Project design > Economic evaluation > Feed-in tariff and self-consumption

This section defines the pricing strategy of electricity sale. It is used to calculate financial income over project life and evaluate system profitability.

Fixed feed-in tariff

A now common procedure, especially in several European countries, is the purchase, by the grid utility, of the total energy produced. The feed-in tariff is set by a long-term contract (usually 20 years), at a level determined at the system commissioning time, and fixed for the whole contract period.

Therefore the first (and simplest) option in PVsyst is to define a single fixed feed-in tariff over a given contract period. It is also possible to define a connection annual tax, as well as a progressive annual tariff variation. Finally the selling tariff variation at the end of the contract period should be defined. As usually the contract period will correspond to the loan refund period, the annual balance after this period (even with lower tariff) will dramatically increase until the end of life of the system!

Hourly/seasonal peak/off-peak feed-in tariff

In some countries the tariff is dependent on the hour of the day, or even on the season. PVsyst allows to define "Peak" and "Off-peak" tariff levels, for specified hours of the day. These tariffs may be different in summer and winter (with specified months).

In this case the final tariffs after the preferential contract period are all decreased by a same factor.

Hourly/daily tariff defined in a CSV file

For more complex pricing strategy in which feed-in price changes during the year without specific rules, you can define prices hourly for the whole year in a CSV file. See this section for more details.

Self-consumption economy

This concept is defined here with a consumption tariff when the owner is able to use the produced energy for himself (economy on the electricity bill), and another tariff for selling the overproduction to the utility.

This calculation requires of course that the user's needs are specified, and computed during the simulation, and that these data are stored in hourly values.

These tariffs may also be modulated according to the day hour. The consumption tariff is likely to be increased during the next years; therefore an annual tariff evolution can be defined.

Daylight saving time (DST)

This information has to be provided only if Hourly feed-in tariff strategy is selected. All simulations in Pvsyst are based on the winter time of the geographical site. For countries using Daylight Saving Time (winter and summer time), user has to provide the dates of summer/winter time change in order the system knows if a simulated specific hour occurs during peak or off-peak hours.