Calculated from the average regional solar performance ratio 80% and the deterioration rate 0.5%/year.
The results are estimates for investment planning.
Cost of Solar Cells Calculator
The Cost of Solar Cells Calculator estimates a utility tariff estimate for your scenario from the quantities, rates, period, units and other assumptions requested on the page. Replace the example values with your own solar cells figures and recalculate after changing an assumption. Treat it as a planning estimate and independently verify the current rule or provider terms.
Fill in the size of the solar cell system, current electricity bill, and region to calculate the electricity output, savings per month/year, payback period, and return over 25 years.
Calculation results
Saves a month.
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Saves a year.
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Return on Investment
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Net profit 25 year
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Producing electricity per day.
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Produces electricity per year.
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Reduced CO₂ per year
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System Size-
Total system cost-
Region-
Peak Sun Hours-
Roof orientation (efficient)-
Power rate-
ROI over 25 years.-
Total maintenance costs 25 years-
Annual Return Table (25 Years)
Year
Power output (kWh)
Save (baht)
Accumulative savings (baht)
Net profit/loss (baht)
Formula used for calculation
Power output per day = System size (kW) × Peak Sun Hours × Performance Ratio (0.80) × Roof orientation multiplier
Power produced per month = Power produced per day × 30 days
Savings per month = min(power output per month × electricity rate, current monthly electricity bill)
Depreciation = 0.5% per year (year N produced = year 1 × (1 − 0.005 × (N−1)))
Payback period = Cumulative savings in the first year − Cumulative maintenance costs − System cost ≥ 0
ROI = (net profit 25 year ÷ system price) × 100%
CO₂ reduction = electricity production per year × 0.499 kg CO₂/kWh (EGAT Emission Factor value 2024)
Calculation example
Example: House in Bangkok, electricity charges 3,000 baht/month, system installed 5 kW, roof facing south
Power produced per day = 5 × 4.5 × 0.80 × 1.0 = 18.0 kWh/day
Power produced per month = 18.0 × 30 = 540 kWh/month
Return on investment approximately = ~5 years (after maintenance)
Check before using results
Summary before deciding
This calculation result is suitable for preliminary planning. Actual figures should be checked from documents or official sources before making important decisions.
The calculation is based on the information you enter on this page.
Special cases may require additional information.
It is recommended to record or compare the results with the related tools below.
Typical house electricity bill 2,000-4,000 baht/month usually installed system 3-5 kW while electricity bill 5,000+ baht/month recommended 5-10 kW depending on roof area and budget
How many years does a solar cell pay for itself?
On-grid systems in Thai homes usually pay back within 6-9 years, depending on the system size, current electricity bill, roof orientation and region. The system has a service life of 25 years or more.
How much does it cost to maintain a solar cell per year?
Normal maintenance costs are approximately 2,000-3,000 baht/year for panel cleaning, system checks and general cleaning. The inverter may need to change the year at 10-15
What's the best roof orientation for solar cells?
South facing roofs are the best in Thailand, followed by east-west (~85%) and north facing roofs are the worst (~70%).
How many Peak Sun Hours in Thailand?
The average 4.0-4.8 hours/day. Eastern region has the most (~4.8) South region has the least (~4.0) because of clouds more than in Bangkok and Central region average ~4.5 hours/day.
What is the electricity rate in Thailand?
Progressive Rate — The more you use, the more expensive it is per unit. MEA/PEA has a rate of 3 per period as announced by the Energy Regulatory Commission (EGC) plus the FT (Fuel Tariff) that changes every 4 month.
What is the FT value and how does it affect the power value?
FT (Fuel Adjustment Charge) is an adjustment based on fuel costs, adjusted every 4 months. If FT is positive, it means the electricity bill is more expensive. If it's negative it's cheaper. As a result, the monthly electricity bill can change by 5-15%.
How can we save on electricity?
Turn off non-user devices (standby consumes 5-10% of electricity bills), replace old bulbs with LEDs, set air conditioning to 25-26°C, wash once full, check insulation and seal refrigerator doors.
Important note: This tool is a preliminary calculation to help assess the value of solar cell installation. Actual results depend on weather conditions, roof slope, shade, panel brand and actual market price. Experts should be consulted before making a decision.
English calculator guide
How to use the Cost of Solar Cells Calculator
Use this page to test a specific solar cells scenario. Enter your own values in the calculator above, review the units beside each field, and recalculate after changing an assumption. The result updates the cost of solar cells estimate instead of relying on a generic example.
Build a baseline solar cells case with figures that match your situation.
Run a second solar cells case after changing the rate, period, quantity or other key assumption.
Record the difference between the two solar cells results and the input responsible for it.
Inputs for the solar cells estimate
For this solar cells calculation, check the quantities, rates, period, units and other assumptions requested on the page. The result is designed to show a utility tariff estimate for your scenario, not a guaranteed provider price or official decision.
How the solar cells result is calculated
The calculator applies the displayed usage bands, tariff assumptions and billing components to the consumption entered. Reusing the same solar cells inputs will produce the same estimate, which makes the page suitable for controlled scenario comparisons.
Checks for a solar cells decision
Confirm any current rate, threshold or provider rule that could change the final amount. For solar cells, Use the estimate to plan a household or service cost. Actual charges can differ because of provider tariffs, minimum fees, taxes, location and billing-period adjustments. Because this calculation can affect an important financial, legal or health decision, independently verify the inputs and current rules before relying on the result.
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Review formula structure, test cases, data sources, effective dates, and risk language accordingly.How to check our · There is no claim that an outside professional reviewed it. Unless the page directly states the name and qualifications. This content is therefore not individual advice.
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