About GainTally

Why GainTally?

Most clean energy calculators on the web are not designed to help you decide — they are designed to capture your contact information. The dominant business model in residential solar and HVAC online comparison is lead generation: you enter your zip code, system size, and email, and the site sells that record to local installers, typically for $50–$200 per qualified lead. The site is paid the moment you submit the form, regardless of whether you actually adopt solar, an electric vehicle, or a heat pump. That financial incentive pulls the entire user experience toward a single outcome: get the form filled. Estimates skew optimistic, break-even periods look shorter than they really are, and the calculator stops being a decision tool — it becomes a funnel.

We built GainTally because we wanted the opposite. We wanted a calculator that gives you the same number whether your answer is "yes, install solar this year" or "no, my roof faces the wrong direction and the payback is 22 years." We have no installer partners, we sell no leads, and our calculator results are yours alone — they never leave your browser unless you choose to share them. Our revenue comes from contextual display ads and, in the future, clearly labeled affiliate links to authoritative information sources. Neither depends on whether your calculation says yes or no.

Comparison reflects publicly observable business models as of 2026 and is provided for context, not as criticism of any individual platform.

Data Sources

Every calculator on this platform is powered by data from authoritative U.S. government and federal sources.

NREL— National Renewable Energy Laboratory

Solar irradiance & PVWatts API

Solar production estimates use NREL's PVWatts API, which provides zip-code-level irradiance data from decades of satellite observations. This ensures solar calculator outputs reflect your location's actual sunlight, not national averages.

EIA— U.S. Energy Information Administration

Electricity & natural gas rates

State-level electricity and natural gas prices are sourced from the EIA's open data API. Energy cost calculations use the most current available rate data for each state.

ENERGY STAR— EPA ENERGY STAR Program

Appliance & HVAC efficiency benchmarks

Appliance efficiency ratings and HVAC performance benchmarks come from the EPA's ENERGY STAR program. These ratings underpin heat pump, air conditioner, and appliance upgrade calculators.

IRS— Internal Revenue Service

Federal tax credit guidance

Federal clean energy tax credit eligibility references IRS guidance, including residential clean energy credit rules. Calculator outputs reflect the credit structure in effect at the time of calculation.

Founder & GainTally

GainTally is built and operated by Ender Yalçınkaya, a software engineer with a long-standing interest in residential energy efficiency, distributed solar, and the electrification of transportation. The project began as a personal frustration: every time I sat down to model a real-world clean energy decision — a heat pump for an older house, a 7 kW rooftop array, the all-in cost of switching to an EV — I either had to dig through three government data sets and a spreadsheet, or hand my contact information to a comparison site that would then sell it to installers. Neither felt right. GainTally is the tool I wished existed.

The platform is operated by GainTally, an independent publisher. The site runs on a Hetzner virtual private server behind a Cloudflare CDN, orchestrated by Coolify. There is no venture capital behind the project, no outside investors, and no acquisition pipeline — the project is bootstrapped and founder-funded.

How we make money

• Contextual display ads served through Google AdSense. Ads are shown only after you accept analytics & advertising cookies through our consent banner; otherwise the site runs without ad scripts loaded. We do not use personalized advertising profiles built from your browsing history.
• No sale of personal information. Your zip code, your email if you subscribe, and your calculator inputs are never sold, rented, or shared with third-party marketers.
• No installer referrals. The calculator does not route you to a paid network of contractors. Calculation results stay with you.
• No investor capital. The project is bootstrapped. There is no growth target that requires the calculator to optimize for conversions instead of accuracy.
• Future affiliate links, if added, will point to authoritative information sources (for example, state energy office guides or educational books) and will be labeled clearly. Affiliate links will never determine which answer the calculator gives you.

Our Promise to Visitors

We try to be the kind of site we would want to use ourselves. That means a small number of commitments that we will hold ourselves to publicly, and that you can hold us to as well.

• We will never sell your email or your zip code to a third party. Email subscriptions are optional, opt-in only, and you can unsubscribe with a single click from any email we send.
• Our analytics are anonymized. We use Google Analytics 4 and Microsoft Clarity with IP anonymization on and no cross-site fingerprinting. We do not build a personal profile of you; we look at aggregated traffic patterns to decide which calculators to improve next.
• We will not put a calculator behind a signup wall. All 20 calculators are free to use without an account, without an email address, and without dismissing a lead-capture popup.
• Our formulas stay open. Every calculator's formula, assumptions, and data sources are documented on the Methodology page. If you think a number looks off, you can read exactly how we got there and tell us where you disagree.
• We aim to publish aggregate usage stats once traffic stabilizes. Our internal target for the first quarter after launch is 5,000–15,000 monthly active users; once we have enough data to be meaningful, we plan to share anonymized, aggregated traffic and calculator usage numbers on a recurring basis.

Full details on what we collect and how we handle it live in our Privacy Policy and Terms of Use.

How Users Benefit

Homeowners across the US use GainTally to make confident clean energy decisions with real data — not sales estimates.