Power Station Runtime & Sizing Planner
My power plan
Equipment
Equipment library
Example watts — edit to match your equipment.
64 matching items · All presets use AC input initially.
Selected equipment
No equipment added.
Setup
Planning window
Leave equipment usage blank to use the full window. For a brief session, enter its duration in hours.
Your battery
Station output ratings (optional)
Watt ratings alone cannot establish equipment compatibility.
Use nominal stored energy. Already measured usable output energy is not supported by this model.
Assumptions
10% reserve · 85% AC efficiency · 10% extra capacity margin
Edit charge window and losses
These defaults are editable assumptions. Reserve defines the lower charge limit; no second depth-of-discharge reduction is applied.
Solar recharge
Panel yield, input limit and charging losses
Illustrative assumptions. Separate panel yield from losses between the input and battery.
Plan a complete portable power setup
Build the load list, size stored energy, check output demand and estimate solar replenishment in one plan.
Use the complete planner when one decision depends on several limits. A station needs enough stored energy for the schedule, enough output for equipment that overlaps, and a realistic way to replace the energy if the plan includes solar.
Find the first constraint to fix
Read the plan as four separate decisions. Correct a failed output or energy check before comparing products, then decide whether the recharge target fits the way the station will be used.
- Stored energy is short
- Reduce optional watt-hours, shorten the schedule or compare stations above the calculated nominal-capacity target.
- Continuous or startup output is short
- Reduce planned overlap or compare a station with the required output rating. Extra battery watt-hours do not correct an inverter limit.
- Solar replenishment is too slow
- Test a smaller charge window, improve the yield assumption only when justified, or add compatible panel power up to the station input ceiling.
Before keeping the plan
- Keep one location, schedule and charging method in each named plan.
- Measure the largest example-wattage loads first.
- Enter the station capacity, continuous output, surge output and solar-input limits.
- Save an essentials-only comparison before adding convenience loads.
Method, formulas and verification
Understand the calculation path, the strongest inputs and the limits to verify.
- Equipment schedule
Watts, hours, duty and overlap
- Station size
Capacity, continuous W and startup W
- Runtime
Available Wh divided by repeating demand
- Solar recharge
Energy restored through useful panel power
Trips, field work and short outages
Model the equipment that will share one portable station during a defined period. Typical plans include campsite lighting and refrigeration, laptops and network equipment for mobile work, cameras and chargers for field production, or selected household loads during a short outage. Make separate plans when the equipment, schedule or available charging changes.
Separate equipment that behaves differently
Create separate rows for two laptops with different input power, or for the same appliance used for different lengths of time. Quantity is useful only when identical units share watts, usage, duty cycle, output path and startup demand. Switch a row off to compare the same plan with and without that load.
Treat capacity, output and recharge as three decisions
Battery watt-hours answer how much energy can be stored. Continuous and startup watts answer whether the station can supply the load. Solar input and equivalent sun hours answer how quickly energy may be restored. Passing one check does not establish the other two, and connector or voltage compatibility still needs a product-specific check.
Scheduled equipment energy
Average W × quantity × usage hoursEach row may use the full planning window or its own shorter duration.
Capacity with planning margin
(Battery Wh ÷ usable fraction) × (1 + margin)Conversion losses and overhead are applied before reserve and retention.
Solar replenishment
Energy to add ÷ stored solar powerPanel yield, station input limit and charge efficiency constrain stored power.
What changes the result most?
Change one input at a time and keep the measurement or specification that supports it.
| Input | Effect on the answer | What to verify |
|---|---|---|
| Equipment hours or duty cycle | Changes scheduled energy and the required battery capacity. | Record a representative day instead of the longest possible use. |
| Simultaneous equipment | Changes continuous and startup output requirements. | Mark a row as separate only when the operating plan prevents overlap. |
| Reserve, retention and efficiency | Change usable energy and runtime without changing appliance watts. | Use the station manual or a measured end-to-end result. |
| Panel yield and solar-input limit | Change recharge time and may make extra panel watts ineffective. | Confirm site conditions and the station PV input range. |
Common terminology
- Power station
- portable battery, solar generator
- Equipment list
- load list, appliance list
- Startup output
- surge watts, peak watts
- Solar input limit
- PV input ceiling, charge-input limit
Common mistakes
- Treating one total as the answerCapacity, continuous output, startup output and recharge time are separate constraints.
- Mixing different days in one planKeep one schedule and one charging situation in each saved plan.
- Leaving every example wattage unchangedMeasure the loads that dominate energy or output before comparing products.
