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Grid-storage with self-consumption -> charg. and disch. times


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Good morning,

In this section of the Help "Self consumption with storage", we find some valuable information regarding the sizing:


Now there are some additional constraints to this sizing:

- The battery charging should not be too quick: for Lead-acid batteries, a charge in 3 hours is the minimum reasonable for the lifetime of the battery. Li-Ion batteries support higher currents (up to 1 hour). This should be limited by the charger maximum power. The eventual excess power energy will be injected into the grid. If this is not desired, the maximum PV power [kWp] should be able to charge the battery in 3-5 hours minimum.
- The inverter maximum power should be sufficient for feeding the maximum power required by the user. Again, the maximum discharge current should not be excessive (C3, i.e. discharge in 3 hours, for lead-acid, around C1 for Li-ion). If these powers are exceeded, the battery capacity should be increased. This may be the case when the full consumption of the day is concentrated on a short time.

Therefore, we want to be able to adjust to "Max. charging power" and the "Max. discharging power" values, in the "Storage" dialog box of the system, in the "Self-consumption" tab, so that we get appropriate charging and discharging times. However, I find very tricky that, as we change these values, we have no indication of how the charging time is changing.

I mean, I know we have some charging and discharging time information in the previous tab "Storage pack", but they are fixed values and don't change as we adapt/play with the "Max. charging power" and "Max. discharging power" values. I think it would be very useful to have an indicator in each boxes ("Battery input charger" and "Inverter Battery to user's consumption") that gives the charging and discharging times and updates the value as we play with the before-mentioned parameters.

I don't think it should be too hard, since we already get the information as a warning message when we enter too high values (e.g. "The Charging max. power (10.0 kW) is too high. It corresponds to a battery charging rate of C1.2 (1.2 hours)" or "The discharging max. power (15.0 kW) is too high. It correspond to a battery discharging rate of C0.8 (0.8 hours)"). I just think it would be really helpful to have the information constantly.



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