Solar Panel Calculator

Solar Panel System Calculator

Estimate your home's solar panel needs, potential savings, and system costs with this calculator. Input your average electricity usage, local sun conditions, and financial parameters to get a personalized projection.

Your Solar System Estimate:

Required System Size:

Estimated Number of Panels:

Estimated Total System Cost:

Estimated Annual Generation (Year 1):

Estimated Annual Savings (Year 1):

Estimated Payback Period:

Estimated Total Savings Over System Lifespan:

function calculateSolarPanelNeeds() { var dailyKWhConsumption = parseFloat(document.getElementById('dailyKWhConsumption').value); var peakSunHours = parseFloat(document.getElementById('peakSunHours').value); var desiredCoverage = parseFloat(document.getElementById('desiredCoverage').value); var costPerKWh = parseFloat(document.getElementById('costPerKWh').value); var costPerWatt = parseFloat(document.getElementById('costPerWatt').value); var panelWattage = parseFloat(document.getElementById('panelWattage').value); var degradationRate = parseFloat(document.getElementById('degradationRate').value); var electricityInflation = parseFloat(document.getElementById('electricityInflation').value); var systemLifespan = parseInt(document.getElementById('systemLifespan').value); // Input validation if (isNaN(dailyKWhConsumption) || dailyKWhConsumption <= 0 || isNaN(peakSunHours) || peakSunHours <= 0 || isNaN(desiredCoverage) || desiredCoverage 100 || isNaN(costPerKWh) || costPerKWh < 0 || isNaN(costPerWatt) || costPerWatt < 0 || isNaN(panelWattage) || panelWattage <= 0 || isNaN(degradationRate) || degradationRate < 0 || isNaN(electricityInflation) || electricityInflation < 0 || isNaN(systemLifespan) || systemLifespan 0) { for (var i = 0; i = totalSystemCost) { paybackYears = i + 1; } currentAnnualGeneration *= (1 – degradationRate / 100); currentCostPerKWh *= (1 + electricityInflation / 100); } } if (paybackYears === "N/A" && totalSystemCost > 0 && annualSavingsYear1 > 0) { paybackYears = "More than " + systemLifespan + " years"; } else if (totalSystemCost === 0 && annualSavingsYear1 > 0) { paybackYears = "0 years (no cost)"; } else if (annualSavingsYear1 0) { paybackYears = "No savings / Never"; } // Display results document.getElementById('outputSystemSize').innerText = requiredSystemSize_kW.toFixed(2) + ' kW'; document.getElementById('outputNumPanels').innerText = numPanels; document.getElementById('outputTotalCost').innerText = '$' + totalSystemCost.toFixed(2); document.getElementById('outputAnnualGeneration').innerText = annualGeneration_kWh.toFixed(0) + ' kWh'; document.getElementById('outputAnnualSavings').innerText = '$' + annualSavingsYear1.toFixed(2); document.getElementById('outputPaybackPeriod').innerText = paybackYears + (typeof paybackYears === 'number' ? ' years' : "); document.getElementById('outputTotalSavingsLifespan').innerText = '$' + totalSavingsOverLifespan.toFixed(2); document.getElementById('solarResults').style.display = 'block'; }

Understanding Your Solar Panel System

Solar panels convert sunlight into electricity, offering a sustainable way to power your home and reduce utility bills. The efficiency and output of a solar system depend on several key factors, which are reflected in the calculator above.

Key Factors Explained:

• Average Daily Electricity Consumption (kWh): This is how much electricity your household uses on a typical day. It's the primary driver for determining how large your solar system needs to be to meet your energy demands. You can usually find this on your electricity bill.
• Average Daily Peak Sun Hours (hours): Also known as "solar insolation," this measures the intensity and duration of sunlight your location receives. Areas with more peak sun hours can generate more electricity with fewer panels. This varies significantly by geographic location and season.
• Desired Solar Coverage (%): This allows you to specify what percentage of your electricity needs you want to cover with solar. You might aim for 100% to eliminate your bill, or a lower percentage to supplement your grid power.
• Current Electricity Cost ($/kWh): Your current electricity rate directly impacts your potential savings. Higher rates mean greater financial benefits from generating your own power.
• Solar Installation Cost ($/Watt): This is the average cost to purchase and install solar panels, typically ranging from $2.50 to $4.00 per watt, depending on location, equipment, and installer. This figure is crucial for calculating the total upfront investment.
• Individual Solar Panel Wattage (Watts): Standard solar panels come in various wattages (e.g., 300W, 400W, 500W). This input helps determine how many physical panels you'll need to achieve your desired system size.
• Annual Solar Degradation Rate (%): Solar panels gradually lose a small percentage of their efficiency each year. A typical degradation rate is around 0.5% per year, meaning a panel might produce 0.5% less power in its second year than its first.
• Annual Electricity Price Inflation (%): Electricity prices tend to increase over time. Factoring in an inflation rate helps project more realistic long-term savings, as the value of the electricity you generate will increase.
• System Lifespan for Savings (Years): This is the period over which you want to calculate your total savings. Most solar panels come with performance warranties of 20-25 years, making this a common timeframe for financial projections.

By understanding these variables, you can make informed decisions about investing in solar energy, contributing to a greener future while potentially saving a significant amount on your electricity bills.