Solar Generation vs Export: Why Don’t the Figures Match?

If your inverter app says your solar panels generated 25 kWh today but your smart meter only recorded 8 kWh of exports, it doesn't usually mean there's a problem with your system.

From our experience installing solar and battery systems, this is one of the most common questions homeowners ask. Many people expect their generation and export figures to match, but they're measuring different parts of the energy flowing around your home.

Once you understand where your solar electricity goes first, the difference between the figures becomes much easier to explain.

What's the difference between solar generation and solar export?

Solar generation is the total amount of electricity your panels produce.

Solar export is the electricity your home doesn't use and sends to the grid.

Because your home uses solar power before any surplus is exported, these figures will almost always be different.

Where does your solar electricity go?

Your solar system automatically sends electricity where it's needed first. You don't need to decide where the energy goes.

In most homes, solar electricity is used in this order:

1. It powers appliances and electrical devices in your home.

2. It charges your battery, if you have one and it isn't already full.

3. Any remaining electricity is exported to the grid.

From our experience, homeowners are often surprised by how much solar electricity is used around the home before any surplus is exported.

Why is my export lower than my generation?

For most households, this is exactly what you'd expect.

While your panels are generating electricity, your home is using power at the same time. Everyday appliances such as your fridge, freezer, broadband router and heating controls all consume electricity throughout the day.

If you're using larger appliances like a washing machine or dishwasher while your panels are generating, even more of that electricity stays within your home instead of being exported.

How does a battery affect the figures?

Battery storage is designed to increase how much of your own solar electricity you use.

Instead of exporting every spare unit of electricity to the grid, your system stores surplus energy in the battery so it can be used later, such as during the evening. As a result, export figures are often lower because more of your solar generation stays within your home.

From our experience, homeowners usually notice the biggest difference between generation and export after adding battery storage, as they're relying less on exporting surplus electricity.

A simple example

Imagine your solar panels generate 20 kWh of electricity during the day.

• 8 kWh powers your home.

• 7 kWh charges your battery.

• 5 kWh is exported to the grid.

Your generation is still 20 kWh, but your export is only 5 kWh because the remaining electricity has already been used or stored. Nothing has been lost, it's simply been used in a different way.

Even after understanding this, you may still notice small differences between the figures shown by your inverter, battery and smart meter. In the next section, we'll explain why that happens.

Why do my inverter, battery and smart meter show different figures?

Many homeowners compare the figures shown in their inverter app, battery app and smart meter expecting them to match. In reality, each one is measuring a different part of your home's electricity, so it's completely normal for the numbers to vary.

For example, your inverter might show 18 kWh of solar generation, your battery could record 6 kWh of charging and your smart meter might show 4 kWh exported. These figures aren't contradicting one another. They're simply recording different stages of the same energy journey.

From our experience installing solar and battery systems, understanding what each device measures is often all that's needed to explain why the figures don't match.

Does battery discharge count as solar generation?

No.

When your battery powers your home later in the day, it isn't creating new solar electricity. It's supplying energy that was generated earlier and stored for later use.

It's easy to assume battery discharge should increase your solar generation figure because the electricity originally came from your panels. However, that energy has already been counted once, at the point it was generated. Using it later doesn't increase your generation total or your export figure.

From our experience, this is one of the most common areas of confusion for homeowners with battery storage, particularly when they're comparing different apps.

Why don't the figures match exactly?

Even when everything is working correctly, it's common to see small differences between your readings.

That's because your inverter, battery and smart meter aren't all measuring the same thing at the same time. Each device records information independently and may update its data at different intervals. Some systems also round figures differently, which can create small variations when you compare them.

From our experience, these differences are usually minor and are simply part of how separate monitoring devices record your home's electricity use.

Looking at the whole picture

No single figure tells the complete story of how your solar system is performing.

Your generation figure shows everything your panels produce. Your home then uses some of that electricity, your battery may store some for later and only the remaining surplus is exported to the grid. Looking at these figures together provides a much clearer understanding of how your system is working than comparing any one number in isolation.

From our experience, homeowners are often reassured once they understand that different figures don't mean something has gone wrong. In most cases, they simply show that your solar electricity is being used efficiently around your home before any excess is exported.

Understanding your solar data with confidence

Understanding the difference between generation, household use, battery storage and export makes it much easier to interpret your solar data.

At iHeat, we help homeowners understand not only how solar panels generate electricity, but also how that energy flows through their home. Explaining what the different figures mean is part of helping you get the most from your system and understand its performance with confidence.

If you're considering solar panels with battery storage, our team can help you choose a system that's designed to maximise self-consumption while giving you a clearer picture of how your home's energy is generated, stored and used.