Start with the equipment you will actually use
Add equipment from the library or create a custom row. Every library wattage is an illustrative planning assumption, not a specification for your model. Replace it with measured input watts when you can. A charger label may describe its maximum output rather than the electricity your device continuously draws. For appliances that heat, cool or change speed, measure a representative operating period. Keep the original measurement and its conditions with your equipment records.
Give each appliance its own share of the day
In sizing and Planner views, the planning window is the total period you need to cover. Each row can inherit that window or use fewer hours. An appliance used briefly should not consume its running power for the entire trip in your plan. Enter fractions of an hour for short sessions. Mark comfort or convenience equipment Optional to compare the full plan with an essentials-only case. The model assumes the equipment is disconnected outside its row usage period. Standby consumption applies only inside that period. Station overhead, when entered, runs throughout the whole planning window.
Watts and watt-hours answer different questions
Watts describe instantaneous power; watt-hours describe energy accumulated over time. Battery capacity and inverter output are separate specifications. A capacity estimate helps with duration, while the output assessment compares demand with entered ratings. Neither establishes connector, voltage, frequency or equipment compatibility. When entering Ah, use the nominal battery voltage associated with that capacity, not the voltage printed next to an AC socket or USB port.
Make cycling and standby explicit
Duty cycle is the fraction of the selected operating time spent at running watts. The remaining time uses the entered off-cycle watts. Start with measured values where possible; no refrigerator cycling percentage is inferred just from its name. A row representing measured average watts should normally use a full duty cycle, so the average is not reduced a second time. Output demand assumes rows may overlap unless you explicitly mark equipment Runs separately. Use that setting only when your operating plan prevents it from running with every other row.
Keep startup assessment separate
Enter startup watts per item if known. For rows that may overlap, the tool considers the units within one row starting together while the other rows are already running, then takes the largest row-start event. A row marked Runs separately is checked on its own. Different rows are not assumed to start simultaneously. Missing AC startup values keep the startup result unknown. Even when entered watt ratings cover demand, duration of the surge, apparent power, voltage, frequency, individual ports and protection behaviour need their own equipment-specific check.
Keep a plan you can explain
Save named plans in this browser, compare a saved snapshot with your current inputs, or export a JSON project to keep a portable copy. Storage belongs to this browser and site origin; clearing browser data can remove it. Imports are checked for size, version and structure before they replace inputs. Copy and print include assumptions so results remain understandable later. Your equipment list and calculation values are not submitted to a calculation service. Public page explanations are independent of saved projects.
Complete planning examples
Three common plans checked across scheduled energy, output and solar replenishment.
One plan, three independent requirements
Each scenario keeps its equipment schedule, battery assumptions and solar inputs together. The engine calculates the capacity target, simultaneous AC demand and equivalent solar recharge time separately so one passing result cannot hide another constraint.
FULL WORKED CALCULATION
Remote workday
One 65 W laptop for 6 h, one 30 W monitor for 6 h and a 12 W router for the full 8 h planning window.
- 1Scheduled equipment energy
- 2Required capacity with margin
- 3Continuous AC output
- 4Repeating-load runtime
- 5Equivalent solar recharge
The capacity result covers the timed work schedule, while the runtime result treats the same load pattern as repeating continuously. The solar result answers a third question: how much equivalent full-sun energy is needed to restore the selected battery percentage window.
Measure the laptop at its representative workload, confirm whether the monitor and laptop overlap, and check the station’s continuous, startup and solar-input specifications.
CALCULATED EXAMPLE 1
Field production shift
A 90 W editing laptop for 5 h, two 18 W camera chargers for 3 h and a 12 W LED panel for 4 h.
- Equipment energy
- 606 Wh
- Capacity with margin
- 931.68 Wh
- Continuous AC output
- 138 W
- Solar recharge
- 3.56 sun h
Separate charger quantity from laptop power so changes to either input remain easy to audit.
CALCULATED EXAMPLE 2
Short outage essentials
A 12 W router for 10 h, two 9 W lamps for 5 h and a 35 W fan for 6 h.
- Equipment energy
- 420 Wh
- Capacity with margin
- 603.92 Wh
- Continuous AC output
- 65 W
- Solar recharge
- 3.57 sun h
This example keeps optional comfort loads visible instead of hiding them inside one total wattage.
CALCULATED EXAMPLE 3
Weekend camping setup
A 45 W compressor cooler for 12 h at 35% duty, two 9 W lights for 5 h and four phone charges at 15 W for 2 h.
- Equipment energy
- 422.4 Wh
- Capacity with margin
- 643.1 Wh
- Continuous AC output
- 123 W
- Solar recharge
- 4.44 sun h
The cooler is the sustained essential load; lighting and charging remain visible as adjustable rows.
