Solar Panel Estimate Calculator

Solar Panel Estimate Calculator

Use this calculator to estimate the number of solar panels you might need, the total system size, and the approximate cost for your home based on your electricity consumption and local sunlight conditions.

function calculateSolarEstimate() { var monthlyKWhConsumption = parseFloat(document.getElementById('monthlyKWhConsumption').value); var dailySunlightHours = parseFloat(document.getElementById('dailySunlightHours').value); var desiredOffset = parseFloat(document.getElementById('desiredOffset').value); var panelWattage = parseFloat(document.getElementById('panelWattage').value); var systemCostPerWatt = parseFloat(document.getElementById('systemCostPerWatt').value); var resultDiv = document.getElementById('result'); resultDiv.innerHTML = "; // Clear previous results // Input validation if (isNaN(monthlyKWhConsumption) || monthlyKWhConsumption <= 0 || isNaN(dailySunlightHours) || dailySunlightHours <= 0 || isNaN(desiredOffset) || desiredOffset 100 || isNaN(panelWattage) || panelWattage <= 0 || isNaN(systemCostPerWatt) || systemCostPerWatt <= 0) { resultDiv.innerHTML = 'Please enter valid positive numbers for all fields. Desired Energy Offset must be between 1 and 100.'; return; } // System loss factor (accounts for inverter efficiency, wiring losses, temperature, etc.) var systemLossFactor = 0.80; // 20% system losses // 1. Calculate Daily kWh Needed (to offset) var dailyKWhNeeded = (monthlyKWhConsumption / 30) * (desiredOffset / 100); // 2. Calculate Estimated System Size (kW) // Formula: (Daily kWh Needed / Daily Sunlight Hours) / System Loss Factor var estimatedSystemSizeKW = (dailyKWhNeeded / dailySunlightHours) / systemLossFactor; // 3. Calculate Estimated Number of Panels // Convert system size to Watts: estimatedSystemSizeKW * 1000 var estimatedNumPanels = Math.ceil((estimatedSystemSizeKW * 1000) / panelWattage); // 4. Calculate Estimated Annual Energy Production (kWh) // Formula: System Size (kW) * Daily Sunlight Hours * 365 days * System Loss Factor var estimatedAnnualProductionKWh = estimatedSystemSizeKW * dailySunlightHours * 365 * systemLossFactor; // 5. Calculate Estimated System Cost // Formula: System Size (kW) * 1000 (to Watts) * Cost per Watt var estimatedSystemCost = (estimatedSystemSizeKW * 1000) * systemCostPerWatt; // Display results var resultsHTML = '

Your Solar Estimate:

'; resultsHTML += 'Daily Energy Target: ' + dailyKWhNeeded.toFixed(2) + ' kWh'; resultsHTML += 'Estimated System Size: ' + estimatedSystemSizeKW.toFixed(2) + ' kW'; resultsHTML += 'Estimated Number of Panels: ' + estimatedNumPanels + ' panels (based on ' + panelWattage + 'W panels)'; resultsHTML += 'Estimated Annual Energy Production: ' + estimatedAnnualProductionKWh.toFixed(0) + ' kWh'; resultsHTML += 'Estimated System Cost (before incentives): $' + estimatedSystemCost.toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ",") + "; resultsHTML += 'This is an estimate. Actual needs and costs may vary based on specific equipment, installation factors, shading, and local incentives.'; resultDiv.innerHTML = resultsHTML; } .calculator-container { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; background-color: #f9f9f9; padding: 25px; border-radius: 10px; box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1); max-width: 700px; margin: 30px auto; border: 1px solid #e0e0e0; } .calculator-container h2 { color: #2c3e50; text-align: center; margin-bottom: 20px; font-size: 28px; } .calculator-container p { color: #555; line-height: 1.6; margin-bottom: 15px; } .calc-input-group { margin-bottom: 18px; display: flex; flex-direction: column; } .calc-input-group label { margin-bottom: 8px; color: #34495e; font-weight: bold; font-size: 15px; } .calc-input-group input[type="number"] { padding: 12px; border: 1px solid #ccc; border-radius: 6px; font-size: 16px; width: 100%; box-sizing: border-box; transition: border-color 0.3s ease; } .calc-input-group input[type="number"]:focus { border-color: #28a745; outline: none; box-shadow: 0 0 5px rgba(40, 167, 69, 0.3); } .calc-button { background-color: #28a745; color: white; padding: 14px 25px; border: none; border-radius: 6px; cursor: pointer; font-size: 18px; font-weight: bold; display: block; width: 100%; margin-top: 25px; transition: background-color 0.3s ease, transform 0.2s ease; } .calc-button:hover { background-color: #218838; transform: translateY(-2px); } .calc-button:active { transform: translateY(0); } .calc-result-area { background-color: #e6ffe6; border: 1px solid #a3e6a3; border-radius: 8px; padding: 20px; margin-top: 30px; color: #218838; font-size: 17px; line-height: 1.8; } .calc-result-area h3 { color: #1e7e34; margin-top: 0; margin-bottom: 15px; font-size: 22px; text-align: center; } .calc-result-area p { margin-bottom: 10px; color: #333; } .calc-result-area p strong { color: #1e7e34; } .calc-result-area .disclaimer { font-size: 14px; color: #666; margin-top: 20px; text-align: center; } .calc-result-area .error { color: #dc3545; font-weight: bold; text-align: center; }

