Calculator inputs
Use the fields below to estimate hotel solar output, bill reduction, payback, room-night savings, and long-term value.
Example data table
This sample shows a mid-sized hotel using rooftop solar to reduce electricity costs and improve sustainability performance.
| Example metric | Sample value | Explanation |
|---|---|---|
| Monthly electricity use | 45,000 kWh | Total monthly consumption for guestrooms, HVAC, kitchen, laundry, and common areas. |
| Solar system size | 120 kW | Installed rooftop solar capacity for the hotel property. |
| Annual solar generation | 192,720 kWh | Estimated first-year output before annual degradation effects. |
| Self-consumption ratio | 78% | Portion of solar energy used on-site during hotel operations. |
| Year 1 net savings | $28,708.08 | Annual bill reduction after subtracting estimated maintenance cost. |
| Simple payback | 3.41 years | Approximate recovery period based on first-year net savings. |
Formula used
Annual generation = Solar size × Sun hours × 365 × Performance ratio × Seasonal factor
Self-used solar = Minimum of monthly generation, monthly generation × self-consumption ratio, and daytime hotel load
Bill savings = (Self-used solar × Grid tariff) + (Exported solar × Export tariff) + Demand charge savings
Maintenance cost = Net installed cost × Maintenance percentage
Year 1 net savings = Annual gross savings − Annual maintenance cost
Simple payback = Net installed cost ÷ Year 1 net savings
ROI = ((Total net savings − Net installed cost) ÷ Net installed cost) × 100
The model escalates energy tariffs annually and reduces solar production each year using the degradation rate.
How to use this calculator
- Enter the hotel’s average monthly electricity consumption.
- Set the current grid tariff and expected export tariff.
- Add the planned solar system size and average daily sun hours.
- Adjust performance ratio and seasonal factor for realistic output.
- Estimate self-consumption and daytime load share based on operations.
- Include demand charge savings, installation cost, and incentives.
- Set maintenance, tariff escalation, degradation, and analysis years.
- Enter rooms and occupancy to measure savings per occupied room-night.
- Press Calculate Savings to view results above the form.
- Use the CSV and PDF buttons to export the results.
FAQs
1) Why is self-consumption important for hotels?
Hotels usually save more when solar energy is used on-site instead of exported. Self-consumed electricity offsets higher retail tariffs, while exported power often earns a lower credit rate.
2) What does performance ratio mean?
Performance ratio reflects real-world solar losses from temperature, wiring, inverter efficiency, dust, shading, and system mismatch. It helps convert theoretical output into a more practical estimate.
3) How should a hotel estimate daytime load share?
Review interval meter data, HVAC schedules, kitchen activity, laundry runs, and occupancy trends. Hotels with strong daytime operations usually achieve higher direct solar utilization.
4) Does this tool include battery storage?
No. This version focuses on solar savings only. Storage can improve self-consumption and peak shaving, but battery economics require separate charging, degradation, and dispatch assumptions.
5) Why does tariff escalation matter?
When utility prices rise over time, each solar kilowatt-hour displaced becomes more valuable. Tariff escalation can significantly improve long-term cash flow and shorten effective payback.
6) What does degradation do in the model?
Solar panels slowly lose output over time. Degradation reduces annual generation each year, helping the calculator produce more realistic long-term savings estimates.
7) How is savings per occupied room-night useful?
This metric translates energy savings into hospitality language. It helps operators compare solar value against occupancy performance, room pricing, and property-level operating efficiency.
8) Are these results suitable for final investment approval?
They are useful for screening and planning, not final engineering approval. A detailed solar proposal should confirm load profiles, roof constraints, utility rules, and local incentives.