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PVopti – tool for calculation the self-consumption of buildings based on hourly values

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PVopti is a freeware Excel-based tool that quickly calculates self-consumption, according to hourly demand and production profile, for different design configurations of a PV system. It has been elaborated within the IEA EBC Annex 67 (Energy Flexible Buildings) by the Institute Energy in Building of the University of Applied Sciences of North-western Switzerland.

Currently, the reliable evaluation of self-consumption and the interaction between the buildings and the grid is becoming crucial for the design. Nevertheless, the calculation approaches widely used allow for monthly and yearly evaluations of the energy demand.


Coping this issue, PVopti is an effective support for retrieving hourly energy demand profiles and photovoltaic production, evaluating the interaction with the grid and the self-consumption rate starting from the annual consumptio


n of a building and hourly climate data of the location of interest.


In particular, the tool needs a set of inputs related to:

  • building features (heated/cooled area, building use),
  • HVAC features (components and associated efficiency)
  • photovoltaic system (yield, surface of the PV plant)
  • weather data (temperature and solar radiation)
  • monthly or yearly consumption for heating, cooling, ventilation and appliances and lighting,


According to the inputs, PVopti bases the extrapolation of hourly values on the Swiss standard load profiles. As result, PVopti evaluates the self-consumption ratio, the feed-in ratio also considering the presence of batteries for the energy storage, as well as the energy demand and production.


The comparison between actual measurements of single family houses and apartment buildings with the self-consumption calculated with PVopti shows very good agreement. The limited number of necessary input data, the user friendliness and the output reliability make PVopti a very effective tool for the early design phase.


The tool has been recently extended to allow for bespoke climate data. Thanks to this extension, the tool can be widely applied by inputting the weather data (solar radiation and external temperature) of the selected location.


PVopti has been released in in English, and a user manual in French, Italian and German is available.


You can find the tool and the related materials (manual, scientific background and detailed description) at the following link: