Solar Electricity for a Farm

In May 2018, I visited a farm overseas and installed a Photovoltaic System (900W) on the farm. They have no grid electricity supply.

Photovoltaic System for the Farm

The system proposed is a 900 Watts Photovoltaic System that can provide up to 2 KW of electricity to the farm. The daily usage has to be budgeted to ensure that the batteries storage is not fully discharged by excessive electricity usage.

System Specifications:

900 Watts Photovoltaic System (6 pieces of 150W Solar Panels)

Power Inverter, 24Vdc to 230Vac, 2,500 Watts

Lead Acid Batteries 12Vdc 200 AH – 4 pieces (Operating at 24 Vdc)

Budgeted Daily Energy Usage: approx 2,600 Watt-Hour per Day

Standby Battery Storage: 3 days

 

The Schematics for the Photovoltaic System is shown below.

The estimated energy usage for the farm based on their daily operations using the following electrical equipment and appliances:

1. Water Pump (500 watts) uses 3 hours daily
2. LED Lamps (10W x 5 pieces) uses 6 hours at night
3. Fan (40W x 2 pieces) uses 10 hours at night
4. Spot Light (10W) operate 12 hours at night for security

If the farm restricts the energy usage to the above duration, the photovoltaic system will be able to provide their daily energy needs.

The ampere meter shows the solar charging current of 18.7 Amps into the lead acid batteries.

A change-over switch between generator and solar allows easy switching between the two systems.

Donation of the Photovoltaic System.

• Photovoltaic System Cost – SGD 4,500
• Tools (Hammer Drill & Battery Operated Hand Drill) – SGD 160

In July 2018, the inverter had died. It was brought back to Singapore and send back to the shop to repair. It was found that all the fuses and MOSFET were burned. Still trying to understand what caused the inverter to die.

In October 2018, I bought a new inverter online, 2500W pure sine wave solar power inverter DC 12V 24V 48V to AC 110V 220V digital display. It cost me SGD$213.73.

Manage to get someone to bring over and install the inverter. The system is working again.

Install Photovoltaic Systems with 5KW Inverter at PKH Trang

In July/August 2017, PKH Maintenance team installed two Photovoltaic Systems at PKH Trang. 

One system (4.2KW PV) is located behind the classrooms with 30 solar panels (140Wp), 5KW inverter and 8 batteries with additional 20 solar panels (spare) unconnected. This is use for water pump operating from 8am to 4pm; House 1 & 2 from 6.00pm to 9.30pm; Classroom and Office during the day.

The other system (2.8KW PV) is located between the generator room and maintenance house with 20 solar panels, 5KW inverter and 4 batteries with 10 solar panels (spare) unconnected. This is use as spare and maintenance house (60w fan, 2 flourescent lamps and 14w night light).

In the past, PKH use a generator to power the power pump, 1 Km away at Chombok school, to draw water for PKH Trang Training Centre usage.

With this solar installation and also new wiring (thicker cables) to the water pump, PKH do no need to rely on the generator. Hence it helps PKH to save cost in operating the water pump. We have also included a MCB 13A at the output of the inverter to limit the maximum power usage to 3KW so as the inverter will not be damage by overload.

The block diagram wiring for the PV system located behind the classroom.

Inverter and Batteries Installation

The next PV system is located between the generator room and maintenance house.

Both systems are installed and functional.

We will install a KW-Hr energy meter in the PV system to measure the electricity usage. The electricity usage will be charge to PKH and the revenue earned will be use for maintenance and repair of the PV systems at Trang. Suggest the electricity charges be 15 cents (USD) per KW-Hr.

 

 


Thank God for his guidance and providence.