Netbilling, Law 21.118: how to sell your surpluses

Installing solar panels without understanding net billing is leaving money on the table: on days with low activity, when the system generates more energy than the business consumes, that energy isn't wasted if it's properly managed. It can be sold back to the grid and deducted from the electricity bill. This is how it works in Chile.

What is netbilling?

Netbilling is the mechanism established by Law 21.118, which regulates distributed generation for self-consumption. It allows a company or individual with their own generation system (primarily solar) to inject excess energy into the grid that they don't consume at that moment, and receive a compensation for that excess, which is deducted from their next electricity bill.

It’s different from the “net metering” model used in other countries, where compensation is provided for each kilowatt of energy injected and consumed. In Chilean netbilling, the excess energy is valued in monetary terms, at a price defined by the regulations, and that amount is deducted from the amount the company owes the distributor for the energy it consumed from the grid.

Who can find refuge.

Netbilling applies to distributed generation systems up to 300 kW in installed power. This covers virtually any small and medium-sized commercial solar project – from a 10 kWp system for an office to a 30 kWp system for a medium-sized facility, both well below the limit.

There’s no minimum power level required to accommodate – even a small system can generate surpluses and deduct them from the account, although the impact on weight/volume will be proportional to the size of the system.

How do you go about completing the procedure, in practice?

The netbilling process shouldn’t be something the business owner has to handle alone, directly with the distributor. It’s managed as part of the installation project.

1. System designwith power defined according to the measured consumption.
2. Request for connection Before the distributor, presented by the certified installer along with the project’s technical documentation.
3. Installation of a bidirectional meterwhich records both what the business consumes from the network and what it injects.
4. Launch.with the formal connection established and the system enabled to generate valued surpluses.

Why is the SEC certification important?

The entire process depends on the installation being certified by the Superintendency of Electricity and Fuels (SEC). Without this certification, the distributor will not approve the connection or enable net billing, regardless of how well the panels are installed. That’s why at Ditap Energía, we work with a certified SEC installer – Vicente López in Chile, Marcelo Arriada in Argentina – and not with unlicensed labor, even if it seems cheaper in the short term.

What does a business make from this?

Let’s consider a business with a 10 kWp solar system: on weekends or holidays, when the premises are closed but the sun is still generating, all of that energy is fed back into the grid instead of being wasted. This surplus, valued through net billing, appears as a credit on the following bill. Without net billing, the only way to utilize 100% of the generated energy would be to consume it at the exact moment it’s produced – something that’s not realistic for most businesses.

The step before the procedure.

Netbilling is the administrative aspect of a solar project, but it doesn’t replace technical evaluation: how much energy the system will generate, how much will be consumed, and how much will be left as excess depends on the actual consumption of the business and the amount of sunlight in the location. That evaluation, and the design of the system, including the netbilling process, is what the platform provides. Commercial solar.