System Monitoring and Optimisation

You cannot manage what you cannot see

Most domestic systems report one number: how much the array generated. It is the least useful of the numbers available.

What determines the value of a solar and storage system is self-consumption — the proportion of generation you use yourself instead of exporting. Two identical arrays on identical roofs can differ substantially in what they are worth, entirely because of when the households are in and what their equipment is set to do.

Measuring that requires consumption data as well as generation data, and most installations were never fitted with it.

Levels of monitoring

Inverter level is what almost everyone has. Total generation, current output, and a fault log. Enough to know the system is alive.

Consumption level adds current transformer clamps or a meter at the incoming supply. Now you can see import, export, self-consumption and the shape of your demand across the day. This is the single most valuable addition to an existing system and it is usually a straightforward job at the consumer unit.

String level distinguishes one part of the array from another. On an east-west split it tells you immediately if one face has a problem.

Panel level requires optimisers or microinverters and gives per-module output. It is the only arrangement that shows you a single failing panel among twenty without anyone going onto the roof.

Building a baseline

An output figure means nothing on its own. It means something when compared to what your roof should produce.

We model an expectation from your array size, orientation, pitch, and the shading measured at survey, then compare actual output against it month by month. Deviations have characteristic shapes:

• A flat-topped curve on bright days suggests the inverter is clipping, which may be by design or may mean the array and inverter are poorly matched.
• A late morning start points at shading from something to the east, or an optimiser reporting late.
• A repeatable afternoon notch is almost always a fixed obstruction — a chimney, a flue, a neighbouring gable.
• A slow annual decline beyond normal degradation points at soiling, a failing bypass diode, or falling insulation resistance.

Optimisation is about schedules

Once the data is there, most of the gains come from settings rather than hardware.

Battery charge windows should match the cheap hours of your current tariff, not the tariff you were on when the system was commissioned. Discharge limits should reserve enough capacity to cover the expensive evening period without emptying the battery by seven o’clock. Where a forecast-aware mode is available, the battery can hold back overnight charging when tomorrow looks bright, and fill up when it does not.

Then there is the order of priorities for surplus: house load, battery, EV, export — or some other sequence, depending on your export rate and how much you drive. There is no universally correct answer, which is precisely why it is worth setting deliberately.

Alerting

A fault that nobody notices costs more than a fault that gets fixed. We set alerting so that a zero-generation day, a repeated inverter fault, or a string dropping out reaches you by notification or email rather than waiting for you to open an app you check twice a year.