Load Profile Analysis

Answer: Load profile analysis examines how electricity demand changes over time and compares it with solar production, operating schedules and tariff periods. It can estimate onsite solar use, grid imports, exports and interval demand peaks. Results depend on the measurement boundary, time resolution and model assumptions; the analysis does not guarantee savings or determine battery capacity from annual totals alone.

What Is Load Profile Analysis?

A load profile is a time series describing electricity demand. Load profile analysis interprets that series to answer questions such as when the site imports most power, how much solar overlaps with demand and which intervals determine billed demand.

The laboratory’s REopt load-data guidance distinguishes interval measurements, utility-bill totals and simulated profiles. These are different evidence bases. Monthly energy can constrain a model’s total without measuring its timing.

This page covers analysis after data acquisition. Use consumption profile import for file validation, units, timestamp conventions and missing-data handling. Load analysis provides broader demand context.

How Load Profile Analysis Works

1. State the question and measurement boundary

Choose the result needed: solar overlap, import energy, export energy, a tariff-defined demand peak or an operating scenario. Identify whether the records measure total site load, grid exchange or a particular circuit.

Grid imports after solar installation can omit consumption served directly by PV. A battery or other generator introduces additional flows. Do not compare a production series with an import-only series and label the result whole-building self-consumption without reconstructing the load.

2. Align the time series

Match the dates, interval durations, time zone and start/end timestamp conventions of load and solar records. Handle daylight-saving transitions and missing periods explicitly. Convert interval-average power to energy where needed; do not treat instantaneous power samples as complete interval energy.

For example, 4 kW averaged across 15 minutes corresponds to 1 kWh. When comparing demand peaks, retain the tariff’s interval convention as well as the energy sum.

3. Describe the operating pattern

Separate operating days, closed days, seasons and unusual events. Inspect the chronological profile before creating average weekday or weekend curves. Record whether a low-load period represents a real closure, a missing record or a meter fault.

A typical-day chart is a summary, not the original chronology. It can hide the intervals that set demand charges, production shortfalls or storage needs.

4. Calculate solar overlap and grid exchange

For a simplified no-storage interval model with compatible energy quantities:

Direct solar[t] = min(PV energy[t], site load[t])
Export[t] = PV energy[t] − direct solar[t]
Import[t] = site load[t] − direct solar[t]

This interval-net approximation can hide switching within a coarse interval. Reconcile measured import and export records when available. Storage requires its own charging, discharge, loss and stored-energy ledger. The self-consumption calculation guide explains the two ratio denominators and those accounting limits.

5. Apply the actual tariff and compare scenarios

Keep energy charges, export credits, demand charges, minimum bills and fixed charges separate where applicable. SAM’s electricity-rate documentation illustrates why rate structures and compensation mechanisms need explicit modeling; its conventions are not universal rules for every utility.

Compare the bill without the proposed project with the bill under the proposed project. Use consistent load and weather assumptions. If a tariff changes after installation, identify that change rather than attributing all the difference to solar production.

6. Report limits and sensitivity

Retain the source data, transformations, production assumptions, tariff version and excluded features. Compare alternative load schedules or production cases when timing is estimated. Identify changes in occupancy or equipment that could make the historical profile less representative.

Common Load Profile Shapes

These are descriptive patterns, not guaranteed residential or commercial benchmarks. An office can close during sunny weekends; a restaurant can have evening peaks; a home can have substantial daytime demand. Measure the actual site rather than assigning a building category a fixed self-consumption percentage.

Array orientation, system size and flexible-load timing can be tested against the profile. An orientation change can also change total yield. Evaluate its project-specific effect rather than promising a standard improvement.

Key Metrics & Calculations

SAM’s bill-results documentation distinguishes a calculated demand peak from billing demand when lookback conditions apply. A maximum demand observed in a sample is not automatically the billed demand for the month.

Worked example: one hour at 15-minute resolution

The following quantities are hypothetical interval energy values. Assume no storage or other generation and constant modeled flow within each interval.

Average site demand is 20 kWh ÷ 1 hour = 20 kW. The highest quarter-hour site demand is 9 kWh ÷ 0.25 hour = 36 kW. The load factor for this hour is 20 ÷ 36 × 100 = 55.6%.

After the stated solar overlap, the highest quarter-hour grid import is 6 kWh ÷ 0.25 hour = 24 kW, occurring when there is no PV production. Solar has not eliminated this later peak.

Self-consumption is 10 ÷ 11 × 100 = 90.9%; self-sufficiency is 10 ÷ 20 × 100 = 50%. High self-consumption does not mean the site is independent of grid imports.

If the first two quarters are aggregated to a half-hour, their 12 kWh becomes 24 kW average demand, hiding the 36 kW quarter-hour peak. That is why an energy-preserving resampling method can still lose information needed for a demand calculation. This single hour does not establish a month’s demand-charge reduction.

Practical Guidance

Keep energy overlap separate from demand savings

A project can offset many kWh while leaving its controlling demand peak unchanged. Conversely, a relatively short peak may drive a charge even when its energy contribution is small. Evaluate the actual tariff measurement window, not just a visually large spike or annual energy offset.

Model storage rather than summing annual surplus

The sum of annual exports is energy that occurred across many different times. It is not a battery-capacity requirement. Storage evaluation needs usable capacity, charging and discharge power, losses, reserve settings, beginning and ending stored energy and dispatch constraints.

SAM’s behind-the-meter dispatch guidance separates operating strategies such as self-consumption and bill-oriented dispatch. These are model-specific options, not proof that any battery can capture every peak or surplus interval. Compare costs and outcomes for the actual project before recommending storage.

Use the output as a decision record

Show the production/load overlay, interval imports and exports, tariff-period summaries and unresolved assumptions. Avoid replacing the report with a single “optimal size” or accuracy percentage unsupported by the data.

For bill-credit inputs, use the net-metering savings guide. Solar professionals can evaluate the generation and financial workflow with a representative profile or request a demonstration to confirm the available inputs and reports. Imported data alone does not establish a guaranteed financial result.

Methodology and limitations

SurgePV publishes this glossary as a solar software provider. The example is an independent arithmetic illustration, not a measured customer outcome. The linked laboratory documentation informs load, rate and dispatch concepts; it does not verify SurgePV’s import integrations, universal tariff coverage or numerical accuracy. Reviewed September 30, 2026.

Frequently asked questions

What is load profile analysis in solar design?

It examines the amount and timing of site demand, then compares that demand with modeled or measured solar production and applicable tariff periods. The output can describe solar overlap, imports, exports and interval demand peaks, subject to the data and model boundaries.

How do I get load profile data for a solar customer?

Use customer-authorized utility records or correctly configured site monitoring where available. Identify whether the readings represent grid imports or total site load. If only bills or building templates are available, label the resulting timing as estimated rather than measured.

Why does load profile shape matter for solar savings?

Equal energy totals can occur at different times. Solar and demand timing determine physical onsite use and grid exchange; tariff periods and credit rules determine how those flows affect bills. More onsite use does not automatically establish greater overall project value.

Can load profile analysis justify battery storage?

It can inform storage evaluation, but a profile alone does not establish a positive return or usable battery capacity. Model charging and discharge power, usable energy, losses, reserves, dispatch, tariffs and costs, and compare the same project with and without storage.