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The cheapest battery in your home is the boiler
A 100-150L hot-water tank stores 4-8 kWh as heat — about the same capacity as a small home battery. A €50 smart relay on the existing tank pays itself back within the first heating season.
Floor heating is the most flexible heater in your house
Resistive floor heating is in most Estonian homes and most of it runs dumb. The slab is essentially a thermal battery; price-aware scheduling captures spot-price spreads while the room temperature barely moves.
Home batteries, two stacked revenue streams
A 10 kWh home battery earns ~€730/year from spot arbitrage alone. Stacked with aggregated frequency-reserve revenue (only available via a BSP), the same hardware can clear above 10% IRR.
When your solar panels lose you money
On a sunny April afternoon, a 10 kW rooftop array can produce 8 kWh and lose money in the same hour. Smart self-consumption + curtailment + battery routing is what makes solar pay in 2025 Estonia.
EV charging: plug in at six, leave at eight
A 50 kWh top-up costs about €15 at 02:00 or €45 at 18:00. Smart charging on OCPP-compatible wallboxes re-optimises every day against tomorrow’s spot prices, saving 50-70% on EV charging.
Heat pumps run on dumb thermostats
A heat pump is the largest steady electrical load in winter, paired with a thermal mass that doubles as a battery. Price-aware scheduling captures spreads of 5-10x between cheap night hours and expensive mornings.
mFRR — where Estonian battery profits come from
Manual Frequency Restoration Reserve is activated by a human operator, with full delivery in 12.5 minutes. In Estonia, it is currently the most lucrative balancing market for batteries.
aFRR, the reserve in the middle
Automatic Frequency Restoration Reserve activates in ~30 seconds via TSO control signal, follows it on a 4-second cycle, and pulls the grid back to 50 Hz. PICASSO is quietly transforming the market.
FCR: what catches the grid when a reactor trips
Frequency Containment Reserve activates within 30 seconds of a frequency deviation, fully automatic, no TSO signal. Batteries dominate it. It is what made grid-scale storage economically viable.
PPAs — how long-term contracts financed the renewable boom
Power Purchase Agreements are 5–15 year bilateral contracts between renewable generators and corporate offtakers. They probably did more for Europe’s energy transition than any subsidy.
Power futures: how a wind farm gets its loan approved
Forward contracts on electricity, traded on Nasdaq Commodities and EEX, let buyers fix a price for delivery months or years ahead. Most settle financially against the day-ahead spot.
Intraday market — after the auction, reality drifts
After the noon auction closes, intraday opens — a continuous order book that runs until close to delivery. It is where flexibility actually pays.