A solar-home monitor needs a documented measurement boundary. Grid import and export alone do not show total household consumption when solar or a battery supplies part of the load. List the flows you need before a qualified installer chooses equipment and sensor positions.
Reconcile a battery-free example
At a consistent AC measurement boundary, with no battery and aligned periods:
household energy = solar production + grid import - grid export
For an illustrative day with 20 kWh production, 8 kWh import and 11 kWh export, household consumption is 17 kWh. Subtracting export from import gives -3 kWh of net grid exchange, not negative household consumption. The house still used electricity.
These numbers are an accounting example, not a measured home. Align timestamps, units, included equipment and measurement points before applying the equation. Do not combine a monthly inverter total with a differently dated utility period.
Add batteries without double-counting
For separately measured AC battery flows at the same boundary, the accounting becomes production plus import plus battery discharge, minus export and battery charge. Define whether “household consumption” excludes battery charging and where conversion losses sit.
DC-coupled systems and hybrid inverters may expose different measurements. Do not force the simple AC equation onto fields that already combine solar and battery output. Ask the installer or equipment provider to identify each field and the compatible monitoring arrangement.
Give the installer this flow map
| Required flow | Evidence to retain |
|---|---|
| Grid import and export | Bidirectional measurement point and sign convention |
| Solar production | AC or DC basis, inverter or sensor source and included losses |
| Battery charge/discharge | Separate directions and relationship to hybrid-inverter totals |
| Household total | Direct measurement or documented calculation |
| Selected circuit | Loads included and whether already counted in the total |
Emporia’s solar documentation explains that its CTs measure AC conductors and that the supported configuration matters. Its sign conventions and circuit settings are product-specific; another dashboard can label the same direction differently. Do not physically reposition sensors to resolve an unexplained negative number yourself.
Separate energy reduction from tariff value
Moving a flexible load into a sunny period can reduce grid purchases without reducing the appliance’s kWh. The bill effect depends on import charges, export credits and the applicable tariff. Do not claim every self-consumed solar kWh saves the full retail price when exporting that energy would also have earned a credit.
Start with the data already available from the utility and inverter. Add monitoring when a defined missing flow or named circuit would change a decision. A standalone production portal is not a substitute for household-consumption measurement unless it also has the required consumption data.
Keep panel work with qualified installation
Service conductors can remain energized with the main breaker off. Have a qualified professional assess the service, solar and battery topology, enclosure space and exact manufacturer instructions. Retain the commissioning diagram and channel labels after the covers are closed.
Use the data-export guide to check whether aligned import and export records can be retained. For one ordinary appliance, the installation-method purchase brief may lead to a simpler supported measurement.