Understanding Your Solar Panel Estimate

Going solar is a significant investment that promises long-term savings and environmental benefits. Before you commit, getting a clear estimate of your potential solar system's size, cost, and energy output is crucial. Our Solar Panel Estimate Calculator helps you do just that, providing a preliminary understanding based on key factors.

How Solar Panel Estimation Works

The process of estimating your solar needs involves several critical inputs that reflect your energy consumption patterns and local environmental conditions:

• Average Monthly Electricity Consumption (kWh): This is the most fundamental input. Your electricity bill typically shows your monthly consumption in kilowatt-hours (kWh). This figure tells us how much energy your household uses, which directly dictates how much solar power you need to generate.
• Average Daily Peak Sunlight Hours: Not all sunlight is equal. "Peak sunlight hours" refer to the equivalent number of hours per day when sunlight intensity averages 1,000 watts per square meter. This value varies significantly by geographic location and time of year. A higher number of peak sunlight hours means your panels can produce more electricity daily.
• Desired Energy Offset (%): Do you want to cover 100% of your electricity needs with solar, or perhaps a smaller percentage? This input allows you to specify how much of your current consumption you aim to offset with solar energy.
• Typical Solar Panel Wattage (Watts): Solar panels come in various power ratings, commonly ranging from 300 to 450 watts per panel. Higher wattage panels can produce more electricity individually, potentially reducing the total number of panels required for a given system size.
• Estimated System Cost per Watt ($): This figure represents the average cost to install one watt of solar capacity, including panels, inverters, mounting hardware, labor, and permitting. This cost can vary widely based on location, installer, equipment quality, and system complexity.

What the Calculator Provides

Based on your inputs, the calculator provides several key outputs:

• Daily Energy Target: The average daily kWh your system needs to produce to meet your desired offset.
• Estimated System Size (kW): This is the total power output capacity of your solar array, measured in kilowatts (kW). A larger system size means more panels and higher overall energy production.
• Estimated Number of Panels: The approximate quantity of solar panels required to achieve your estimated system size, based on the typical panel wattage you provided.
• Estimated Annual Energy Production (kWh): The total amount of electricity your solar system is expected to generate over a year, measured in kWh. This helps you understand your potential savings.
• Estimated System Cost (before incentives): An approximate total cost for your solar installation before any federal, state, or local incentives (like tax credits or rebates) are applied.

Factors Influencing Your Solar Needs and Costs

While this calculator provides a solid starting point, several real-world factors can influence your final solar system design and cost:

• Roof Characteristics: Roof size, angle, orientation (south-facing is ideal in the Northern Hemisphere), and shading from trees or other buildings significantly impact panel placement and efficiency.
• System Efficiency Losses: Factors like temperature, dust, wiring losses, and inverter efficiency mean that panels rarely operate at their theoretical maximum. Our calculator uses a standard system loss factor, but actual losses can vary.
• Local Regulations and Permitting: Building codes, utility interconnection requirements, and local permitting processes can add to the complexity and cost of installation.
• Incentives and Rebates: Government tax credits (like the federal ITC), state rebates, and local utility programs can significantly reduce the net cost of your solar system. Always research what's available in your area.
• Battery Storage: If you're considering adding battery storage to your solar system for backup power or to maximize self-consumption, this will add to the overall cost and complexity.

Next Steps After Getting Your Estimate

This calculator is a powerful tool for initial planning. However, for a precise assessment and a firm quote, it's always recommended to:

1. Consult with Multiple Solar Installers: Get detailed proposals from several reputable local solar companies. They can perform a site-specific analysis, assess your roof, and provide accurate system designs and cost breakdowns.
2. Review Your Electricity Bills: Provide installers with a year's worth of electricity bills to help them accurately size a system that meets your historical consumption.
3. Understand Financing Options: Explore cash purchase, solar loans, and power purchase agreements (PPAs) to find the best financial fit for your situation.

By using this calculator and taking these next steps, you'll be well on your way to making an informed decision about going solar and enjoying the benefits of clean, renewable energy.