Solar Calculator Panels

Solar Panel Sizing & Savings Calculator

Your Solar Estimation:

Estimated Total System Size: —

Number of Solar Panels Needed: —

Estimated Annual Energy Production: —

Estimated System Installation Cost: —

Estimated Annual Electricity Bill Savings: —

function calculateSolar() { var dailyKWH = parseFloat(document.getElementById('dailyKWH').value); var peakSunHours = parseFloat(document.getElementById('peakSunHours').value); var panelWattage = parseFloat(document.getElementById('panelWattage').value); var systemLosses = parseFloat(document.getElementById('systemLosses').value); var costPerWatt = parseFloat(document.getElementById('costPerWatt').value); var electricityCost = parseFloat(document.getElementById('electricityCost').value); var resultsDiv = document.getElementById('solarResults'); var resultTotalSystemSize = document.getElementById('resultTotalSystemSize'); var resultNumPanels = document.getElementById('resultNumPanels'); var resultAnnualProduction = document.getElementById('resultAnnualProduction'); var resultEstimatedSystemCost = document.getElementById('resultEstimatedSystemCost'); var resultAnnualSavings = document.getElementById('resultAnnualSavings'); // Input validation if (isNaN(dailyKWH) || dailyKWH <= 0 || isNaN(peakSunHours) || peakSunHours <= 0 || isNaN(panelWattage) || panelWattage <= 0 || isNaN(systemLosses) || systemLosses 100 || isNaN(costPerWatt) || costPerWatt <= 0 || isNaN(electricityCost) || electricityCost <= 0) { resultsDiv.innerHTML = '

Please enter valid positive numbers for all fields. System losses must be between 0-100%.

'; return; } var systemLossesDecimal = systemLosses / 100; // 1. Calculate Total DC System Size (kW) // This is the DC system size required to meet the daily KWH demand, accounting for losses. var totalSystemSizeKW = (dailyKWH / peakSunHours) / (1 – systemLossesDecimal); var totalSystemSizeWatts = totalSystemSizeKW * 1000; // 2. Calculate Number of Solar Panels Needed var numPanels = Math.ceil(totalSystemSizeWatts / panelWattage); // 3. Calculate Estimated Annual Energy Production (kWh/year) // This is the actual energy produced by the calculated system size. var annualProductionKWH = totalSystemSizeKW * peakSunHours * 365 * (1 – systemLossesDecimal); // 4. Calculate Estimated System Installation Cost ($) var estimatedSystemCost = totalSystemSizeWatts * costPerWatt; // 5. Calculate Estimated Annual Electricity Bill Savings ($/year) var annualSavings = annualProductionKWH * electricityCost; resultTotalSystemSize.innerHTML = 'Estimated Total System Size: ' + totalSystemSizeKW.toFixed(2) + ' kW'; resultNumPanels.innerHTML = 'Number of Solar Panels Needed: ' + numPanels + ' panels'; resultAnnualProduction.innerHTML = 'Estimated Annual Energy Production: ' + annualProductionKWH.toFixed(0) + ' kWh/year'; resultEstimatedSystemCost.innerHTML = 'Estimated System Installation Cost: $' + estimatedSystemCost.toFixed(2); resultAnnualSavings.innerHTML = 'Estimated Annual Electricity Bill Savings: $' + annualSavings.toFixed(2) + '/year'; }

Understanding Your Solar Panel Needs

Going solar is a significant investment that can lead to substantial long-term savings and environmental benefits. However, determining the right size and cost of a solar panel system for your home can be complex. Our Solar Panel Sizing & Savings Calculator simplifies this process, providing you with a clear estimate of your potential solar setup.

How Solar Panels Work

Solar panels, also known as photovoltaic (PV) panels, convert sunlight into electricity. Each panel contains multiple solar cells made of semiconductor materials, typically silicon. When sunlight hits these cells, it excites electrons, creating an electric current. This direct current (DC) electricity is then sent to an inverter, which converts it into alternating current (AC) electricity – the type used to power your home appliances.

