Explore how changing solar panels, battery storage, hourly appliance use and discharge power limits affects unmet electricity needs through a modeled winter period. Unlike a simple daily-energy sizing rule, this tool tracks the battery from one hour to the next.
Educational planning estimate, not a forecast or a survival guarantee. Sunlight patterns here are synthetic, not actual observations for your location. An apparently adequate hourly model does not certify inverter startup, battery charging in freezing conditions, motor operation, code compliance or backup reliability.
Compare a cabin, van or always-on network system through three synthetic sunlight patterns. Everything runs in your browser. This is not site-specific weather or certified equipment operation.
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An hourly educational scenario only. Neither the absence of shortfalls nor a high coverage percentage establishes physical device operability or outage reliability.
Teal line: stored energy as percentage of nominal capacity.
Gold: PV energy at DC bus (Wh). Slate: requested device energy (Wh). Teal: served device energy (Wh). Accounting boundaries differ; use the numeric table for exact values.
| Day / hour | PV (Wh) | Requested | Served | Unmet | Battery SoC | Constraints |
|---|
Critical-energy coverage: . Equipment verification remains unverified (surge, actual time of use, winter cell temperature and hardware compatibility not proven).
Consider a hypothetical system with a 4,000 Wh nominal battery, a 25% minimum state of charge, 2,000 Wh initial stored energy, 80% charging and discharging efficiency, and a 500 W battery charging and discharge limit measured at the DC bus. A divisible, directly supplied DC load requests different amounts in four consecutive one-hour periods. PV energy is listed after the controller, so its values are ready to enter the DC-bus balance.
| Hour | PV to DC bus | User request | User served | Unmet | PV curtailed | Stored at end |
|---|---|---|---|---|---|---|
| 1 | 2,000 | 400 | 400 | 0 | 1,100 | 2,400 |
| 2 | 0 | 800 | 500 | 300 | 0 | 1,775 |
| 3 | 0 | 800 | 500 | 300 | 0 | 1,150 |
| 4 | 0 | 400 | 120 | 280 | 0 | 1,000 |
Result: the load receives 1,520 Wh, misses 880 Wh, and finishes with 1,000 Wh stored (the configured 25% reserve floor). It curtails 1,100 Wh of solar in the first hour. The first hour with unmet modeled demand is hour 2, when the 500 W discharge power ceiling limits service to 500 Wh even though more energy remains in storage. Hour 4 is limited by the minimum battery SoC.
Energy check: 2,000 Wh initial battery + 2,000 Wh PV = 1,520 Wh served + 1,100 Wh curtailed + 100 Wh charge loss + 280 Wh discharge loss + 1,000 Wh final battery = 4,000 Wh.
This is an independent, deliberately simple test fixture, not the entire preset weather scenario above. It checks conservation and the chronological battery state, and it makes the distinction between energy (Wh) and power (W) visible.
Each appliance keeps its validated daily delivered Wh from the Off-Grid System Builder. You can inspect and edit 24 allocation weights, the availability fractions, and critical versus noncritical priorities. Without your measured readings, the hourly usage distribution is assumed.
Solar generation follows a bundled, normalized synthetic daylight shape. The model separately accounts for declared controller efficiency, extra non-overlapping loss assumptions and controller bus-output limitations. It does not reuse the Builder's daily peak-sun-hours multiplier.
Stored battery energy evolves from hour to hour between nameplate capacity and its minimum SoC reserve. Charging and discharging losses are applied to energy crossing the battery boundary; limits are in DC-bus W. Unknown equipment limits are explicitly unverified.
Loads are served in deterministic critical-first order; an atomic hour-equivalent load is either fully served or not served, while a divisible load may receive only mathematical partial energy. Inverter idle is reserved once as a prerequisite for AC operation; inadequate energy for idle triggers modeled inverter shutdown, not a fictional partially running inverter.
Three illustrative options—clearer cold days, prolonged overcast, and two particularly poor-sun days—are offered at 3, 7 and 14 days. The 24-hour appliance pattern repeats daily and the synthetic seven-day solar pattern repeats in the 14-day exercise. These are not local historical irradiance, probability estimates, sunrise calculations, generator scheduling or a substitute for equipment manuals.
No. It means this particular synthetic hourly energy calculation served all requested Wh. Sub-hour load peaks, surge current, actual winter solar conditions, ambient-versus-cell temperature, snow, shading and real equipment interactions were not established.
Wh measures energy remaining, whereas watts limit the rate of delivery. A discharge-power cap, a known inverter rating conflict, converter limits, appliance priority or inverter shutdown may cause unmet demand while stored energy remains.
The transferred battery is the Builder's illustrative sized capacity, not confirmed hardware. The model takes its nominal Wh unchanged and uses the Builder's usable fraction only to derive the reserve floor. Verify actual equipment capacity, charge specifications and battery management behavior separately.
No. v1 has no city data, real-time forecast, historical weather record or geolocation. A separately sourced and validated location-based dataset would be a future feature. For now, use the outcomes only to explore relative sensitivity to assumptions.
Continue with the appliance-based Off-Grid System Builder, Battery Runtime Calculator, LiFePO4 battery bank sizing guide, or off-grid cabin blueprint. For installation risks, see our electrical safety disclaimer.
Model: winter-1.0.0 · Scenario source revision: illustrative-1 · Numerical method: one-hour DC-bus energy balances and explicit reserve/power limits. Testing and editorial methodology.