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Solutions / Engineering guide
Electricity Bills: Inputs for a Wind Project Assessment
An electricity bill contains quantities and charging rules that should not be collapsed into one average price. Identify the meter, period and applicable documents, then separate the components needed to assess a possible wind contribution at that connection.
A change in imported kWh is not the whole bill calculation.
The actual supplier and network documents establish how the site is charged. This guide organises those inputs without quoting a tariff, recommending a contract or promising a bill reduction.
01 / Bill identity
Connect the bill to the electricity service.
Record the account or meter reference, supply point, billing dates and document revision or issue date.
Record the account or meter reference, supply point, billing dates and document revision or issue date. Protect private account details when sharing an enquiry. Identify whether a bill covers one building, several load groups or a connection affected by existing local generation.
Keep the invoice, meter export and applicable charge schedule together. Note estimated readings, corrections and equipment changes during the period. A utility-import quantity may differ from total site consumption, so the wind assessment must retain the actual measurement boundary.
02 / Energy components
Distinguish consumed, imported and credited energy.
Extract the kWh quantities with their labels and periods.
Extract the kWh quantities with their labels and periods. Identify whether the document reports imports, exports, net quantities or an accounting credit. Keep meter readings separate from settlement entries that may represent energy from another period.
SAM’s electricity-rate documentation distinguishes energy-rate structures and defined buy or sell treatment. It is modelling context, not the site’s applicable charge schedule. Do not assume exports receive the import price or that permission to connect establishes payment for surplus wind generation.
03 / Demand components
Obtain the billing-demand definition.
If demand charges apply, retain the billed quantity and whether it uses kW, kVA or another documented basis.
If demand charges apply, retain the billed quantity and whether it uses kW, kVA or another documented basis. Request the measurement window, relevant peak periods and any reference to previous periods or other defined conditions. A bill’s peak entry is not automatically the motor’s instantaneous maximum.
Wind generation during one hour does not prove a reduction at the interval that establishes billing demand. Use aligned generation and load records at the necessary resolution. Keep an assumed future reduction separate from an observed demand quantity and from the electrical capacity required by the load.
04 / Time and tiers
Map the published schedule to the data period.
Record the applicable energy and demand time windows, weekday or seasonal distinctions and tier definitions from the actual documents.
Record the applicable energy and demand time windows, weekday or seasonal distinctions and tier definitions from the actual documents. State the time zone and how meter intervals align with those windows. If the schedule changes, retain both its effective period and the modelled period.
A single blended price can hide which imports would change. Do not replace missing schedule details with another country’s typical tariff. This page supplies no actual price or time-of-use recommendation; the analyst needs the rules applicable to the named site.
05 / Other bill items
Identify what changes and what remains.
Keep fixed charges, minimum charges, credits and other applicable items as separate entries with their basis.
Keep fixed charges, minimum charges, credits and other applicable items as separate entries with their basis. Mark whether the comparison treats an item as unchanged, modelled or unresolved. SAM’s billing-results definitions illustrate that bill components can follow different calculation rules.
Do not divide the full invoice by kWh and assume every generated kWh avoids that amount. Some items may remain despite lower energy imports. Charges or credits related to the proposed generation require confirmation from the relevant service documents rather than a generic renewable-energy assumption.
06 / Reconciliation
Make the assessment traceable to an actual billing period.
First reconcile the supplied quantities and rules against the existing bill, retaining discrepancies.
First reconcile the supplied quantities and rules against the existing bill, retaining discrepancies. Then compare a clearly labelled wind case with the same load, dates and charging basis. Link the local-use calculation and any export assumptions to the relevant energy paths.
Send MARSTON the non-sensitive meter boundary, demand and energy records, project connection and missing information required for the wind-equipment review. A bill assessment remains separate from the complete project budget. No tariff entitlement, fixed saving or payback period is promised here.
Continue the review with Wind Power Self-Consumption & Self-Sufficiency Metrics.
Continue the review with Wind Power Export Limits & Zero-Export Requirements.
Continue the review with Wind Power vs Grid Extension for Remote Sites.
General background: NLR SAM: energy and demand rate definitions · NLR SAM: distinct electricity-bill result components. These references explain industry concepts; they are separate from the applicable MARSTON product and project documents.
Prepare the information for this review.
Use the checklist to organise the project information. Mark unavailable items and retain document references.
| Review item | Information to provide | Purpose |
|---|---|---|
| Bill and meter | Connection, dates, reading basis and private-data handling | Define the assessed account scope. |
| Energy entries | Imports, exports, consumption and credit periods | Separate physical and settled quantities. |
| Demand definition | Quantity basis, intervals and applicable period rules | Identify billable demand. |
| Charge schedule | Time windows, tiers, fixed items and effective version | Retain the actual calculation inputs. |
| Reconciliation record | Baseline bill, stated case and unresolved differences | Make the comparison checkable. |
Engineering questions.
Can the total bill divided by kWh value all wind generation?
It can be a summary ratio, but it does not identify which energy, demand and fixed items actually change.
Is billing demand always instantaneous peak kW?
Use the actual billed quantity and measurement rules. It may differ from a brief equipment peak.
Are imported kWh the same as all site consumption?
Existing generation or storage can change the import boundary. Identify the meter and equipment arrangement.
Does export receive the retail import price?
No universal treatment is assumed. Obtain the applicable export and settlement documents.
Can annual generation prove a demand-charge reduction?
No. The relevant time-window and billing-demand evidence need an aligned assessment.
What should the first assessment check?
Reconcile the actual billing period, quantities and applicable rules before modelling a change.
Technical enquiry
Bring your project information to the discussion.
An electricity bill contains quantities and charging rules that should not be collapsed into one average price. Share the available information and the equipment scope you want reviewed in a technical quotation.