01 — THE MECHANISM
Two ways to fill one battery.
Sunlight is free but seasonal. Wholesale electricity is seasonal in the opposite direction — cheapest in the windy dark months when your roof produces least. A battery that can accept both is working every day of the year. Charge at or below €25/MWh; discharge above €120/MWh.
01 — THE MECHANISM
CAROSOLARO Grid reads tomorrow’s prices.
CAROSOLARO Grid reads tomorrow’s published prices at about 14:00, plans the day, and executes it. You are not asked to watch a market. The only thing you notice is the bill.
≤ €25/MWh
Battery charges — price at or below €25/MWh.
> €120/MWh
Battery discharges — evening peak above €120/MWh.
Holds
Between those bands the battery holds, reserved for the house and the car.
02 — A DAY ON THE GERMAN MARKET
Buy at minus twenty-one.
Use at one hundred and ninety-one.
This is the shape of a representative winter day on the German day-ahead market. Around midday, wind and solar push the price below zero — you are paid to consume. By seven in the evening the same electricity costs nearly €200 per megawatt-hour.
Example: 02:40, wholesale −€14/MWh; evening nearly €200/MWh.
Germany recorded 576 hours of negative prices in 2025, and 85% of the 2026 negative hours fell between 10:00 and 16:00. Average daily swing €130/MWh. Since 1 January 2026, stored electricity is no longer charged grid fees twice — which is precisely what makes this strategy worth doing. Feed-in 7.78 c/kWh under EEG 2026.
03 — THE STACK
Deliberately simple, and deliberately not a utility.
Your existing supplier bills you. No CAROSOLARO tariff of our own.
01
The pavilion generates
A full-black roof (7–20 kWp) at a 15-degree angle. No visible racking.
02
The cabinet stores and converts
A three-phase hybrid inverter and an LFP battery rack, both concealed inside a fire-rated cabinet integrated into a timber column. Nothing is mounted on your house.
03
The software decides
CAROSOLARO Grid uses price data and solar forecasts to plan charging and discharging.
04
Your existing supplier bills you
Connects to dynamic tariffs — Tibber, aWATTar, Octopus, Zonneplan. We are not a retailer.
Why not a tariff of our own.
Becoming an electricity retailer means a supply licence, balancing responsibility, hedging and regulatory capital in every single market. That is a different company. Since January 2025 German law has required every supplier to offer a dynamic tariff, so the market access we need already exists — and using it keeps this product simple enough to sell through an architect or a car dealer.
04 — WHEN THE GRID FAILS
Twenty per cent is never for sale.
A fifth of the battery is held back at all times and never traded. When the supply drops, the pavilion disconnects from the grid and keeps your essential circuits running — lights, refrigeration, internet, heating controls, and the car if you need to leave.
This is also why the arbitrage figures in our simulator are calculated on 80% of capacity rather than all of it. The reserve is real, so the numbers account for it.
8 kWh
Reserved at 40 kWh. About 14 hours of essential circuits.
16 kWh
Reserved at 80 kWh. Roughly a full day and night.
24 kWh
Reserved at 120 kWh. Two days of careful use.
Transfer < 20 ms — fast enough that clocks do not reset.
Install
One day, three people, one crane.
Screw piles the week before. Cabinet connected, app walkthrough.
05 — NEXT
Germany
€130/MWh · 576 neg. hours
France
€142/MWh
Netherlands
€118/MWh
Texas
€168/MWh
Spain
€88/MWh
Gulf
not quoted · no accessible market