Background: Residential electricity prices in Germany are as high as €0.35–0.40/kWh, while the feed-in tariff (for surplus solar power exported to the grid) is only about €0.08/kWh. Self-consumption is far more cost-effective than selling electricity to the grid.

User Profile: A family of four living in a detached house with an existing 8kWp rooftop PV system. During the day, both parents are at work, so household electricity consumption is low.

Pain Point: A large amount of surplus PV power generated during the day is sold to the grid at a low price, while electricity is purchased from the grid at a high price at night. The self-consumption rate is only about 35%.

Solution:

• Configuration: 10kWh LFP residential energy storage + 5kW hybrid inverter

• Strategy: During the day, PV power is prioritized for household loads, with excess stored in the battery. At night, the battery discharges to power the home.

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Results:

• Self-consumption rate increases from 35% to 75%

• Annual electricity savings of approximately €1,200

• Payback period of approximately 6–7 years