Glossary
Load profile
Also known as: Lastgang, Load profile, Lastprofil, Consumption profile
The Lastgang is the Swiss term for a site's time-resolved load profile, measured by default in 15-minute average values. It shows when how much power is drawn: base load, production peaks, weekend and seasonal patterns. For sizing a PV system, battery storage and charging infrastructure, the load profile analysis is the central data basis, because it determines self-consumption potential, storage size and the savings potential on the demand charge.
Where does the load-profile data come from?
Larger sites usually already have load-profile metering in place: Art. 8 of the Electricity Supply Ordinance (StromVV) obliges grid operators to use load-profile metering with remote reading for generation plants above 30 kVA and for larger end consumers, and Art. 8a prescribes smart metering systems with an interface through which end consumers can retrieve their 15-minute values. Metering rules and data format are set by the VSE Metering Code Switzerland. The data is available from the grid operator in the customer portal or on request as a CSV file; for project design, the last twelve months are sufficient.
Without a load profile, every sizing exercise remains an estimate. An annual consumption figure says nothing about whether the electricity is needed at night or at midday, and precisely that decides the value of a PV system.
What does the load profile show?
Three key figures determine the sizing. The base load is the power the site always draws, at night and at weekends too; it limits how much solar electricity is consumed directly without storage (self-consumption). The peak load is the highest 15-minute average of the billing period, the month or the year depending on the grid operator; it determines the demand charge and the potential for peak shaving. The daily and weekly profile shows whether the load runs with the sun, as at day-shift operations with 60 to 70 percent self-consumption, or against it, as in office buildings with 20 to 40 percent (analysis of realised Ampere Dynamic projects).
Added to this are the duration and frequency of the peaks: a peak of 100 kW over 45 minutes needs 75 kWh of storage, one over three hours six times as much. This figure decides whether storage or load shifting is the more economical measure.
How is the load profile used in project design?
The load-profile analysis is a fixed part of the preliminary study by Ampere Dynamic: the load profile is overlaid with the simulated PV yield in the 15-minute grid, and from this follow the system size, storage power and capacity, and the savings potential on the demand charge in CHF per year. Results in 4 to 6 weeks from receipt of the data. What the load profile means for the economics of an industrial system is shown in the article Photovoltaics for industry and manufacturing businesses.