Solar Self-Consumption Optimization: From 30% to 80% with Battery Storage and ioBroker Automation

Werner.Solutions develops individual self-consumption optimisation plans for Austrian households and businesses. Learn more about the EnergyOptimizer system at <a href="https://energie.werner.solutions">energie.werner.solutions</a>.

Most PV system owners in Austria are losing money every day - without realising it. The reason: grid electricity costs 25–30 cents per kilowatt-hour. The feed-in tariff for surplus PV electricity is only 7–10 cents. That's a ratio of 3:1 to 4:1. Every kilowatt-hour you consume yourself instead of exporting is three to four times more valuable.

A concrete example: an 8 kWp system in Austria produces around 7,000 kWh per year. Without optimisation, only 2,100 kWh (30%) are self-consumed - 4,900 kWh flow to the grid. With optimised self-consumption (80%), you use 5,600 kWh yourself and export only 1,400 kWh. Additional annual savings: nearly €1,200.

The simplest and cheapest lever: move time-controlled appliances to midday hours. PV systems in Austria produce the most electricity between 10 am and 4 pm. Washing machine, dishwasher, and dryer together consume 2–4 kWh per cycle. Running these appliances daily during PV peak hours saves 600–1,200 kWh per year from the grid.

A battery stores surplus PV electricity during the day and releases it in the evening and at night. This is the most impactful single lever: self-consumption rises from 30% to typically 60–80%, depending on storage size and consumption profile.

Correct sizing: as a rule of thumb, 1 kWh of storage per kWp of installed PV capacity. For an 8 kWp system: 8 kWh of storage. Larger batteries yield diminishing returns beyond a certain point.

ioBroker is an open-source automation platform that intelligently networks household devices. Combined with a smart meter and PV inverter, ioBroker reads in real time: current PV output, household consumption, battery state of charge, grid draw.

Based on this real-time data, ioBroker automatically starts: washing machine when PV surplus >1 kW; dishwasher when battery >80% charged; heat pump when the solar forecast looks good for the next 2 hours; EV charging when surplus >4 kW available. Result: self-consumption rates of 85–92% are realistically achievable.

The electric vehicle is an ideal PV self-consumption buffer: it has a large battery (50–100 kWh), is often at home during the day (home office, weekends), and charging can be flexibly shifted. PV surplus charging means the wallbox dynamically adjusts the charge current based on available PV surplus.

Prerequisites: a wallbox with dynamic power control (e.g. Fronius Wattpilot, go-e Charger, or KEBA connected to ioBroker). Cost: €500–1,500 for the wallbox plus electrician installation. Typical saving for an EV: €400–600/year from PV electricity instead of grid power. For more, see our article on <a href="/en/blog/awattar-vs-tibber-oesterreich-vergleich/">dynamic electricity tariffs in Austria</a>.

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