Energy Harvesting Calculator Tool

Energy Harvesting Calculator Tool

Configure an IoT node, choose an energy source, size reserve storage, and decide whether the design can run without regular battery replacement.

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A beginner-first sizing calculator for energy-harvesting IoT systems with source presets, load duty-cycle calculations, storage reserve checks, and a synchronized 24-hour energy animation.
Animation Beginner First Calculator Energy Harvesting

Energy Harvesting Calculator Tool

Build a first-pass energy budget for a self-powered IoT node. The model compares harvested energy, load energy, and reserve storage so the learner can see why average power and outage reserve must both work.

2.13 mW average harvested power
0.86 mW average load power
+30.5 mWh/day daily energy balance
22.0 h storage-only reserve
TrySelect Indoor solar with Light density 0.08 mW/cm2, Panel area 24 cm2, Useful hours 10 h/day, and Harvest efficiency 16%.
ObserveDaily harvested must exceed Daily load for a surplus, while Required storage rises when Reserve target grows beyond 24 h without light.
ExplainAt 16% Harvest efficiency, Peak harvested multiplies source density and collection size; daily energy then multiplies useful hours and is compared with duty-weighted load.
Technical boundariesThe 24 h profile omits weather distributions, shading, converter quiescent loss, cold start, leakage, battery chemistry, charge limits, temperature, ageing, radio retries, and voltage-dependent capacity.
Colour keyenergy power identitycurrent / primaryreference / datasuccesscautionerror / failure

Goal

Find whether a harvesting source and reserve store can support the selected IoT workload.

Try First

Compare the room sensor preset with RF harvesting, then watch daily balance and reserve change.

Watch

The energy trace, storage tank, sizing equations, and design flags update together.

Why It Matters

A design can have enough average energy but still fail when the source is unavailable.

1. Source Estimate peak harvest from source strength, size, and efficiency.
2. Average Convert peak harvest into daily energy using useful hours.
3. Load Average active and sleep current over one hour.
4. Storage Check reserve energy for nights, outages, or quiet periods.
5. Verdict Classify the design using daily balance and reserve margin.

Controls

Start with a scenario, then adjust the harvester, load, and reserve target.

Scenario indoor room
Source indoor light
View 24 h trace
Playback manual
Estimated light level at the indoor panel.
Active harvesting area or source coupling scale.
Hours per day when the source is usefully available.
Combined source, converter, and power-management efficiency.
Regulated voltage used by the sensor node.
Current while sensing, processing, or transmitting.
Seconds active per hour. This controls load duty cycle.
Current while the node waits between events.
Reserve store supercapacitor
Usable energy uses a 3.3 V to 2.2 V voltage window.
Battery reserve assumes 80% usable energy for this first-pass model.
Expected period without useful harvested energy.
7.68 mW peak harvested power
1.3% active duty cycle
21.0 mWh usable storage energy
Sustainable design result

Day View

The 24-hour trace shows when harvested energy enters storage and when the load consumes energy.

Source estimate
Reading: The source has enough daily energy and reserve storage for the selected target.

Live Design Decision

Indoor solar can work when the panel has enough area, useful light hours, and a low-duty sensor load.

Harvest side
Source modelIndoor solar
Peak harvested7.68 mW
Daily harvested76.8 mWh/day
Required peak2.78 mW
Load and reserve
Average load0.86 mW
Daily load20.6 mWh/day
Reserve target24 h
Required storage20.6 mWh
Design flags

The selected design is practical under the classroom assumptions.

Harvest Equation

Ppeak = source x size x efficiency.

Pavg = 7.68 mW x 10/24 = 3.20 mW

Load Equation

Average current combines active and sleep current.

Iavg = 260 uA, Pload = 0.86 mW

Storage Sizing

Supercapacitor reserve uses the usable voltage window.

Cmin = 24.5 F for 24 h reserve
Beginner Ramp

Energy harvesting has two separate questions:

  • Daily balance: harvested energy over a day should exceed load energy.
  • Reserve: stored energy should run the node when the source is absent.
  • Duty cycle: short active bursts can still dominate average load.
Core Formulas

Average harvest: Pavg = Ppeak x useful hours / 24.

Average load: Iavg = Iactive x duty + Isleep x (1 - duty).

Supercap: E = 0.5 C (Vhigh^2 - Vlow^2).

Battery: Eusable = mAh x V x usable fraction.

Quick Reference
  • Use margin because source power varies with weather, placement, vibration, or RF exposure.
  • Reserve storage covers night, shutdowns, or quiet periods.
  • RF harvesting is usually only for very low-duty tags or sensors.
Source Notes

Solar depends on area and light. Vibration depends on coupling to the moving structure. Thermal depends strongly on sustained delta-T. RF depends on available field strength and rectifier losses.

Storage Notes

A supercapacitor can deliver many cycles but has limited energy. A rechargeable cell stores more energy but adds charge-management, cycle-life, and safety constraints.

Accuracy Notes

This is a teaching calculator, not a final hardware design. Real systems require measured source profiles, converter startup checks, leakage current, temperature derating, and worst-case load testing.

Practice 1

Select RF for the asset tag. Reduce active time until daily balance becomes positive.

Practice 2

Select bridge monitor and lower useful hours. Decide whether storage or source power fails first.

Practice 3

Switch to recharge cell storage and compare reserve hours with the supercapacitor result.

Related Study

Energy Harvesting Workbench

Explore source models and reserve warnings with a stage-based flow.

 Power Consumption Calculator

Refine active, sleep, and communication load assumptions.

 Battery Life Calculator

Compare harvested operation with primary battery operation.