The Digital Reality: SMETS1 & SMETS2
In the UK, smart meters are designed to be extremely accurate. They measure the flow of electricity in two directions, but they are programmed to ignore "exported" energy when calculating your standard daily bill.
The "Meter Creep" Myth
On very old analogue meters (with the spinning disk), solar can occasionally cause them to rotate backwards. This is considered electricity theft in the UK if not declared, and you must contact your supplier to upgrade to a digital meter if this happens.
Export vs. Import: How you lose money
If your 800W kit is generating 600W, but your house is only using 200W, the extra 400W flows out through your smart meter to the grid.
- Your smart meter: Sees the 400W export.
- Your bill: Stays the same as if you used 0W.
- Your energy provider: Gets 400W of free green energy to sell to your neighbor.
Solution: Real-time Monitoring
To get the best out of your system, you need to align your usage with your generation.
How to "Zero Out" Your Meter
- Smart Plugs: Schedule your dishwasher or washing machine for 11 AM - 2 PM.
- Immersion Controllers: Use a diverter to heat water when solar is peaking.
- Batteries: Store the surplus for the evening.
SEG (Smart Export Guarantee) for Plug-in Kits?
Currently, most UK energy suppliers require an MCS Certificate to pay you for exported energy (SEG). Since plug-in kits are DIY and not MCS-installed, you usually cannot get paid for exports. This makes self-consumption the only viable path to ROI.