More common calculations
Calculated by the same engine as the tool.
| Scenario | Entered plan | Calculated answer |
|---|---|---|
| CPAP overnight plan | A 40 W CPAP machine for 8 h, a 5 W phone charger for 2 h and one 4 W night light for 8 h. | Equipment energy: 362 Wh · Capacity with margin: 585.59 Wh · Continuous AC output: 49 W · Solar recharge: 3.89 sun h |
| RV overnight essentials | A 40 W diesel-heater electrical load for 10 h at 50% duty, a 20 W water pump for 1 h and 24 W of lights for 4 h. | Equipment energy: 326 Wh · Capacity with margin: 496.33 Wh · Continuous AC output: 84 W · Solar recharge: 3.17 sun h |
Calculated reference table
All rows use 85% AC efficiency, a 100–10% battery window, 100% retained capacity, a 10% sizing margin, 80% panel yield and 90% charging efficiency.
| Scenario | Inputs | Engine result |
|---|---|---|
| Internet backup | 12 W router + 10 W modem for 8 h; 500 Wh battery; 100 W solar | Capacity: 253.07 WhRuntime: 17.39 hSolar: 4.17 h |
| Portable office | 65 W laptop + 30 W monitor for 6 h; 1,000 Wh battery; 240 W solar | Capacity: 819.61 WhRuntime: 8.05 hSolar: 3.47 h |
| Cycling cooler | 45 W cooler at 35% duty for 12 h; 750 Wh battery; 200 W solar | Capacity: 305.41 WhRuntime: 32.42 hSolar: 3.13 h |
| Outage essentials | 120 W cycling refrigerator + 12 W router for 12 h; 1,000 Wh battery; 300 W solar | Capacity: 965.41 WhRuntime: 13.67 hSolar: 2.78 h |
These are illustrative planning inputs. Replace equipment watts, schedules, battery limits and solar assumptions with values for the actual situation.
Questions when building a complete power plan
Decide what belongs together, how to compare scenarios and what the result cannot select for you.
What should go in one complete power plan?
Include equipment that may use the same station under the same schedule and charging assumptions. Create another named plan for a different day, location, season or load priority so the comparison remains understandable.
What size portable power station do I need for an appliance list?
The answer needs three specifications: nominal battery capacity in watt-hours, continuous output in watts and startup output when equipment has a surge. The complete plan also shows how long the entered battery may run the load and how much solar energy is needed to restore it.
Can battery size, runtime and solar charging be calculated together?
Yes. The complete plan uses one equipment list and one set of battery assumptions, then keeps station sizing, repeating-load runtime and solar recharge as separate results so each constraint remains visible.
How do I compare essential and optional equipment?
Mark convenience loads as optional, then switch the result between all active equipment and essentials only. The comparison reports the capacity reduction and, when available, the runtime gained by removing optional loads.
Why can a battery have enough energy but still fail the plan?
Battery watt-hours describe stored energy. The inverter and ports must also supply the simultaneous running watts and any startup event. A larger battery label does not automatically provide a higher output rating.
How should I plan a refrigerator, router and lights during an outage?
Keep each load on its own row, enter the router as continuous, give lights their expected hours and use a measured refrigerator duty cycle or average input. Add refrigerator startup watts when known.
Does this planner size a diesel generator?
No. It models stored electrical energy, inverter output and solar replenishment for battery power stations. It does not calculate engine loading, fuel consumption, generator derating, maintenance or exhaust requirements.
Can this calculation certify medical or emergency backup?
No. It provides an equipment energy budget. Critical-power continuity, device suitability, transfer equipment, alarms, redundancy and installation requirements need an equipment-specific professional assessment.
Sources, assumptions and model limits
Technical references and what this simplified model leaves out.
Reviewed 6 September 2026. Sources support terminology and methodology, not the illustrative equipment presets or default efficiency values.
- US Department of Energy — Energy Efficiency in the Home
Background on appliance electricity use. Historical educational material, not a current equipment catalogue.
- Victron — Inverter technical specifications
Shows why efficiency, idle demand, temperature and surge duration are separate specifications. Its product values are not universal defaults.
- Jackery — Watt-hour and battery ratings
Reference for energy units and the nominal-voltage requirement when starting from amp-hours. No product recommendation.
- National Laboratory of the Rockies — PVWatts
Context for solar losses and uncertainty. This tool uses a simpler local energy-budget model; it does not call or reproduce PVWatts.
This complete-plan model does not simulate an hourly load schedule, simultaneous solar use, battery temperature or chemistry curves, charging taper, startup duration, apparent power or product compatibility. Treat each result as a planning requirement to verify against the actual station, equipment and charging system.