How to read your inverter data to spot energy waste

Every home battery system comes with an app. Most homeowners open it occasionally to check that the solar is generating or that the battery is not empty. Few know which numbers to watch to spot whether the system is actually performing efficiently — or quietly losing money.

Here is a practical guide to reading your inverter data, focused on the numbers that matter most for battery homes on smart tariffs.

The four numbers that tell you most

1. Battery state of charge at 17:00–18:00

This is the single most informative data point for a battery home on a smart tariff.

Your battery should be close to full at the start of the evening peak — when grid rates are highest and your solar has dropped off. As a rule of thumb, if your battery is consistently below 60% at 17:00 on days with reasonable solar generation, something is consuming your stored energy before it can be used for evening demand.

Common causes:

• Daytime EV sessions from Intelligent Go discharging the battery
• Heat pump afternoon cycle consuming stored energy before sunset
• Battery discharging to export when the export rate does not justify it

What to do: Check the battery SoC chart for any day you saw a higher-than-expected evening grid import. Look for drops in SoC during the middle of the day that do not correspond to high household consumption.

2. Self-consumption ratio

Most inverter apps show a self-consumption percentage — the proportion of solar generation consumed directly in the home or via the battery, rather than exported. As rough rules of thumb, a high self-consumption ratio (above 80% in summer, above 70% in spring/autumn) often indicates a well-configured system.

A consistently low self-consumption ratio (below 60%) usually means one of:

• The battery is full when solar peaks and you are forced to export at a lower rate
• The battery is not sized appropriately for your generation and demand
• EV charging is happening from the grid during off-peak rather than from solar

What to do: Check whether the battery reaches 100% SoC before midday on sunny days. If so, solar is being exported when it could be stored — or you need a larger battery or more demand during the day.

3. Grid import timing

Your inverter app's import chart shows when you drew from the grid and how much. The pattern matters more than the total.

Efficient pattern: Grid imports concentrated in the overnight cheap window (00:30–05:30 for Go). Minimal imports during peak hours (16:00–21:00). Near-zero imports during solar hours on good generation days.

Warning signs:

• Significant imports between 16:00 and 21:00 despite the battery having been charged overnight — battery may have been drained during the day
• Imports at 22:00–00:30 (before the cheap window opens) suggesting the battery ran out before cheap electricity was available
• Large imports at unexpected times on days with daytime Intelligent Go sessions

What to do: On any day with higher peak-hour imports than expected, cross-reference with the battery SoC chart and your EV session history. If the battery SoC dropped significantly at 13:00–15:00, an EV session is the likely cause.

4. Battery cycle count and daily throughput

Most inverter apps show total energy throughput through the battery — sometimes as a lifetime figure, sometimes as daily stats. This tells you how hard the battery is working.

A 10kWh battery doing one full charge/discharge cycle per day is operating normally. A battery doing 1.5–2 cycles per day is cycling more than expected — often a sign that it is being drawn into EV loads during the day and then recharged from solar or grid before the evening.

If you divide a £5,000 installed battery by a 4,000-cycle life, each extra full cycle works out to roughly £1.25 of battery life consumed before efficiency losses or warranty nuance. Extra cycling from avoidable conflicts adds up over a 10-year warranty period.

What your app does not show you

The most important gap in all consumer inverter apps is cross-device context. Your inverter knows:

• What the battery did
• What solar generated
• What the grid supplied

It does not know:

• Whether a battery discharge at 13:30 was because of an Intelligent Go EV session
• Whether your heat pump running at 05:45 drew from the battery or the grid
• Whether the import at 22:15 was avoidable if the cheap window had been anticipated

This context — which device caused which load, and whether the grid or battery supplied it — requires data from multiple systems simultaneously. The inverter sees the effect; it cannot see the cause.

A practical monitoring routine

If you want to catch energy waste early, check these three things once a week:

1. Battery SoC at 17:00 on the two most recent sunny days. Should be above 60%. If it is consistently lower, check the midday SoC chart for unexplained drops.

2. Peak-hour imports for the past week (16:00–21:00 each day). If these are consistently high despite the battery charging overnight, the battery is not reaching the evening with enough charge.

3. Any days where the EV session log shows a daytime charge. Cross-reference those days with the battery SoC chart. If the battery dropped significantly during the session, you lost stored solar to the car.

These checks take five minutes a week and will surface most common problems within a month of monitoring.

If your monitoring is showing exactly these patterns — battery low in the evening, daytime SoC drops, higher peak imports than expected — read how 1app.energy addresses each of them automatically.