Energy Harvesting Calculator

Energy Harvesting Calculator

Size an energy-harvesting IoT node by balancing harvested power, load power, storage energy, and outage autonomy.

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A beginner-first energy harvesting workbench with solar, vibration, thermal, and RF source models, synchronized energy-flow animation, storage sizing, daily balance, and practical design warnings.
Animation Beginner First Energy Harvesting Power Budget

Energy Harvesting Calculator

Balance ambient energy, converter losses, storage capacity, and node duty cycle. The goal is not only positive average power, but enough stored energy to survive cloudy, quiet, cool, or RF-poor periods.

3.15 mW average harvested power
1.01 mW average load power
+51.4 mWh/day daily energy balance
8.3 h storage-only autonomy
Setup

Choose the existing balance lens or the finite-store capacity lens.

Try

Load Finite 10 mJ, then change only Harvest scale from 1.00 to 1.50.

Observe

At Harvest scale 1.50, Spill fraction rises once the 10 mJ Finite-store capacity is full, while Served power stays on its demand plateau.

Explain

Within 8 slots, arrival-before-service can overflow a 10 mJ store even when later demand is unmet; mean energy alone loses that timing and headroom constraint.

Controls

Select a source, then tune the environment, node load, and storage reserve.

Source outdoor light
View energy flow
Playback manual
Outdoor light level on the panel during useful sun hours.
Active harvesting area or equivalent coupling scale.
Hours per day when the source is available.
Source and converter efficiency used by the classroom model.
Regulated voltage used by the sensor node.
Current while sensing, transmitting, or processing.
Seconds active per hour. This controls the duty cycle.
Current while the node waits between measurements.
Usable storage is calculated from the high and low voltage window.
Expected period without useful harvested energy.
1. Source Estimate how much ambient energy reaches the harvester.
2. Converter Apply realistic conversion and power-management losses.
3. Storage Store enough energy for periods with little or no harvesting.
4. Load Calculate average sensor-node power from duty cycle.
5. Decision Check daily surplus and reserve before calling the design sustainable.
75.6 mW harvested peak power
2.0% node active duty cycle
8.4 mWh usable storage energy
Sustainable design result

Energy Flow

The moving token follows energy from the ambient source through conversion, storage, and the node load.

Converter loss
Energy harvesting flow and storage model Interactive energy harvesting model with source, converter, storage, load, and daily energy balance.
Reading: Harvested peak power only happens while the source is available. Average harvested power is lower.

Live Design Decision

Outdoor solar can support periodic sensing if panel area, sun hours, and storage reserve match the load.

Harvest side

Source modelSolar panel
Peak harvested75.6 mW
Average harvested15.8 mW
Daily harvested378 mWh/day

Load and storage

Average load1.01 mW
Daily load24.3 mWh/day
Storage energy8.4 mWh
Reserve target8 h

Design flags

The average energy balance is positive and storage covers the selected outage target.

Harvest Equation

Peak source power is reduced by efficiency and availability.

Pavg = Ppeak x hours/24

Load Equation

Average current combines active and sleep current using duty cycle.

Pload = V x Iavg

Storage Check

Supercapacitor energy depends on the usable voltage window.

E = 0.5 C (Vhi^2 - Vlo^2)
Beginner Ramp

Energy harvesting is a balance problem: source energy in, converter losses, storage reserve, and load energy out.

  • Power is the rate of energy flow.
  • Energy is power accumulated over time.
  • Autonomy is how long storage can run the node without harvesting.
Core Formulas

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

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

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

Quick Reference
  • Positive daily balance means the average system can recharge.
  • Storage reserve handles night, still machines, low temperature gradient, or poor RF exposure.
  • RF harvesting usually supports only very low duty-cycle tags or sensors.
Solar Note

Solar design must use realistic useful sun hours, orientation, dirt, shade, aging, and seasonal variation. Outdoor peak values should not be treated as all-day values.

Thermal Note

Thermal generators need a sustained temperature difference and a heat path. If both sides warm together, the usable delta-T collapses.

Storage Note

Supercapacitors have leakage, voltage limits, and converter start-up constraints. The classroom calculation shows first-order usable energy, not a full hardware qualification.

Practice 1

Select RF and keep the default load. Explain why the daily balance becomes difficult.

Practice 2

Select Solar, reduce availability to 2 h/day, and increase outage target. Decide whether storage or load duty cycle should change first.

Practice 3

Select Thermal and vary delta-T. Notice that a small temperature difference gives much less usable power.

Related Study
Energy Harvesting Calculator Tool Use the detailed companion calculator for additional configuration. Power Consumption Calculator Refine active, sleep, and transmit load assumptions. Battery Life Calculator Compare harvested operation with primary battery operation.