Market-wide Half Hourly Settlement (MHHS) is scheduled to begin migration in October, according to Cornwall Insight, which published the detail on 22 July 20251. The same analysis places the start of migration in the final year of the Department for Energy Security and Net Zero's four-year smart meter installation framework1.
That framework sets minimum coverage levels: at least 74.5% of homes and 68.7% of businesses must have smart meters installed by the end of 20251. Cornwall Insight describes the need for smart meters as "imperative" given the continuing market focus on enabling flexibility and the approach of MHHS migration1.
"Market-wide Half Hourly Settlement (MHHS) scheduled to begin migration in October"
The analysis states that the rollout "has been fraught with challenges over the last 15 years", citing COVID-19, technical issues and consumer uptake1. No further detail on the migration timetable, the bodies responsible for delivery, or the consequences of missing the coverage thresholds appears in the source1.
Why it matters for households
Half hourly settlement changes how electricity use is measured and priced across the market. Under the current arrangements, suppliers settle much of their customers' consumption against profile estimates rather than actual half hourly readings. MHHS migration moves the market towards settling against metered consumption in each half hour1.
For a household, the practical link is the meter. Settlement at half hourly resolution depends on half hourly consumption data, which is what a smart meter records and communicates. The coverage thresholds in the DESNZ framework, 74.5% of homes and 68.7% of businesses by the end of 2025, indicate the level of metering the framework expects before that migration begins1.
What this means for a home's energy independence is not stated in the source. The source does not report whether MHHS changes bill amounts, whether it enables time-of-use pricing for households, or what happens to homes without a smart meter once migration starts. Those points have not been reported in the material available1.
What happens next
Migration is scheduled to begin in October1. The end of 2025 is the deadline for the minimum coverage levels of 74.5% of homes and 68.7% of businesses under the four-year installation framework1. No further dated steps are given in the source.
Sources1 cited
- The Trials and Tribulations of the Smart Meter Rollout - Cornwall Insight, cornwall-insight.com