What Happens to Unused Electricity Generated by Solar Panels on a Home?

An outstanding question that has intrigued many homeowners with solar panels is what happens to the unused electricity they generate. Currently, several methods are available to handle this excess energy, ranging from net metering programs to battery storage systems.

Current Methods and Issues

Without a method of storage, such as a battery, the unused electricity is either sold back to power companies at inflated prices, leading to increased costs for rate payers. This often happens when renewable sources like solar and wind cannot meet demand during times of low generation, such as at night or when the wind is still. These power companies, in turn, have to buy excess electricity from fossil fuel plants at high costs, which is not an efficient or sustainable solution.

Technical Insights

When there is no load, there is no movement of electrons. This means that in the absence of a connected electrical load, the solar panels simply generate a voltage but no current. As a result, untapped solar energy is essentially wasted. However, there are technical considerations even when there is a load present. For example, in a well-functioning electrical system, there is always some current flow, albeit minimal, due to the resistance of the components in the system such as controllers and wiring.

Options for Managing Unused Electricity

The specific mechanism for handling unused electricity from solar panels depends on the local regulations and the type of solar system installed. Here are some common methods:

Net Metering

What It Is: Net metering allows homeowners to send excess electricity back to the grid and receive credits on their electricity bill. This system helps balance the energy usage during periods when solar generation is low, such as at night.

How It Works: When a home generates more electricity than it consumes, the excess can be exported back to the grid. The utility company measures this excess in kilowatt-hours (kWh) and credits the homeowner's account for this amount. This credit can be used to offset future energy costs.

Feed-in Tariffs (FiTs)

What They Are: Feed-in tariffs are financial incentives where homeowners are paid a fixed rate for the electricity they generate and send back to the grid.

How They Work: In regions that offer FiTs, homeowners can earn a guaranteed income for the amount of electricity they produce, regardless of whether it is used on-site or exported to the grid. This can provide a steady income source for those with solar systems.

Battery Storage Systems

What They Are: Battery storage systems capture excess electricity generated during peak production times and store it for later use.

How They Work: Excess electricity during sunny days is stored in batteries for nighttime use or during overcast periods. This not only allows the homeowner to use more of their own generated power but also reduces reliance on the grid, potentially leading to significant savings on electricity bills.

Grid Supply and System Limitations

In areas without net metering or battery storage options, the excess electricity is often simply fed into the grid without any compensation. Although this method is simple, it is neither efficient nor financially beneficial for the homeowner. Additionally, in some cases, if a solar system produces more energy than can be used or stored, the inverter may automatically shut down to prevent overloading the system, creating efficiency losses.

The specific mechanism and policies for managing unused electricity are influenced by local laws, regulations, and the type of agreement the homeowner has with their utility company. Therefore, it is crucial for homeowners to stay informed about these options and regulations in their area.

Conclusion

Understanding the fate of unused electricity from solar panels is crucial for homeowners looking to maximize the benefits of their solar systems. By utilizing net metering, feed-in tariffs, or battery storage, homeowners can ensure that more of the solar energy they generate is used, reducing dependency on the grid and ultimately saving money. As technology and policies continue to evolve, the future looks promising for more efficient and sustainable energy management practices.