Net Metering is a service mechanism that allows the export of electricity generated by solar photovoltaic (PV) systems to the grid (PLN network). PLN installs a special utility meter called the Exim (Export-import) meter on solar PV systems, which enables net metering. The Exim meter measures and records the energy flow between the home and the grid, which may include import (electricity from grid to home), or export (home to grid).
Solar panels will generate more power during the day when the weather is sunny. Whenever there is excess power unused by the homeowner, electricity will be sent to the grid. This is the export part of net metering. Through this, homeowners receive financial gain since any exported electricity will offset their monthly utility (PLN) bill. On cloudy or rainy days, the solar PV system will produce less electricity since there is less solar radiation. However, if a household needs additional electricity, it can be imported from PLN.
Net Metering Cost Savings Example:
Most homeowners have a PLN meter capacity of 1,300 VA - 3,500 VA, meaning that the PLN electricity tariff is Rp. 1,444.70 / kWh (as of Ministry of ESDM [Energi dan Sumber Daya Mineral] Regulation Number 3 of 2020).
For this example, let’s assume a household uses 1,300 VA, with the tariff Rp. 1,444.70 / kWh. At the end of the first month of the year, a homeowner receives a bill stating that they have used 210 kWh of electricity throughout January.
SCENARIO A (Total Electricity Bill with no PLTS [Pembangkit Listrik Tenaga Surya]):
The total utility payment is calculated by multiplying 210 kWh with the monthly tariff of Rp. 1,444.70/ kWh, resulting in Rp. 303,387.00.
SCENARIO B (Total Electricity Bill with PLTS):
Now assume the homeowner has a 1kW On-Grid solar PV system installed which generates about 100 kWh per month. If the house uses the entire 100 kWh every month, then the homeowner pays a sum of 210 kWh minus that 100 kWh, which is 110 kWh. The total would be Rp. 158,917.00 (110 kWhRp. 1,444.70). This means that the homeowner has saved about Rp. 144,470.00 (Rp. 303,387.00 - Rp. 158,917.00), approximately half of the total value if a solar PV system wasn’t installed.
SCENARIO C (Total Electricity Bill with PLTS and kWh Export):
Lastly, if the solar PV system exports 25 kWh of the 100 kWh that it produces, the calculation would follow the following formula (as of Ministry of ESDM Regulation Number 3 of 2020):
Customer Electricity Bill (kWh) = Total energy imported from the PLN grid to consumer per month (“kWh Import”) - 65% of total energy exported by the consumer to the PLN grid per month (“kWh Export”)
Therefore, the electricity exported to PLN will be calculated monthly at 65% of the PLN tariff. If the total energy imported is 100 kWh, and 25 kWh is exported to the PLN grid, the customer’s electricity bill (kWh) will follow the calculations below:
210 kWh (total energy used) - 75 kWh (energy consumed from PLTS) - 65%25 kWh (kWh Export), which is 118.75 kWh.
Multiplied by the tariff, the homeowner would have to pay Rp. 171,558.00 (118.750 kWhRp. 1,444.70) for January.
The homeowner has saved about Rp. 131,829.00 (Rp. 303,387.00 - Rp. 171,558.00).
Ideally, from the 3 scenarios, we would want to have a solar PV system installation with no exported electricity. This is why proper system design and engineering is necessary before the installation process. On average, by installing a solar PV system, it is proven that residents can save up to 20-50% of their monthly PLN bill depending on the location and capacity of the system.
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