1. Check what the tariff measures
Separate energy in kWh, billed power in kW, network use, metering and taxes. Ask the DSO how the measurement interval, billing period and any minimum charges are defined. A CHF/kW charge is not automatically a tax, and rules can differ between products. Reducing a peak has financial value only if it actually reduces the billed basis.
2. Size power and energy separately
Analyse measurements from a representative period covering seasons, machine starts and EV charging. Inverter power limits instantaneous support; usable capacity and state of charge limit its duration. Simulate successive peaks, a partly charged battery and changes in production. Software cannot guarantee that a sufficient reserve will always be available.
Illustrative example: calculate gross savings
Assume billed demand falls from 450 kW to 250 kW under a hypothetical tariff of CHF 12/kW per month. The difference is 200 kW, or CHF 2 400 per month and CHF 28 800 for twelve identical months. Supplying 200 kW for thirty minutes requires 100 kWh at the output, before losses and reserves are accounted for. This is neither a universal Swiss tariff nor a guaranteed annual saving.
3. Compare costs and competing uses
Include equipment, connection, protective devices, software, subscriptions, maintenance, losses, finance and replacement. Solar energy used for charging has an opportunity cost: it could serve another load or be sold. Backup and tariff arbitrage can consume the reserve intended for peaks. Aggregator revenue depends on eligibility, contract and market conditions; do not count multiple revenues from capacity that is unavailable for those services.
4. Prepare installation and handover
Have location, structure, access, ventilation, noise, fire safety and electrical design assessed. A tenant business must clarify landlord approval and required permissions; a removable battery does not remove those requirements. Check the model’s warranties and maintenance responsibilities. Request handover tests and measurements that allow actual performance to be compared with the simulation.