The amount of electricity a solar panel system generates depends on several factors, including the number and efficiency of the panels, the amount of sunlight they receive, and the overall system design.

Key Factors in Solar Panel Sizing

Our calculator takes into account several crucial inputs to give you an accurate estimate:

Average Daily Electricity Usage (kWh)

This is the most critical factor. It represents how much electricity your household consumes on an average day. You can find this information on your monthly electricity bills. A typical U.S. home might use around 30 kWh per day, but this varies greatly depending on household size, appliance usage, and climate control.

Average Daily Peak Sun Hours (hours)

Peak sun hours refer to the intensity of sunlight your location receives, equivalent to one hour of direct, full-intensity sunlight. It's not just about how many hours the sun is out, but how strong it is. This value varies significantly by geographic location and season. For example, a sunny state like Arizona might have 5-6 peak sun hours, while a cloudier region might have 3-4. You can find this data for your specific area online or from solar installers.

Individual Panel Wattage (Watts)

This is the power output rating of a single solar panel under standard test conditions. Modern residential solar panels typically range from 300 to 450 watts. Higher wattage panels can generate more electricity in a smaller footprint, potentially reducing the number of panels needed.

System Losses (%)

No solar system operates at 100% efficiency. Various factors contribute to energy loss, including:

• Temperature: Panels become less efficient at very high temperatures.
• Wiring: Some energy is lost as heat in the electrical wiring.
• Dust and Dirt: Accumulation on panels reduces sunlight absorption.
• Inverter Efficiency: Inverters aren't 100% efficient in converting DC to AC.
• Shading: Even partial shading can significantly impact output.

Typical system losses range from 15% to 25%. Our calculator uses a common average of 18%.

Estimated System Cost per Watt ($/Watt)

This figure represents the average cost to purchase and install a solar system, divided by its total wattage. This cost can vary widely based on location, equipment quality, installer, and system size. National averages often fall between $2.50 to $4.00 per watt before incentives.

Current Electricity Cost ($/kWh)

Your current electricity rate is essential for calculating potential savings. This is the price you pay per kilowatt-hour (kWh) for electricity from your utility company. It can vary by time of day, season, and utility provider.

Understanding Your Results

Once you input your details, the calculator will provide:

• Estimated Total System Size (kW): The total DC wattage your solar array needs to be to meet your daily electricity demands.
• Number of Solar Panels Needed: The approximate quantity of panels required based on your chosen individual panel wattage.
• Estimated Annual Energy Production (kWh/year): The total amount of electricity your system is expected to generate annually.
• Estimated System Installation Cost ($): A rough estimate of the total cost of your solar system before any tax credits or incentives.
• Estimated Annual Electricity Bill Savings ($/year): How much you could potentially save on your electricity bills each year by generating your own power.

Example Scenario:

Let's consider a typical home:

• Average Daily Electricity Usage: 30 kWh
• Average Daily Peak Sun Hours: 4.5 hours
• Individual Panel Wattage: 400 Watts
• System Losses: 18%
• Estimated System Cost per Watt: $3.00/Watt
• Current Electricity Cost: $0.15/kWh

Based on these inputs, the calculator would estimate:

• Estimated Total System Size: Approximately 8.13 kW
• Number of Solar Panels Needed: Around 21 panels (8130W / 400W per panel = 20.325, rounded up to 21)
• Estimated Annual Energy Production: Approximately 10,950 kWh/year
• Estimated System Installation Cost: Approximately $24,390 (8130W * $3.00/W)
• Estimated Annual Electricity Bill Savings: Approximately $1,642.50/year (10950 kWh * $0.15/kWh)

This example demonstrates how the calculator provides a comprehensive overview, helping you visualize the scale and financial implications of a solar investment.

Next Steps

While this calculator provides a solid estimate, it's important to remember that these are projections. For a precise quote and detailed system design, it's always recommended to consult with local solar professionals. They can assess your specific roof space, shading issues, local regulations, and available incentives to provide a tailored solution.