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Where Does Excess Solar Power Go? [What Can You Do with It?]

Tim Carter
Written by Tim Carter Last Updated: July 25, 2022

All solar power systems are based on the same fundamental ideas. Solar panels first convert solar energy, or sunlight, into DC electricity with the help of the photovoltaic (PV) effect. The DC power can be converted into AC power using a solar inverter or stored in a battery to power home appliances.

We can store unused solar energy in a variety of ways. We can store it in battery storage systems or send it to the grid for credits, depending on the system type (on-grid, off-grid, hybrid solar system).

Table of Contents

What Are Solar Power Systems?

There are three main types of solar power systems.

  • Grid-tie or grid-feed systems are typical names for on-grid solar systems.
  • Off-grid, often known as a stand-alone power system (SAPS), and
  • A hybrid solar power system with battery storage that is linked to the grid

Modern solar panels use photovoltaic cells, often known as PV cells, to generate direct current (DC) power from sunlight.

The PV cells in each solar panel are wired to one another and to surrounding panels.

Notably, photovoltaic cells use sunlight or other forms of irradiance to produce energy rather than heat.

Solar panels, also known as solar modules, are typically connected to create solar arrays.

The amount of solar energy is influenced by several factors. These factors include the solar panels’ orientation and tilt angle, efficiency, and any losses caused by ambient factors like temperature, dirt, or shading.

Given the wide range of solar panel manufacturers out there, it is critical to know which solar panels are the best and why.

The amount of electricity that solar panels can still produce under cloudy and foggy situations depends on how much light can get through the clouds, how thick they are, and how high they are.

Peak Sun Hours (PSH) is a word used to describe the amount of solar irradiation, sometimes referred to as light energy, that is averaged across a day.

The PSH, or average daily sunlight hours, was mostly determined by geography and season.

Solar panels must be transformed from the direct current (DC) electricity they generate into alternating current (AC) in order to power our homes and places of business.

This is mostly the job of the solar inverter.

A “string” inverter system connects solar panels in series, transferring DC power from the panels to the inverter, which transforms it into AC power.

A unique micro-inverter is placed at the back of each panel in a microinverter system.

The panel still generates DC, but it is converted to AC on the roo before being fed directly to the electrical switchboard.

In more advanced string inverter systems, each solar panel has a small power optimizer on the back.

Each panel may be tracked and managed independently by a power optimizer, assuring maximum efficiency at all times.

Lithium-ion batteries can frequently supply up to 90% of their available capacity each day, in contrast to lead-acid batteries, which typically only supply 30 to 40% of their total capacity each day in order to prolong battery life.

Off-grid solar systems require specialized off-grid inverters and battery systems with the capacity to store electricity for two or more days.

Hybrid grid-connected systems only require a battery large enough to store energy for 5 to 10 hours (overnight); hybrid (battery) inverters are less expensive; however, this depends on the application.

In a conventional grid-tied solar system, the solar inverter sends AC power to the switchboard, where it is accessed by your home’s many circuits and appliances.

Net metering is using an energy meter to either send any extra electricity generated by a solar system to the grid or, with a hybrid system, to store it in batteries.

However, under a system known as “gross metering,” all solar energy is exported to the electricity grid in some countries.

Hybrid systems can export surplus energy and store it in batteries.

During a blackout or grid breakdown, some hybrid inverters might also be connected to a different backup switchboard.

The On-Grid System

An on-grid or grid-tied system is by far the most frequent and well-liked solar system used by homes and businesses.

These systems use solar inverters or micro-inverters to run without the use of batteries by connecting to the public electrical grid.

Any excess solar energy you generate can be exported to the electrical grid for credits or feed-in tariffs (FiTs).

On-grid solar systems, unlike hybrid systems, cannot function or generate electricity during a blackout because of safety issues.

Blackouts normally occur when the electrical grid is malfunctioning.

Therefore, it would be risky for the employees who were fixing the network’s fault if the solar inverter was still producing electricity to a malfunctioning grid (s).

Most battery-powered hybrid solar systems can island—or quickly cut off from the grid—and continue to supply some electricity during a blackout.

If more batteries are required, systems that are connected to the grid can do so.

A solar array that already exists might be supplemented with well-liked AC battery solutions like the Tesla Powerwall 2.

In a system that is connected to the grid, this happens in the meter when electricity reaches the switchboard.

If you are importing or exporting power, the meter measures the extra solar energy (purchasing).

Metering practices vary between states and countries around the world.

In some states, your meter records the total amount of solar power produced by your system. Your electricity will therefore pass via your meter before it reaches the switchboard as opposed to following it.

In certain places, the customer is billed (or given credit) for the net quantity of power used over the course of a month or year (currently in California).

The electricity that is sent to the grid can subsequently be used by other consumers.

You will start importing or using electricity from the grid when your solar system is not running or when you are using more energy than your system is generating.

Off-Grid System

Since an off-grid system is not wired into the power grid, battery storage is necessary.

Off-grid solar systems must be properly planned so that they can produce enough electricity all year long and have adequate battery storage to fulfill the needs of the home, even during the darkest months of the year when there is typically significantly less sunlight.

Off-grid systems are typically only required in more distant places that are far from the electrical grid because they are substantially more expensive than on-grid systems because of the high cost of batteries and off-grid inverters.

