How does Renovessa calculate solar payback?

It compares cumulative scenario cash flow with installed cost using monthly import/export modeling and disclosed escalation and degradation assumptions. If the balance never crosses zero, it says payback was not reached.

Are SREC proceeds included in utility savings?

No. Utility-bill savings and market-credit cash flow are separate lines with separate evidence and uncertainty.

Why must I confirm my electricity rate?

A utility candidate is not proof of your tariff. Confirmation prevents an unverified third-party lookup from silently determining a money result.

Cash-flow methodology

Solar savings and payback in the DMV

Payback is not production multiplied by today's retail rate. Renovessa models monthly imports and exports, keeps market credits separate, and withholds money results until the homeowner confirms the tariff inputs.

Editorial owner: Renovessa Research & ProductSubstantively reviewed September 2, 2026

Calculation-method review complete; future utility and market values remain scenarios.

From energy balance to bill estimate

For each month, production first offsets that month's modeled consumption. Remaining consumption is grid import; surplus production is grid export. Imports use the confirmed import rate, exports use the separately confirmed compensation assumption, and fixed charges remain in both baseline and solar cases.

What changes over the analysis period

The model discloses electricity-rate escalation, panel degradation, analysis horizon and any included recurring cash-flow items. It recalculates imports and exports as production changes rather than applying one inflated savings multiplier.

First-year utility-bill savings
Separate verified incentive or SREC cash flows
Installed cost under the selected ownership scenario
Cumulative cash flow and the first year it crosses zero
‘Not reached’ when cumulative cash flow stays negative

Payback is not a guarantee

Future rates, system performance, maintenance, market-credit prices and household usage are uncertain. A useful result is a scenario tied to saved inputs and versions, not a forecast presented with fake precision.

Frequently asked questions

How does Renovessa calculate solar payback?: It compares cumulative scenario cash flow with installed cost using monthly import/export modeling and disclosed escalation and degradation assumptions. If the balance never crosses zero, it says payback was not reached.
Are SREC proceeds included in utility savings?: No. Utility-bill savings and market-credit cash flow are separate lines with separate evidence and uncertainty.
Why must I confirm my electricity rate?: A utility candidate is not proof of your tariff. Confirmation prevents an unverified third-party lookup from silently determining a money result.

Sources, review and limitations

Renovessa uses primary government, regulator, utility and model-provider sources. Links below are the evidence pack for this guide; account rules, funding and eligibility still require confirmation at decision time.

NREL — PVWatts Calculator
Production-model reference. Renovessa records the model version used for each estimate.
Maryland Public Service Commission — net metering
State regulator overview; utility tariffs and current program rules still govern an individual account.
Virginia State Corporation Commission — net metering
Virginia regulator overview and governing resources.
Pepco — DC interconnection and net energy metering
Utility process page; a submitted project must follow the current tariff and interconnection documents.

Substantive change: Documented monthly import/export and cumulative-cash-flow rules.
Update policy: Review dates change only after the evidence or explanation is substantively checked—not automatically.

Educational planning information only. It is not a contractor proposal, engineering approval, utility determination, legal advice, tax advice or financial advice. Read the calculator methodology.