Example Data Table
| Use case |
Hot side |
Cold side |
Seebeck |
Resistance |
Array |
Load |
| Small stove charger |
180 °C |
35 °C |
53 mV/K |
2.2 Ω |
4 series, 2 parallel |
5 Ω |
| Exhaust heat recovery |
250 °C |
55 °C |
48 mV/K |
2.8 Ω |
6 series, 2 parallel |
8 Ω |
| Sensor node supply |
90 °C |
25 °C |
42 mV/K |
3 Ω |
3 series, 1 parallel |
10 Ω |
| Lab test module |
120 °C |
30 °C |
50 mV/K |
2.5 Ω |
2 series, 1 parallel |
5 Ω |
Formula Used
The calculator uses a simplified electrical model for a thermoelectric generator array.
Raw temperature difference: ΔT = Th − Tc
Effective temperature difference: ΔTe = ΔT × temperature factor × (1 − contact loss)
Module open circuit voltage: Voc,module = S × ΔTe
Array open circuit voltage: Voc,array = Ns × Voc,module
Array internal resistance: Rint,array = (Ns × Rmodule) ÷ Np
Operating current: I = Voc,array ÷ (Rint,array + Rload + Rwire)
Load voltage: Vload = I × Rload
Load power: Pload = I² × Rload
Ideal maximum power: Pmax = Voc,array² ÷ (4 × Rint,array)
Available heat: Qavailable = Qinput × (1 − thermal loss) − heat leak
Estimated efficiency: η = usable output power ÷ Qavailable × 100
How to Use This Calculator
Enter the hot side and cold side temperatures first. Choose the correct temperature units.
Add the usable temperature factor if the full temperature gap is not across the module.
Enter the Seebeck coefficient and internal resistance from the module data sheet.
Set the number of modules in series and parallel strings.
Enter the load resistance and any wiring resistance.
Add heat input, thermal loss, heat leak, converter efficiency, and target voltage when available.
Press Calculate to view voltage, current, power, load matching, and efficiency results.
Use the CSV or PDF button to save the calculated output.
What This Calculator Measures
A thermoelectric generator turns a temperature difference into electrical power. The hot side and cold side create a voltage through the Seebeck effect. A larger temperature gap usually gives a higher open circuit voltage. Real modules also have internal resistance. That resistance limits current and causes power loss inside the device.
This calculator combines temperature, Seebeck coefficient, module resistance, module count, load resistance, wiring loss, and converter efficiency. It estimates open circuit voltage, operating current, load voltage, load power, matched load value, short circuit current, and usable power after conversion. It also checks efficiency when heat input is known.
Why Load Matching Matters
A TEG does not deliver maximum power at every load. Maximum electrical power occurs when the external load matches the internal resistance of the generator array. Too small a load draws heavy current. That drops voltage and increases internal heating. Too large a load keeps voltage high, but current becomes weak. In both cases, useful output falls.
Series modules raise voltage. Parallel modules lower array resistance and raise current capacity. The best layout depends on the load and the required output voltage.
Thermal Conditions And Losses
The electrical result depends strongly on the real temperature difference across the module. Heat sinks, contact plates, thermal grease, and mounting pressure change that difference. The hot source may be strong, but poor cooling can reduce performance. The calculator includes a temperature use factor and contact loss setting. These values help model practical systems.
Heat input is optional. When it is entered, the calculator compares electrical output with available heat. This gives an approximate conversion efficiency. The estimate is useful for planning. It should not replace measured test data from a final build.
Practical Use Cases
Use this tool when sizing small waste heat harvesters, stove chargers, sensor power supplies, and educational generator arrays. Enter conservative values when data sheets are uncertain. Compare several load values. Then check whether matched power, voltage, and current meet the target. Good designs keep the module within safe temperature limits. They also use strong heat flow and steady cooling. Record each trial with module count and load value. Repeated records make comparison easier and reveal weak cooling during early testing stages.
FAQs
What is a thermoelectric generator?
It is a solid state device that converts a heat difference into electricity. One side stays hot. The other side stays cool. The temperature gap creates voltage.
What does open circuit voltage mean?
Open circuit voltage is the voltage with no load connected. It is usually higher than the working voltage because no current is flowing through internal resistance.
Why is load resistance important?
Load resistance controls current. A matched load can draw the highest ideal power. A very low or very high load can reduce useful output.
How do series modules affect output?
Series modules add voltage. Four identical modules in series can produce about four times the voltage of one module at the same effective temperature difference.
How do parallel modules affect output?
Parallel modules reduce total internal resistance. This can increase current capacity and improve power delivery to lower resistance loads.
What is the usable temperature factor?
It represents the fraction of the measured temperature gap that actually appears across the generator. Contact plates, heat sinks, and mounting conditions affect it.
Can this calculator predict exact real output?
It gives a planning estimate. Real output depends on module quality, heat spreading, cooling, pressure, aging, and test conditions.
Why is efficiency often low?
Thermoelectric generators usually convert only a small part of heat flow into electricity. Good heat transfer and strong cooling can improve practical output.