLATION OF THE INVERTER.

An inverter is a device that converts direct current (DC) electricity from the solar panels to alternating current (AC) electricity to power household appliances.

The type of inverter employed for the job was the 5KVA Pure sine wave inverter operating at 24VDC.

This type of inverter was selected for the job because it is capable of producing cleaner, smoother, quieter and more reliable electricity to operate appliances and electronics without interference compared to the other types of inverter.

The inverter was mounted in a properly ventilated and easily accessible location. We connected the 24V output terminals from the battery bank to the positive and negative terminals on the inverter.

Then the Live and Neutral output terminals from the inverter was fed to the input terminal of the knife changeover switch to separate the electric utility provider from the inverter and then sent to the distribution board. (These connections were carried using the 10mm single core copper cables and the trunking pipe was used to maintain aesthetics)

FULLY INSTALLED 5KVA INVERTER SYSTEM ON LOAD

INSTALLATION RESULTS /TABLES AND GRAPHS

When the system was used to power the Load in the building, it produced a stable power supply of 240V as measured by the multimeter similar to that of the utility provider at a frequency of 50Hz. Thus, the objective of the project was realized.

Test carried out over 3 days showed maximum voltage and current between 12noon and 5pm as shown on the tables and graphs below.

From the three days reading that was done to observe the weather condition and the system operating function, we picked day 3 as the only day among the three days of the reading as it appeared that the weather was a little bit clearer than the other days.

The battery arrangement which is 24V, 440AH system has a back-up time of 3hours for the building load of 4000W as shown below;

Back-up time = battery watt-hour / Load

= Battery voltage x AH / Load

= 24 x 440 / 4000

= 10560 / 4000

= 2.64 hours ~ 3 hours.

The back-up time can be significantly increased by load shedding and load control.

It was found that at a clear weather condition the solar panels absorbed more light from the sun to enhance the flow of charge on the solar to increase the voltage, resulting to fast charge of the battery. While on cloudy weather the battery could not charge fast.

Common mistakes encountered during the job was during the connection using cables. Since the cable used for the job had a single colour code (red) , it made the work a little slower as the positive and negative terminals were often interchanged.