Renewable Energy City is a simplified, deterministic learning experiment, not a real power-system design tool. Equipment ratings and prices are fictional. It does not use live weather or predict a specific location's generation.
What happens every five minutes?
At each fixed five-minute step, solar and wind supply a shared DC bus. A 95%-efficient converter supplies AC demand, limited to 4 kW. An equivalent battery bank can absorb surplus or cover a shortage up to its available stored energy and charge/discharge power limits. Any unserved demand is recorded, and generation that cannot be used or stored is curtailed.
Every solar array has a nominal 1 kW peak and costs 200 fictional credits. Every wind turbine has a nominal 1 kW peak and costs 450 credits. Each battery adds 4 kWh of internal capacity and 1 kW of charge/discharge power, costing 300 credits. Charge and discharge efficiencies are 95% each. Batteries are treated as one equivalent bank.
Power and energy are different
kW means power at an instant. kWh is power integrated over time. The engine uses a five-minute timestep (1/12 hour). A 1 kW load held for one five-minute interval requests 1/12 kWh of energy.
The energy ledger checks: generated energy + initial internal battery energy = delivered AC energy + curtailed energy + conversion and storage losses + final internal battery energy. Requested AC energy = served energy + unserved energy. Battery limits are enforced in every step.
Solar, wind and loads
The fictional solar profile rises as a sine wave from 06:00 to 18:00 and is zero outside daylight. Weather presets scale this curve. Wind follows a simplified cut-in/rated/cut-out power curve: zero below 3 m/s or from 25 m/s, increasing to its nominal rating at 12 m/s. These curves are demonstrations, not manufacturer or measured resource data.
The island starts at 06:00 with four mandatory homes, a school active between 08:00 and 16:00, and a pump scheduled for 12:00–14:00. The pump is an atomic 0.4 kW load: it is supplied only when the whole five-minute interval can be funded. Homes and school can be partially served. Priority and stable IDs determine dispatch order.
Starting energy and comparison fairness
First Lights starts with all batteries empty (0% charge), so storage must first capture real daylight generation before helping at night. Other challenges use a disclosed starting percentage. Installing more batteries there increases initial stored energy; check the reported starting kWh before interpreting comparisons. Results are controlled comparisons only if weather, loads, model, duration and starting-energy rules match.
What a plot position means
Construction plots organize your equipment visually. Moving a panel does not change irradiance, wind resource, wiring resistance, shade, or equipment performance. This is not a geographic grid, full AC power-flow model, or physical wiring simulator. It excludes inverter motor surges, battery aging, temperature, protection devices and real installation costs. Consult real specifications and qualified professionals before electrical work.
What gets saved?
The game runs locally in your browser with no account or built-in behavioral analytics. Design progress may be stored in your browser storage. An export or challenge link contains the design you choose to share; no claimed score is trusted on import. The website's hosting provider may still process ordinary access logs; read our privacy policy for site-level practices.
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