Off-grid solar battery systems are currently becoming more and more popular, even in cities and towns, as the price of batteries is plunging.

In smaller-scale DC-linked systems, the battery charging is controlled by a solar charge controller, and the DC power is then converted to AC and transmitted to your home’s appliances via an off-grid converter.

There is no public electrical grid in an off-grid setup.

Any extra solar energy left over after your property’s appliances use will be delivered to your battery bank.

Additionally, the solar system will stop supplying electricity once the battery is full.

Your appliances will take electricity from the batteries when your solar system is not operating (at night or on overcast days).

You will typically require a backup power source, such as a backup generator or gen-set, for periods of the year when the batteries are low on charge and the weather is severely gloomy.

The generator set should be large enough to power your home and charge the batteries at the same time (measured in kVA).

Hybrid Systems

Modern hybrid systems come in a variety of shapes and combinations and combine solar power and battery storage.

Battery storage is becoming more affordable, allowing systems that are already plugged into the power grid to use it as well.

This entails having the capacity to store solar energy produced during the day and use it at night.

The grid serves as a backup in case the energy in storage runs out, giving consumers the best of both worlds.

Hybrid systems can also use inexpensive off-peak electricity to charge the batteries (usually after midnight to 6 am).

Hybrid systems can be designed in a variety of ways, but for now, we will keep it straightforward.

See our comprehensive guide to home solar battery systems for additional information on the various hybrid and off-grid power solutions.

In a hybrid system, any extra solar energy will be delivered to the battery bank once it has been consumed by the appliances on your property.

Additionally, the battery bank will stop receiving electricity from the solar system after it has been fully charged.

When electricity prices are often at their highest, in the evening peak, the battery’s energy can then be discharged and used to power your home.

Once your batteries are fully charged and your utility permits it, excess solar electricity not needed by your appliances may be used, depending on how your hybrid system is configured.

Your appliances will start pulling power from the grid when your solar system is not in use and if you have used up all the energy in your batteries.

What Happens to Solar Power When Batteries are Full?

What will happen if the amount of electricity generated by the solar panels is higher than the load (or the amount of energy required by your appliances)?

Here, the inverters or charge controllers will restrict their power output to what the load requires, reducing the maximum amount of solar power that could be produced.

The equipment will not turn the extra solar energy into electricity any further.

How Do We Avoid Wasting Excess Solar Power?

You can wind up wasting the extra solar power if there is an excess of solar energy and not enough demand to use the electricity.

What can you do with the additional energy generated by solar panels?

1. Increase the number of battery banks

Increasing the number of battery banks is an additional solution. Your power system’s stability will improve if you increase your energy storage capacity. You will fill up more of your batteries for future use as opposed to wasting the extra solar energy.

You will be more assured about expanding your company and taking on additional loads if you do this. To avoid any issues, just watch how you manage your power usage.

2. Give away the surplus solar energy

If you have more energy than you need, sharing it with others is always a good thing.

You can put up a charging station so that people can bring their batteries in and use your extra electricity to charge them for nothing instead of letting it go unused.

You might consider outdoor enthusiasts, RV owners, and other groups.

Or, you might donate it to organizations that support less fortunate individuals and groups. They will undoubtedly profit from your kindness whenever they are close to your power plant.

What Happens with Excess Solar Power on On-grid Battery Systems?

So where does extra solar energy for on-grid installations go?

The technology can feed the additional solar energy into the national electrical grid if the battery banks may connect to it.

However, you must know each electric company has its own policies and guidelines that must be followed when importing solar electricity into its system.

If net metering is required, you can send the extra solar energy to the public grid and receive an energy credit that you can use later that night.

The utility may carry over any excess solar energy you produce for the entire month toward the following account.

You can make some money based on how much you export and how much the grid company will pay you per kWh for your solar energy if it imposes feed-in tariffs.

Additionally, it implies that they have power over how much your extra solar energy costs.

They will succeed if they pay a hefty amount to purchase it.

But some regions charge relatively little for exported solar energy, which will not be very helpful for homeowners with sizable solar power installations.

It is imperative to perform your research and get this knowledge from your local electricity utility.

Can Solar Panels Overcharge The Batteries?

Solar panels can overcharge their batteries in smaller systems with no electrical safety measures.

The output wires of solar modules are occasionally connected directly to the terminals of batteries.

The problem is that relying solely on solar panels to determine whether batteries are full is impossible.

Overcharging occurs when the modules continue to supply the batteries with electricity past their capacity.

Your battery banks may sustain significant damage as a result, making them potentially useless.

That is why effective system design and security measures are required. It will be simple to resolve this issue if you have a charge controller.

Related: Can You Use Solar Panels Without Batteries? [Are Batteries Necessary?]

Final Thoughts

Using the photovoltaic (PV) effect, solar panels first convert solar energy, or sunshine, into DC power.

A solar inverter or a battery can convert the DC power into AC power, which can then power home appliances.

There’s much you can do with excess solar power. You can store unused solar energy in many ways.

Depending on the type of system, we can either send it to the grid for credits or store it in battery storage systems (on-grid, off-grid, hybrid solar system).


Tim Carter
Tim Carter

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