There a several ways to measure solar energy: you can use simple kWh power meters or use the more advanced monitoring systems.
Monitor generated power regularly
When a solar power system generates electrical energy, it can be used to power your household loads, the power can be fed to the grid or it can be stored in battery banks.
The most common way to measure how much electricity is produced, is to install kWh power meters downstream of the solar panel, between the inverter and grid, or the inverter and the load.
Regularly monitoring the amount of electricity produced by your solar panel is a way to ensure that your solar system is working properly.
Depending upon your system configuration, you may need one or multiple meters.
The basics of electrical power and energy
Electrical energy is defined as the potential energy which is carried by rapidly moving electrons within an electrical conductor. It is measured in Joules (J). The flow rate of this electrical energy flows is called power. Power is measured in Watt (W).
When one joule of electrical energy is generated in one second, the power is said to be one watt. Higher units of measuring power are kilowatt (1 kW = 1000 W), megawatt (1 MW = 1000 kW) and gigawatt (1 GW = 1000 MW).
Electrical utilities use another unit for billing purposes which is called kilowatt hour (kWh). It is the equivalent to the amount of power consumed by a 1000 W load in one hour.
How does a kWh Power Meter work?
Electric power companies install electric meters to measure the amount of power consumed by its customers. A similar meter can be used to measure solar energy that a solar system is feeding to the grid.
The simplest electric meters have two electromagnets with a rotating disc in between them. One electromagnet is connected to the line side and the other to the load side.
The interaction of the two electromagnetic fields rotates the disc in such a manner that its rotation is equivalent to the current drawn by the loads. As the disc rotates, it turns a series of geared wheels that are connected to numeric or digital indicators on the meter’s front.
The reading of the indicators is the amount of electricity consumed by the loads.
How many power meters do I need to install?
Depending upon the configuration of your solar power system, you may need one or two meters. The installation of power meters is recommended as it helps you to keep track of your electricity consumption patterns.
For grid tied solar power system, generally two power meters are installed:
One is owned by the utility company and is installed right before the power enters your system and is used to measure the power which is drawn by the grid. The other is owned by the customer and is installed right after the solar panel array to measure the power produced by the solar system.
Monitoring systems to measure solar energy
Even though the use of kWh meters is a common way to register power consumption, nowadays more advanced monitoring systems can make your life a lot easier.
Instead of manually keeping track of the power meter, you can use monitoring systems and software to keep track of all statistics linked to your solar power system.