SMA SUNNY HOME MANAGER 2.0 - Application Examples

20 Application Examples
SMA Solar Technology AG
Operating manual 135HM-20-BE-en-19
20 Application Examples
20.1 Forecast-based battery charging
20.1.1 Objective and Background Information
Objective of using battery storage-systems
The objective of using battery storage systems is to not feed excess PV energy that cannot currently be self-consumed
into the utility grid, but instead to store it temporarily in batteries. It is then available and can be used when the self-
generated PV energy is not sufficient, e.g. on a gloomy day, in the evening or at night.
The duration of use can be set to 24h or 48h.
System operators are less dependent on the electricity purchased from the utility grid and increase their self-sufficiency
quota.
Background information on forecast-based battery charging
Without forecast-based battery charging
• If the battery is perhaps already fully charged by noon and can no longer take in any excess PV energy.
This then leads to the fact that the PV feed-in power at the point of interconnection has to be "derated" if the
nominal PV system power exceeds the maximum feed-in power specified by the grid provider at the point of
interconnection (see Limitation of active power feed-in).
• this can result in faster calendar aging of the battery if the state of charge is at 100% frequently and over longer
periods of time.
The following features of the SunnyHomeManager play an essential role for the forecast-based battery
charging:
• PV yield forecast
By using a weather forecast based on Internet data and by specifically adapting this to the local conditions, the
SunnyHomeManager can accurately predict solar irradiation for a few hours to a few days (48h).
• Consumption forecast
The SunnyHomeManager creates an individual load profile on the consumption behavior of the system.
• PV curtailment forecast
From generation and consumption data the SunnyHomeManager identifies when the PV nominal system power
would exceed the specified feed-in power at the point of interconnection. Without forecast-based battery charging
this PV energy would have to be derated or would not be generated – and thus would get lost.
• Prioritization of loads
A preferred consideration of the battery charging ensures sufficient availability of energy e.g. in the evening and
night-time hours.
• Specifying a minimum load capacity of the battery
Since a purely forecast-based charging of the battery can lead to a lack of sufficient stored energy available
when required, a percentage value can be set for the forecast-based charging of the battery. The battery is
definitely charged up to this value before the SunnyHomeManager enables the forecast-controlled battery
charging.
Ideally
• all loads are controlled so as to avoid derating losses and to be able to cover the houshold's energy demand
exclusively with self-produced PV energy.
The result is that the battery
• always has sufficient PV energy stored to satisfy the current demand.
• still has capacities to absorb PV energy even at the midday peak.