Public methodology
How the electricity estimate works.
Calculated output is kept separate from retailer-provided rates and TechManPat editorial explanation. No plan receives a ranking boost for a commercial link.
Open the calculator →Data sources and freshness
Rates are supplied through source-independent adapters: Australian Government Energy Made Easy Product Reference Data for supported NEM states, Victorian official data, Synergy, Horizon Power, Northern Territory regulated tariffs and TechManPat's internally verified plan register. Every result states plan count, retailer count, source, refresh date and limitations.
Annual-cost model
The same deterministic engine is used for manual and CSV journeys. It models a full year in local half-hour intervals, then applies supply charges, import rates, controlled load, feed-in credits, credits, fees, demand charges and VPP amounts.
Manual load profile
A manual daily or annual total is distributed across a transparent Australian household shape: morning activity, daytime occupancy and evening peak. Major loads alter only the relevant periods. This is an estimate, not meter data.
Solar generation
When actual generation is unknown, the calculator uses an indicative Australian seasonal generation profile and the supplied system size. Known exports are used to reduce double-counting. Future modelling will add more postcode-specific solar yields.
Battery dispatch
Solar surplus charges the battery first. Discharge respects usable capacity, reserve, charge and discharge limits and round-trip efficiency. Cheap-period grid charging occurs only when selected, supported and the tariff spread is meaningful.
EV charging
Annual kilometres, vehicle efficiency, home-charging share and charger power determine energy. Current behaviour starts at arrival. Optimised behaviour chooses the cheapest eligible periods before departure only when the user agrees to schedule it.
VPP calculations
VPP programs are separate from electricity plans. Joining credits, guaranteed annual payments and expected event payments are shown separately. Expected income includes a battery opportunity-cost warning and is never described as guaranteed.
Promotions
First-year credits affect first-year cost only. Ongoing annual cost excludes one-off promotions. Conditional benefits are applied only when their eligibility rule is met.
Confidence
High confidence needs roughly a year of usable interval data and known equipment. Medium confidence uses several months or annual totals. Manual daily usage and generic profiles remain indicative or medium depending on completeness.
CSV privacy
The raw file is read by a browser Web Worker and never posted to TechManPat Compare, Supabase, analytics, error reporting or an AI service. Refreshing or closing the page discards it. Email verification records abuse-prevention metadata only.
Known limits
Postcode mapping can cross distribution boundaries and must be checked against a bill. Embedded networks are excluded. AER-market coverage uses the supported Energy Made Easy source; Victorian Stage 1 currently includes the official default-offer benchmark rather than every market offer. Retailer eligibility and prices can change.