New
Solar Panel Calculator
Panel count, wattage & cost for your home or business. BD & global.
CostNest Calculator
Solar Savings Calculator
Calculate your monthly electricity savings from solar, estimated payback period, and full 25-year return on investment. Includes BPDB net metering, annual electricity price escalation, and panel degradation modelling. No account needed — numbers update as you type.
Last reviewed: May 2026. Projections are estimates based on entered values and standard degradation models. Actual generation varies with weather, shading, panel orientation, and maintenance.
📌 Solar Savings Quick Reference
BD Peak Sun Hours
4.5–5.5 hrs/day
System Efficiency
~80% (losses, wiring)
Panel Degradation
0.5% per year
Typical Payback BD
4–7 years
Step By Step
How to Use the Solar Savings Calculator
6 steps
- Enter your solar system size in kWp (kilowatt-peak). Typical residential systems in Bangladesh are 1–5 kWp.
- Enter your current grid electricity rate per kWh — BPDB residential average is approximately ৳8.5–10/kWh in 2025.
- Enter your total installation cost for payback period calculation.
- Set the annual electricity price increase — Bangladesh historical average is 5–10% per year.
- Toggle net metering on if you are enrolled in BPDB's net metering programme and set your export rate.
- Review monthly savings, cumulative payback year, and 25-year total ROI in the results panel.
Worked Example
Worked Example for Solar Savings Calculator
Use this sample to sanity-check your inputs and understand what the final result represents.
- 1System size: 3 kWp · Peak sun hours: 5.0 hrs/day
- 2Year 1 generation: 4,380 kWh · Grid rate: ৳8.5/kWh · Year 1 savings: ৳37,230
- 3System cost: ৳240,000 · Payback period: ≈ 6.4 years
- 425-Year Projection (10% price rise/yr): Year 10 savings: ≈ ৳88,000 · Year 25 savings: ≈ ৳320,000
- 5Total 25-yr savings: ≈ ৳1.6M · 25-year ROI: ≈ 567% · Net profit: ≈ ৳1.36M
Final Result
Quality status is marked as 'Excellent' since both DHU and Defect Rates are within top-tier AQL boundaries.
Methodology
Solar Savings Calculator Formula & Methodology
This section explains the calculation logic, assumptions, and source material used to make the result more trustworthy and easier to verify.
Annual Generation (year N) = System kWp × Peak sun hrs/day × 365 × 0.80 × (1 − 0.005)^(N−1). Grid rate (year N) = Base rate × (1 + price increase%)^N. Savings (year N) = Generation × Grid rate (year N). With net metering: = (70% × retail rate + 30% × export rate) × Generation. Payback = year when cumulative savings ≥ system cost. 25-year ROI = (Total savings − System cost) ÷ System cost × 100%.
Practical Guidance
Solar Planning Tips for Bangladesh
- 1Use a Conservative Peak Sun Hours Estimate for Planning: Monsoon season (June–September) significantly reduces solar generation in Bangladesh. Using the average annual figure of 4.5–5.0 peak sun hours gives a realistic savings projection — not the clear-sky peak you would see in January or February.
- 2Enable Net Metering if Your System Generates Excess Power: If your system generates more than you consume during daylight hours, net metering exports that excess to BPDB at a feed-in rate. Over-sizing your system without net metering wastes generation — under-sizing means drawing more from the grid.
- 3Factor in a 10% Annual Electricity Price Increase for Realistic ROI: Bangladesh electricity prices have risen 5–10% annually on average. Setting a 10% price escalation means your solar savings grow each year even without consuming more electricity — making the ROI significantly better in years 10–25.
- 4Choose Hybrid (Battery) Systems for Frequent Load-Shedding Areas: On-grid systems shut down during grid outages for safety reasons. If your area experiences frequent load-shedding, a hybrid system with battery backup provides uninterrupted power.
- 5Get at Least 3 Installer Quotes — Prices Vary by 20–30%: Chinese panels are cheapest; Tier 1 brands (Longi, JA, Canadian Solar) offer better long-term warranties. Always compare quotes on a per-kWp basis and verify the warranty terms.
- 6Account for Roof Space — Each kWp Needs About 7–8 m²: A standard 400W panel occupies roughly 2 m². Shade from water tanks, staircases, or neighbouring buildings will reduce output — model this conservatively.
Frequently Asked Questions
How much can I save per month with solar in Bangladesh?+
A 3 kWp solar system in Bangladesh generates approximately 450 kWh per month (based on 5 peak sun hours/day and 80% system efficiency). At BPDB's residential rate of ৳8.5/kWh, that is roughly ৳3,825/month saved. Over a year that is ৳45,900 — and grows each year as electricity prices increase.
What is the typical payback period for solar in Bangladesh?+
For a 3 kWp hybrid system costing ৳210,000–270,000, the payback period is typically 4–7 years depending on your electricity bill size, local BPDB tariff, and whether you have net metering enabled. After payback, electricity generation is essentially free for the remaining 18–20 years of panel life.
What is BPDB net metering and how does it affect savings?+
BPDB net metering allows approved solar customers to export excess electricity to the grid and receive credit against their bill. Typically 70% of your generation is self-consumed (saving at full retail rate) and 30% is exported at a lower feed-in rate. This calculator models both the self-consumption and export portions separately when net metering is enabled.
How fast do electricity prices rise in Bangladesh?+
BPDB has increased residential electricity tariffs multiple times in recent years. The historical average annual increase is approximately 5–10%. Enter your own projection in the 'Annual Price Increase' field — a higher rate produces better solar ROI because every year the savings grow relative to what you would have paid on grid power.
Does solar panel efficiency degrade over time?+
Yes. Most solar panels degrade at approximately 0.5% per year. After 25 years, a panel rated at 400W will produce about 88% of its original output. This calculator applies standard 0.5% annual degradation across all 25 years so the savings projection is realistic rather than optimistically flat.
What is a realistic peak sun hours figure for Bangladesh?+
Bangladesh receives approximately 4.5–5.5 peak sun hours per day on average, varying by region and season. Dhaka averages around 5.0 hours, coastal regions like Cox's Bazar get slightly more, and northern districts slightly less. A conservative estimate of 4.5–5.0 hours is recommended for financial planning purposes.