Allocate Time-of-Use Electricity With Smart-Meter Exports

Separate time-of-use energy into rate windows before allocating any personal load. Export interval kWh, map each timestamp to the tariff’s peak category, and price it at that category’s rate. Keep fixed charges shared. Assign a resident-specific device only when there is reliable device or session evidence.

Gather the records before dividing money

Get the tariff from the utility, not a roommate’s recollection. Peak windows may change by season, weekday, holiday, or service plan. The OpenEI utility rate database is a useful research starting point, but the current utility tariff and bill remain controlling. Confirm whether timestamps mark the beginning or end of each interval.

A useful source file has a date, account or item identifier, and the unit being charged. Screenshots cropped so tightly that dates and headings disappear are hard to audit. Keep the original document and make a working copy for annotations. Agree on the rule before placing anyone’s name beside a dollar amount.

Calculate and document the settlement

Create columns for timestamp, interval kWh, rate window, rate, and cost. Sum shared household usage by window. For an individually tracked load, such as a charger session, subtract its measured intervals from shared usage and assign that cost to the agreed person. Avoid using monthly kWh times an average rate, because that erases the point of time-of-use pricing.

Demand charges, minimum bills, taxes, and credits need separate rows. A solar export credit should not be casually netted against one resident’s peak use. Publish the mapping rule before calculating names, and test one bill together. If the process costs more time than it saves, agree on a simpler prospective rule.

Write the result as a miniature reconciliation: source total, excluded items, allocated amount, formula, individual shares, and settlement date. This takes a few extra minutes, but it prevents the familiar argument where two people remember different versions of the same calculation.

Before collecting payment, have a roommate who did not build the worksheet check it from the source document. Their job is to confirm dates, units, signs, and whether a credit was entered as a credit. They are not voting on the agreed rule again. Mark uncertain inputs clearly and settle the uncontested portion first. If a provider later issues a correction, post the correction beside the original entry so the trail remains understandable. Avoid sending repeated tiny transfers while a claim or adjustment is pending. One dated true-up is easier to verify than a string of payments with vague notes. Finally, keep account passwords, medical details, and full financial identifiers out of the shared record. The household needs evidence for the charge, not unrestricted access to someone’s private account.

How HomeCo helps

Use HomeCo to create a dedicated expense or project for this issue. Attach the statement, receipt, photo, or export; name an owner; and add the review date. Keep the calculation in the description so everyone can reproduce it. Record corrections as new entries rather than silently editing the original amount.

A clean record is especially useful when the account, lease, or equipment belongs to one person but several people contribute. HomeCo can keep the household-facing total visible without requiring private account credentials. Before closing the item, add a short decision note stating the allocation rule and who confirmed it.

Frequently asked questions

Should we round each person’s share?

Keep full precision while calculating and round only final payments to cents. Assign any remainder explicitly so the ledger still equals the source document.

What if one roommate will not share the records?

Pay or reimburse only the undisputed amount, request the specific document in writing, and preserve the request. Lease terms and local law determine any stronger remedy.

When should we recalculate?

Recalculate when a corrected bill, refund, occupancy change, equipment change, or verified new reading alters an input. Do not reopen a settled period merely because someone prefers a different rule later.