A solar monitoring app shows what your panels make, what your home uses and what goes to or from the grid. On a bright day, generation should climb towards midday and fall away in the evening. If it stays flat, or sits far below the same hour last week, call your installer.

Most apps use the same few lines, though the names differ by brand. This guide explains each one in plain terms, what a normal day looks like and which patterns point to a fault. It sits within our hub on solar panel maintenance and lifespan.

The numbers your app shows

Every app is a little different. Even so, most show the same four things. Learn these and you can read almost any screen.

  • Generation. The power your panels make right now, or the total for the day.
  • Consumption. The power your home is using.
  • Import. Power you pull from the grid because the panels cannot cover your use.
  • Export. Spare power that goes to the grid.

Many apps also show a fifth line for battery charge and discharge. If you have a battery, you will see it charge from spare solar and release power later. Our guide to solar battery cost and sizing explains how that works.

kW and kWh are not the same

This trips up many owners, because the two sound alike. A kilowatt (kW) is a rate, like speed. A kilowatt hour (kWh) is an amount, like distance. If your panels make 2 kW for 3 hours, that is 6 kWh.

Energy Saving Trust uses a related unit, kilowatt peak (kWp). It is the most power a system can make in ideal conditions. Its average home system is about 4.5 kWp. Your real output will almost always sit below that figure, because ideal conditions are rare.

What a healthy day looks like

On a clear day, generation draws a smooth hill shape, since the sun rises and sets in an arc. It starts low in the morning and peaks around midday. Then it falls through the afternoon.

A roof facing east and west gives a flatter, wider shape, because each side peaks at a different time. Our post on east-west and flat roof solar panels explains why. On a cloudy day, the hill is lower and bumpier, but it should still exist.

Seasons change everything

Do not panic in winter. Energy Saving Trust says panels work in winter but make less power, because days are shorter, cloud is more likely and the sunlight is less intense. For this reason, compare December with last December, not with June. Our post on solar panels in winter shows what to expect.

Reading generation against use

The gap between the generation line and the consumption line tells the story, because it shows where each unit goes. When generation is higher, the spare power goes to a battery or to the grid. When it is lower, you import.

Many people are surprised by how much they export. Energy Saving Trust describes one household whose panels made about 3,100 kWh in a year. Only about 40 percent of it was used at home or in the car. Your own split will depend on who is home and what runs at midday.

Why self-use matters

A unit you use saves you the price of buying one. Ofgem says the average default rate is 26.32p per kWh from 1 October 2026. Energy Saving Trust says export typically pays around 12p. So an exported unit is usually worth less than a unit you use.

Use the app to find your gaps. If export is high at midday, shift the washing machine or dishwasher to run then. Our guide on how to use more of your own solar power lists more ideas.

Signs that something is wrong

Most apps give you early hints, so look for these patterns.

  1. A flat line on a sunny day. The inverter may be off or in fault. Check for a light on the unit, and check the isolator switch.
  2. A sudden drop that stays low. One panel or string may have failed, or new shade may have appeared.
  3. A slow slide across years. Some of this is normal ageing. Our guide on how long solar panels last explains it.
  4. A dip at the same time each day. This often points to shade from a chimney, tree or neighbour’s roof.
  5. No data at all. The Wi-Fi link may have dropped. The panels may be fine, so reconnect the inverter to your router first.

Do not open the inverter or climb on the roof, because both are unsafe. Look at the unit from where you can safely see it. Then contact your installer with a screenshot and the dates.

Check your inverter for alerts

Energy Saving Trust says some inverters have online monitoring and can warn you by email if the system fails. Check that alerts are on, and that the email goes to an address you read. Our guide to solar inverters explained covers what the inverter does and why it is the part that fails first.

Comparing against your installer’s estimate

Your quote probably included a yearly generation estimate, which gives you something to test against. The MCS installation standard (MIS 3002 issue 6.0) asks owners to check that recorded generation is not falling. It also asks visiting contractors to check that generation matches the prediction.

However, the standard also treats the estimate as guidance for the first year only, not a guarantee. A fair test needs a full year of data. A single dull month tells you very little.

How to keep a simple log

You do not need a spreadsheet. For example, once a month, note the generation total for the month. Then, once a year, compare it with last year. A fall of a few percent can be weather. A bigger fall deserves a call. Our guide to cleaning and maintaining solar panels covers the first thing to try, which is a safe check from the ground.

App figures and your meter

Your app and your meter can disagree. The app reads the inverter, while the meter is a separate device. Small gaps are normal, because each measures in its own way and at its own points.

For export payments, the meter is what counts. Ofgem’s guidance says payment rests on a meter reading, and the supplier pays for each unit it records. As a result, treat the app as a guide and your bill as the final word. If the two differ by a lot over a full year, ask your installer and your supplier to check the set-up.

Our guide to the Smart Export Guarantee explains which meter you need. It also shows how to compare rates, which is worth doing each year.

Linking your app to other devices

Many apps now connect to other kit, while others stand alone. A hot water diverter can show how much surplus it sends to the cylinder. Our post on solar diverters for hot water explains how they work. An electric car charger can also show solar charging in the same screen, and our guide to charging an electric car from solar panels covers that.

A heat pump may have its own meter and app. Our post on solar panels and heat pumps explains how the two work together. Time-of-use tariffs add another layer, because the price changes through the day, as our guide to time-of-use tariffs with solar and a battery explains.

If your tools do not talk to each other, ask your installer before you add more. Our hub on choosing a solar installer explains what to ask about aftercare. Our hub on how solar panels work is a good refresher on the parts. If you plan to add storage, see our hub on batteries and export.

Sources

Common questions

How do I know if my solar panels are working?

Open your app on a bright day and check that generation rises around midday and falls in the evening. A flat line, or a number far below the same time last week, is worth a call to your installer.

What is the difference between generation and export?

Generation is all the power your panels make. Export is the part you do not use or store, which goes to the grid. You use the rest at home.

Why is my solar output lower than my installer's estimate?

Weather, season and shade all change output. The MCS standard treats the performance estimate as guidance for the first year only. Compare a full year, not a single week.

Will my inverter warn me if something fails?

Some do. Energy Saving Trust says certain inverters have online monitoring and can email you if the system fails. Ask your installer whether yours does, and check that alerts are switched on.

Does the app show what I earn from the grid?

Not always. Many apps show export in kilowatt hours but not the payment. Your payment comes from your Smart Export Guarantee supplier, so check that bill or app.