Solar Energy Tools

Free calculators and tools to help you plan your solar energy system and maximize savings.

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System Size Calculator

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Determine the optimal solar system size for your home based on energy consumption and roof space.

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Battery Storage ROI Analyzer

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Calculate battery storage ROI and payback period for your solar system with state-specific net metering policy analysis, time-of-use rate optimization, and Virtual Power Plant (VPP) revenue estimation.

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Battery-Only Payback Calculator

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Find out at what price home battery storage makes sense — with or without solar. See payback period, 10-year net savings, break-even battery price, and Virtual Power Plant revenue for your state.

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Carbon Offset Calculator

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Calculate how much CO2 emissions you can offset by switching to solar energy.

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Solar Surcharges & Hidden Costs Calculator

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Reveal the true cost of going solar by exposing hidden fees, non-bypassable utility charges, income-graduated fixed charges, minimum bills, and interconnection costs that solar salespeople routinely omit from their quotes.

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Panel Comparison Tool

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Compare solar panels side-by-side on efficiency, warranty, degradation, and cost per watt.

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Inverter Comparison Tool

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Compare solar inverters by type, warranty, price, and reliability. Filter string, microinverter, DC optimizer, and hybrid inverters with community-based reliability ratings.

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Energy Bill Analyzer

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Analyze your electricity bill to discover usage patterns, identify savings opportunities, and see how much solar panels could save you.

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PPA Contract Decoder & Red Flags Guide

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Decode your solar PPA or lease contract. Identify red flags like FMV buyout traps, escalator clauses, hidden dealer fees, and transfer restrictions before you sign.

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PPA Offer Value Analyzer — Is This PPA a Good Deal?

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Enter a solar PPA offer (rate, escalation, term) and compare its true 25-year cost against projected utility rates. See total savings, break-even year, and red-flag warnings for unfavorable terms.

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Solar + EV Savings Calculator

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Calculate combined solar panel and EV charging savings — annual and 25-year financial projections, optimal system sizing, and CO₂ reduction with real EPA vehicle data.

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PV Degradation Projector — 25-Year Output

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Project your solar panel energy output over 25 years accounting for panel degradation. Compare premium, standard, and budget panel tiers with warranty threshold analysis.

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DIY Solar Cost & Permit Complexity Estimator

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Estimate your total DIY solar installation cost including permit fees and interconnection by jurisdiction. See your permit complexity badge by ZIP code, full cost breakdown, and compare DIY vs professional install quotes.

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Solar Battery Bank Sizing Calculator

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Calculate exactly how many batteries you need for backup power based on your usage and outage duration. Compare LFP, NMC, lead-acid, and Tesla Powerwall options with state incentive-adjusted costs.

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Heat Pump Savings Calculator

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Compare heat pump vs gas furnace vs electric resistance heating costs for your home. See annual operating cost, 10-year savings, CO2 reduction, and payback with HEEHRA/HOMES rebates by state — using EIA 2026 energy rates and your climate zone.

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Coming Soon

Confused about solar tax credits after 2025?

The 30% ownership credit (Section 25D) ended under the OBBBA, but the Section 48E credit still makes solar affordable through leases and PPAs. Read our complete transition guide to see what it means for your numbers.

Read the Guide →

Written & reviewed by

EnergyTools Research Team — Solar Energy Research Group

The EnergyTools Research Team compiles and verifies residential solar data from NREL, EPA, and state utility commissions. Methodology is reviewed quarterly.

  • Source data: NREL PVWatts V8 + Utility Rates V3 APIs
  • Source data: EPA FuelEconomy.gov vehicle efficiency data
  • Methodology reviewed quarterly

Methodology & data sources:NREL PVWatts, EPA FuelEconomy.gov, state utility commissions— updated 2026.