Net metering or net billing today?

Net metering or net billing are not simply two different names for the same photovoltaic system. They define how the energy you produce is valued, what your excess generation is worth, and how critical battery storage becomes. For a residence, a business, or an agricultural supply, the wrong choice of power and equipment can significantly increase the payback period.

The essence is simple: photovoltaics reduce the bill when the energy produced is consumed at that moment. When it is not consumed, the rules of the respective scheme decide how it will be credited. That's why proper planning starts with actual consumption profiles and not from a general rule like "install as many panels as the roof can hold."

What was net metering

Net metering compared, on an energy basis, the kilowatt-hours a supply absorbed from the grid with the kilowatt-hours the photovoltaic system fed into it. Excess generation acted as an energy credit for future consumption, according to the terms of the relevant agreement.

This model was particularly suited to consumers with seasonality. A holiday home, for example, could produce a lot in spring and summer and utilize the energy credit when consumption increased. Similarly, an agricultural installation could balance different periods of production and irrigation.

Today, for new applications, the market is moving towards net billing and self-consumption. This does not mean that existing net metering contracts automatically cease to be valid. However, it does mean that anyone planning a new project now needs to evaluate its economic performance under current rules.

How net billing works

In net billing, energy produced and consumed simultaneously in the building has the greatest economic value. Every kilowatt-hour you don't buy from your supplier avoids the corresponding supply cost and part of the related charges affected by consumption.

Excess energy is exported to the grid and compensated through a mechanism that is not the same as the cost of purchasing electricity. Simply put, it is not profitable to design a system assuming that midday surplus production is worth the same as the kilowatt-hour you will need from the grid in the evening.

This difference changes the logic of the study. The goal is not only maximum annual production, but high synchronized self-consumption: that is, utilizing as large a percentage as possible of your solar production within your installation.

A practical example

A residence that consumes mainly during the evening hours may have excellent annual production from the panels, but low direct consumption at midday. Without a battery, much of the production will go to the grid. With properly sized storage, part of this energy is transferred to the household's peak hours.

Conversely, an office, shop, or small craft business that operates from morning to afternoon often has naturally high self-consumption. In this case, the photovoltaic system can perform very effectively even with a smaller battery or without a battery, provided the load profile confirms it.

Net metering or net billing: the essential difference

The main difference is not technical, but economic. In net metering, the focus was on the energetic balancing of incoming and outgoing kilowatt-hours. In net billing, the focus is on the value of instantaneous self-consumption and the rational management of excess.

Precisely for this reason, the LiFePO4 battery acquires a different role in the design. It is not necessary for every project and should not be added mechanically. However, it can substantially improve the economics of a system when consumption is shifted to the afternoon and evening hours, when there are frequent grid outages, or when the owner wants backup operation for critical loads.

The battery does not create additional solar energy. It increases the utilization of already produced energy by storing it for later. Whether this value justifies the additional cost depends on the daily consumption cycle, the available photovoltaic power, the desired autonomy, and backup requirements.

When storage is beneficial

Storage is usually more sensible when consumption remains high after sunset. Families who use a kitchen, air conditioning, water heater, electric vehicle charging, or a heat pump in the afternoon have a different profile than a house that is empty all day and consumes very little at night.

It is also particularly useful in holiday homes, island areas, and installations where continuity of supply is valued. Here, caution is needed: not all hybrid inverters offer the same backup capability. Energy storage for economic energy shifting is one thing, and actual backup operation during a grid outage, with proper management of critical loads and appropriate electrical design, is another.

For a business, the battery can also serve operational goals. A load with large instantaneous peaks, sensitive equipment, or the need for uninterrupted operation requires a power study, not just a capacity study. The choice of inverter, the possibility of parallel operation, and the charging strategy are crucial details.

Correct sizing does not start with square footage

Available roof area is important, but not sufficient to determine the size of the project. A technically sound proposal examines bills, hourly consumption where data is available, future needs, and supply limitations.

If you are planning a heat pump, an electric car, a business expansion, or a new irrigation need, these must be integrated from the beginning. Otherwise, a seemingly economical system may prove too small in a few years. On the other hand, oversizing without corresponding consumption creates more energy export than needed.

The quality of the subsystems also has a direct impact on the result. A reliable inverter, properly selected panels, quality bases, appropriate DC and AC protections, and certified installation protect the investment for years. In hybrid projects, inverter and battery compatibility is not a catalog detail but a basic prerequisite for safety, warranty, and predictable operation.

What to ask before deciding

A net billing offer must clearly explain what it includes: photovoltaic power, estimated production, consumption assumptions, self-consumption percentage, equipment, electrical work, and future expansion possibilities. If it includes a battery, ask for the usable capacity, charging and discharging power, operation during a grid outage, and which loads will be covered.

Avoid payback promises that do not mention consumption, tariff, and usage. The same system can be an excellent investment for a store with daily operation and a mediocre choice for a residence that consumes almost exclusively at night. Numbers are only valuable when based on real data.

At Hellenic Energy, the free technical study starts from exactly this basis: to find the combination of photovoltaic, inverter, and storage that serves your consumption, not a standardized package. The right investment is not the one with the most panels or the largest battery, but the one that converts your solar production into measurable cost reduction and reliable energy freedom.