BESS storage

Stationary battery storage (BESS) in a public pool is currently not economical at sites without redispatch stress and with a low day-ahead spread. Typical site: redispatch score 0/10 (no curtailment), grid-control score 7/10 (little curtailment leverage). Day-ahead spread ~150 €/MWh — too little for BESS arbitrage. Re-evaluate in 2028/29 if the spread exceeds 200 €/MWh or a grant co-funds storage. For now, load management (synchronising HP/ventilation/filters to PV) with a payback below 1 year is the far better investment.

Basis: Practice + site analysis

VDE-AR-N 4105 governs the connection of generation systems to the low-voltage grid. Systems above 30 kVA must participate in the grid-operator control scheme — the operator may curtail feed-in when the grid is critically loaded. A pool with 643 kWp is well above this threshold. The local low-voltage cluster score is 7/10, so the probability of curtailment is low but technically possible. Load management lowers this risk because less power is fed in.

Basis: VDE-AR-N 4105

The ISEK programme co-funds municipal climate-protection and refurbishment measures at 50 %, capped at 500,000 € per measure and 5 M€ per project. Precondition: the measure is anchored in the municipal climate-protection plan. Processing takes 6-12 months. Measures can be bundled (e.g. heat pump + insulation + load management in one application) but cannot be combined with federal BAFA funding on the same asset. Note: PV car-port roofing is usually funded separately at 30 %; ISEK eligibility for PV is a case-by-case decision requiring a climate-protection rationale.

Basis: ISEK (German regional urban-development grant)

Load-management systems switch shiftable loads in sync with PV production. In a pool the ideal moves are: modulate the heat pumps onto the PV profile, raise ventilation stages when PV surplus exists, run the main filter pumps during the day, dim lighting during daylight. Investment 30-60 k€ depending on the number of switching devices and building-management integration. Self-consumption ratio typically rises from 30 % to 55-70 % with broad integration. Precondition: all main loads are Modbus/MQTT-capable.

Basis: Practice (e3dc, ESL, Solarwatt)

Pools have a daytime load profile that fits PV well: pumps run during opening hours (typically 9 a.m.-9 p.m.), ventilation ramps up in day operation, heat-pump heat-up can be time-shifted. Without load management the self-consumption ratio is 30-40 %. With load management (all main loads controlled): 60-75 %. Adding BESS: 80-90 % is possible but only economic at high day-ahead spreads. Example potential: 643 kWp × 815 kWh/kWp/a = 524 MWh/a; at 60 % self-consumption = 314 MWh/a × (0.25 − 0.06) €/kWh = 60 k€/a of extra saving from load management.

Basis: Practice studies