Consult about the Suggested battery capacity C rating

[Mguevara]

Good afternoon,´

My consult is about how to interpret the suggested capacity of the battery given by the PVsyst at the top-right corner of the components selection window. My Suggested battery capacity is 2000 A-h.

I know that the database of the batteries in the software rate the capacity at C10 , however, i got a calculation from another software made by a distributor of battery banks resulting of an equal value but telling me that the value is at C100 because the calculation for the battery uses an amount of energy that will be used by 7 days ( my autonomy is seven days) and that amount of hours is something like 168 h, therefore i had to buy a battery of 2000A-h at C100 because 100 hours is "closer" to 168 hours.

kind regards,

Miguel Guevara

[André Mermoud]

As you mentioned, the battery bank estimation in PVsyst is expressed as C10 value, as the "characteristic capacity" specifying the batteries in PVsyst is C10.

However these sizing results should only be interpreted as a rough estimation.

There is no absolute way of defining the size of a battery bank, as this depends mainly on the meteo variability, and the eventual unequal use of the electricity.

In PVsyst, the estimation is performed by:

- generating a synthetic daily data set from the Monthly meteo data.

- performing a quick (simplified) simulation during this full year.

- estimating the probability of "loss of load" (PLOL, user's disrupting time), and adjusting the battery bank according to your specification.

Now this process is mainly dependent on the worst days sequence in the meteo data, which is highly variable, and depends on the synthetic generation.

In a next version of PVsyst we will provide a tool for performing a large set of Synthetic generations and analyze the probability distribution.