Calculator Inputs
Example Data Table
| Project Type | System Size (kW) | Self Consumption (%) | Grid Rate | Export Rate | Estimated Year 1 Net Savings |
|---|---|---|---|---|---|
| Site Office Compound | 20 | 75 | 0.16 | 0.06 | 5,268.00 |
| Warehouse Roof Array | 40 | 68 | 0.18 | 0.07 | 10,619.00 |
| Precast Yard Facility | 75 | 62 | 0.19 | 0.08 | 18,944.00 |
Formula Used
Year 1 Generation = System Size × Peak Sun Hours × 365 × Performance Ratio × (1 − Shading Loss)
Selected Year Generation = Year 1 Generation × (1 − Degradation)(Year − 1)
Self Used Energy = Selected Year Generation × Self Consumption
Exported Energy = Selected Year Generation − Self Used Energy
Escalated Rate = Starting Rate × (1 + Rate Escalation)(Year − 1)
Gross Savings = (Self Used Energy × Grid Rate) + (Exported Energy × Export Rate)
Net Annual Savings = Gross Savings − Annual Maintenance
Cumulative Savings = Sum of all yearly net savings up to the selected year
Simple Payback = Installed Project Cost ÷ First Year Net Savings
How to Use This Calculator
- Enter the solar system size planned for the construction project.
- Add average daily sun hours for the site location.
- Enter performance ratio and expected shading loss.
- Set self consumption based on how much energy stays on site.
- Add the grid electricity rate and export credit rate.
- Include annual maintenance, degradation, and rate escalation.
- Enter total installed cost and choose an analysis year.
- Press calculate to view annual savings, cumulative savings, payback, downloads, and the graph.
About This Calculator
This solar annual savings calculator helps construction teams estimate the financial value of a planned solar installation using practical site assumptions. It works well for warehouses, site compounds, fabrication yards, precast plants, and other facilities with daytime electrical demand. Instead of giving only one output, it breaks savings into generation, self used energy, exported energy, gross benefit, net annual savings, cumulative savings, carbon reduction, and simple payback.
Construction businesses often compare power costs across fixed offices, temporary facilities, and expansion phases. This tool supports that review by including system size, sun hours, performance ratio, shading loss, self consumption, export credit, maintenance, degradation, and utility rate escalation. That combination gives a more grounded estimate than a basic payback worksheet.
The selected analysis year is useful when decision makers want to test savings in year 1, year 5, year 10, or later. Yearly production gradually declines because of module degradation, while electricity rates can increase over time. The calculator combines both effects, helping project managers and owners understand how annual savings may evolve through the operating period.
The example table offers quick reference values, while the Plotly graph shows how yearly net savings and cumulative savings move across the chosen time horizon. The CSV and PDF downloads make it easier to pass summary results into internal reviews, proposal packs, budget files, and stakeholder discussions. For final procurement decisions, pair this estimate with local tariff rules, engineering design, incentive details, and contractor quotes.
FAQs
1. What does this calculator estimate?
It estimates solar electricity generation, self used energy, exported energy, gross savings, net annual savings, cumulative savings, simple payback, and carbon reduction for a construction related solar project.
2. Can construction companies use it for warehouses and site offices?
Yes. It suits warehouses, workshops, precast yards, storage facilities, portable site offices, and similar buildings where daytime electricity demand can absorb part of the generated solar power.
3. Why is self consumption important?
Self consumption usually produces stronger value than exported energy because avoided grid purchases often cost more than the export credit paid for excess electricity.
4. Why include annual degradation?
Solar modules slowly produce less energy over time. Adding degradation gives a more realistic view of future yearly output and long range savings.
5. Does the export credit rate affect the result a lot?
Yes. Projects with lower on site usage may send more electricity to the grid, so the export credit can meaningfully change the total annual savings figure.
6. Is the payback result exact?
No. It is a simple planning estimate based on the entered values. Taxes, incentives, financing, downtime, tariff structure, and future operating changes are not fully modeled.
7. Can I use this for phased construction projects?
Yes. Run the calculator more than once using different system sizes, self consumption levels, or costs for each stage, then compare the annual savings outcomes.
8. How should I choose the performance ratio?
Use a value that reflects realistic system losses from wiring, inverters, temperature, dirt, and conversion effects. Many early feasibility studies start around 75% to 85%.