Estimate your potential savings by installing solar panels on your roof.
(This varies by location, orientation, and shading)
Understanding Your Solar Roof Savings
Installing a solar roof system is a significant investment, but it offers substantial long-term financial and environmental benefits. This calculator helps you estimate your potential savings by considering key factors related to your energy consumption, the solar system's performance, and its cost.
How the Calculation Works:
Annual Electricity Cost: This is your current yearly expense on electricity. It's calculated by multiplying your Annual Electricity Usage (kWh) by the Average Electricity Cost per kWh ($). This gives us a baseline of what you spend without solar.
Potential Solar Energy Production: We estimate how much electricity your solar panel system can generate annually. This is determined by multiplying the Solar Panel System Size (kWp) by the Annual Solar Production Factor (kWh/kWp). The production factor is crucial and depends heavily on your geographical location, the angle and direction of your roof, and any shading from trees or buildings.
Estimated Annual Solar Savings: This is the core of the calculation. We assume that the electricity generated by your solar panels offsets your grid electricity consumption. Therefore, the estimated annual savings are calculated as: Potential Solar Energy Production (kWh) multiplied by the Average Electricity Cost per kWh ($).
Net System Cost: This is the actual upfront cost you'll pay for the solar system after accounting for financial assistance. It's calculated as the Total Solar Panel System Cost ($) minus any applicable Incentives & Rebates ($).
Payback Period (Years): This estimates how long it will take for the accumulated savings to cover the net cost of the system. It's calculated as the Net System Cost ($) divided by the Estimated Annual Solar Savings ($).
Total Lifetime Savings: Over the estimated lifespan of the system (e.g., 25 years), this represents the total financial benefit. It's calculated as: (Estimated Annual Solar Savings ($) * Estimated System Lifespan (Years)) – Net System Cost ($).
Key Factors to Consider:
Location and Sunlight: The amount of direct sunlight your roof receives is the most critical factor in solar production. Areas with more consistent sunshine will yield higher energy production.
System Size (kWp): This refers to the peak power output of the solar panels under standard test conditions. A larger system can generate more electricity but also costs more upfront.
Electricity Rates: Fluctuations in electricity prices can significantly impact your long-term savings. Higher future rates mean greater savings from solar.
Incentives and Rebates: Government and local incentives can substantially reduce the initial cost of a solar installation, shortening the payback period.
System Efficiency and Degradation: Solar panels degrade slightly over time, reducing their output. Reputable installers use panels with warranties that account for this.
Net Metering Policies: Understand your local utility's policies for crediting excess solar energy sent back to the grid.
This calculator provides an estimate. For a precise quote and assessment, consult with certified solar installation professionals who can evaluate your specific property and energy needs.
function calculateSolarSavings() {
var annualElectricityUsage = parseFloat(document.getElementById("annualElectricityUsage").value);
var electricityCostPerKwh = parseFloat(document.getElementById("electricityCostPerKwh").value);
var solarPanelSystemSize = parseFloat(document.getElementById("solarPanelSystemSize").value);
var annualSolarProductionFactor = parseFloat(document.getElementById("annualSolarProductionFactor").value);
var solarPanelCost = parseFloat(document.getElementById("solarPanelCost").value);
var incentivesAndRebates = parseFloat(document.getElementById("incentivesAndRebates").value);
var systemLifespanYears = parseFloat(document.getElementById("systemLifespanYears").value);
var resultDiv = document.getElementById("result");
resultDiv.innerHTML = ""; // Clear previous results
// Input validation
if (isNaN(annualElectricityUsage) || annualElectricityUsage <= 0 ||
isNaN(electricityCostPerKwh) || electricityCostPerKwh <= 0 ||
isNaN(solarPanelSystemSize) || solarPanelSystemSize <= 0 ||
isNaN(annualSolarProductionFactor) || annualSolarProductionFactor <= 0 ||
isNaN(solarPanelCost) || solarPanelCost < 0 || // Cost can be 0, but not negative
isNaN(incentivesAndRebates) || incentivesAndRebates < 0 ||
isNaN(systemLifespanYears) || systemLifespanYears <= 0) {
resultDiv.innerHTML = "Please enter valid positive numbers for all fields.";
return;
}
// Calculations
var annualElectricityCost = annualElectricityUsage * electricityCostPerKwh;
var potentialSolarProduction = solarPanelSystemSize * annualSolarProductionFactor;
var estimatedAnnualSolarSavings = potentialSolarProduction * electricityCostPerKwh;
var netSystemCost = solarPanelCost – incentivesAndRebates;
var paybackPeriod = netSystemCost / estimatedAnnualSolarSavings;
var totalLifetimeSavings = (estimatedAnnualSolarSavings * systemLifespanYears) – netSystemCost;
// Ensure net system cost is not negative after rebates
if (netSystemCost < 0) {
netSystemCost = 0;
paybackPeriod = 0; // If cost is 0, payback is immediate
}
// Display results
var htmlOutput = "Your Estimated Annual Electricity Cost (Without Solar): $" + annualElectricityCost.toFixed(2) + "";
htmlOutput += "Your System's Estimated Annual Solar Production: " + potentialSolarProduction.toFixed(0) + " kWh";
htmlOutput += "Estimated Annual Savings from Solar: $" + estimatedAnnualSolarSavings.toFixed(2) + "";
htmlOutput += "Net Cost of Solar System (After Rebates): $" + netSystemCost.toFixed(2) + "";
if (estimatedAnnualSolarSavings > 0) {
htmlOutput += "Estimated Payback Period: " + paybackPeriod.toFixed(1) + " Years";
} else {
htmlOutput += "Estimated Payback Period: N/A (Savings do not cover costs)";
}
htmlOutput += "Estimated Total Lifetime Savings (" + systemLifespanYears + " Years): $" + totalLifetimeSavings.toFixed(2) + "";
resultDiv.innerHTML = htmlOutput;
}