Use this solar thermal storage duration calculator to estimate usable support time for a solar thermal collector system. Enter project-specific assumptions to see the main estimate and supporting figures. The result is intended for early planning and scenario comparison; final design should use site measurements, equipment data, hourly demand, applicable incentives, and professional engineering or financial review.
The main result translates the entered assumptions into a screening estimate for useful heat production. Compare scenarios by changing one assumption at a time.
This planning estimate excludes detailed hourly simulation, site constraints, equipment-specific performance, financing, taxes, and regulations unless explicitly entered.
For 1,000 kWhth, 90% usable depth, 92% efficiency, and a 200 kWth load: 1,000 × 0.90 × 0.92 ÷ 200 = 4.14 hours.
The result is most sensitive to the energy, capacity, efficiency, load, or cost variables used directly in the displayed formula. Test realistic low and high cases.
Yes. Replace the default assumptions with values covering the same period and consistent energy and power units.
Only through the annual output, irradiation, sun-hour, efficiency, or yield input. It does not model hourly or monthly variation.
No. Keep electricity in kWh and kW, and useful heat in kWhth and kWth. Convert all inputs to a consistent basis first.
No. Use it for screening and comparisons, then verify the project with site, equipment, structural, interconnection, storage, and financial analysis as applicable.
| Item | Use |
|---|---|
| Energy | Use kWh for electricity or kWhth for useful heat. |
| Power | Use kW for electricity or kWth for useful heat. |
| Percentages | Enter percentages as displayed values, such as 80 for 80%. |