Solar import, export and generation explained

Reviewed May 2026 against Octopus export guidance, GOV.UK Smart Export Guarantee guidance and Ofgem’s SEG explanation. The core principle has not changed: your solar app, smart meter and Octopus account can all be correct while showing different figures.

If your inverter says you generated 12 kWh today, your Octopus app says you imported 6 kWh and your export account shows 4 kWh, it is very easy to think one of those numbers must be wrong. Most of the time they are measuring different flows.

This guide separates the four figures people mix up most often: generation, import, export and self-consumption. Once those are clear, Octopus bills, export payments and solar apps usually make much more sense.

The four numbers in one sentence

• Generation is everything your panels produced.
• Import is what you still pulled in from the grid.
• Export is what you sent back out to the grid.
• Self-consumption is the share of your solar generation you used at home instead of exporting.

The key point is that these numbers do not compete with each other in a simple one-line total. A home can generate solar at lunchtime, export some of it, then import electricity later that same evening.

Start with the direction of the electricity

Think of your home as a junction with three places electricity can go.

1. Your panels generate electricity.
2. Your home uses some of it straight away.
3. Any surplus either charges a battery or leaves the house as export.
4. If your home needs more than the panels and battery can provide, the gap comes in as import from the grid.

That means import and export can both happen on the same day without anything being wrong. They just happen at different moments.

What generation means

Generation is the total output from your solar panels, usually shown in your inverter app or monitoring portal.

If your inverter says you generated 14 kWh today, that tells you how much electricity the panels produced before it was split between your home, your battery and the grid. It does not tell you how much you avoided buying from Octopus, and it does not tell you how much Octopus will pay you for export.

Generation is mainly useful for:

• checking whether the system is producing as expected
• comparing sunny and cloudy days
• sizing whether your battery or usage pattern suits your array

What import means

Import is electricity you bought from the grid. This is the number that matters for your main Octopus supply bill.

If your home used 18 kWh in a day and your panels covered 11 kWh of that directly, you still imported the remaining 7 kWh. On a standard tariff those imported units are billed at your import rate, which might be around 24.7p/kWh on a price-capped tariff. On a time-of-use tariff, the cost also depends on when the import happened.

Import usually rises:

• overnight, when the panels are not producing
• on dark winter days
• when high-demand appliances run after sunset
• if you deliberately charge a battery from the grid on a time-of-use tariff

What export means

Export is the electricity that left your home and went back to the grid. This is the figure used for SEG, Outgoing Octopus or another export tariff.

If your panels are producing more than the house is using at that moment, the extra electricity has to go somewhere. If the battery is already full, or not set to charge, the spare energy is exported.

Export is not a bonus copy of your generation. It is the unused part of your generation after your home and battery have taken what they can. GOV.UK and Ofgem both describe SEG payments as being based on exported electricity, not total solar generation.

For Octopus export tariffs, there is also an account setup detail that confuses people. Your import supply has an import MPAN. Export payments normally need an export MPAN as well, and Octopus says it applies to the DNO for that during Outgoing setup. That can make the export side feel like a separate account even though it is linked to the same home.

What self-consumption means

Self-consumption is the part of your solar generation that stayed useful inside the home.

A simple working formula is:

self-consumption = generation - export

So if your panels generated 12 kWh and you exported 5 kWh, you self-consumed 7 kWh.

That 7 kWh is often the most financially valuable part of your solar setup, because each unit you use yourself avoids buying a unit from the grid at your import rate. That can be worth more than a basic export payment, especially if your import tariff is much higher than your export rate. It is one reason people talk so much about running appliances in sunny hours or adding a battery.

A simple day worked through

Imagine this day:

• Panels generate 16 kWh
• Your home uses 11 kWh in total
• You export 6 kWh
• Your battery starts empty, stores some lunchtime surplus and discharges in the evening

What happened?

• Generation = 16 kWh
• Export = 6 kWh
• Self-consumption = 10 kWh
• Your home used 11 kWh overall, so the final import was 1 kWh

Nothing there is contradictory. The battery helped shift some solar into the evening, which reduced import, but the house still needed 1 kWh from the grid later on.

Why the Octopus app, inverter app and meter do not always match exactly

Even when everything is working normally, the numbers can look out of sync because each system has a different job.

The inverter app usually shows generation first. Some inverter platforms also estimate household use, battery charge and export, but they are still not the billing source.

Your smart meter is the authoritative source for billed import and metered export. If you are on an export tariff, it is the meter’s import and export registers, plus any registered export MPAN, that matter for payments.

Your Octopus account reflects the supplier side. It can lag behind the inverter, especially if half-hourly data has not landed yet. It can also separate your import supply and export payments in ways that make the picture feel fragmented.

If the mismatch is between app usage and billing totals rather than solar concepts, read our guide to why app usage and bills do not always match.

Where to check each figure

Figure	Best place to check	What it helps with
Generation	Inverter app or solar portal	Is the system producing properly?
Import	Octopus bill, Octopus app, smart meter import register	What are you buying from the grid?
Export	Export account, export MPAN, smart meter export register	What will Octopus or your SEG supplier pay you for?
Self-consumption	Usually calculated from generation minus export	How much solar are you keeping and using?

Common confusion points

“My panels generated 10 kWh, so why did I still import 8 kWh?”

Because generation and import happen across the whole day, not in one instant. If most of your use was in the evening, you may still have needed the grid after sunset.

“My export payment is much lower than my generation figure”

That is normal. Export only covers the surplus you did not use yourself. A household with strong daytime usage may generate 10 kWh and export only 2 or 3 kWh.

“My battery means I should never import, right?”

Not necessarily. A battery reduces import, but winter days, overnight loads and heavy evening use can still force some grid import. Battery settings also matter.

“If I charge my battery from the grid overnight, is that generation?”

No. That is still import. It may be a smart move on Agile, Go or another time-of-use tariff, but it is not solar generation.

How batteries change the picture

A battery does not create more generation. It changes the timing.

Without a battery, surplus lunchtime solar is often exported immediately. With a battery, some of that surplus can be stored and used later, which lifts self-consumption and cuts evening import.

That is why two homes with identical panels can end up with very different bills. The battery changes how much of the solar output stays in the house instead of spilling out to the grid. Our guide to battery storage strategies goes deeper into that side.

Which number matters most financially?

For most Octopus solar homes:

1. Self-consumption is the most valuable driver of savings.
2. Export is the next piece, especially if you are on a strong export tariff.
3. Generation tells you system performance, not direct bill savings on its own.
4. Import shows what you still had to buy after solar and battery help.

That is why the best solar setup is not always the one with the highest generation alone. It is the one that pairs decent generation with a tariff and usage pattern that makes the most of it.

What to read next

• Solar panels with Octopus
• Export rates explained
• Battery storage strategies
• Reading your smart data
• Understanding your Octopus bill

If you are still choosing between import tariffs as well as export deals, the wider solar guide is the best place to compare the main Octopus routes.