About ProSolarCalc

ProSolarCalc is a free set of solar, battery and electrical calculators with plain-English guides. It is built and maintained by Sri Murugan Systems, an independent software studio in Madurai, India.

Who builds it

The site is designed, written and coded by Murugan Vellaichamy, an independent software engineer, under Sri Murugan Systems. We are not a solar installer, an electrician or a financial adviser, and we don't present ourselves as one. Our job is to do the arithmetic carefully, show it, and point you to the official rules behind every policy figure.

Why it exists

Many solar calculators exist to collect your phone number for installers, so their maths stays shallow and their assumptions stay hidden. Here the calculator is the product: no signup, no contact form, and your inputs stay in your browser. Every calculator shows the formula it uses, so you can check the working.

How we check the numbers

• Official sources only. Subsidies, tariffs, tax credits and export rates come from the regulator or government body that sets them, such as MNRE and PIB in India, the IRS and CPUC in the US, Ofgem in the UK, the Bundesnetzagentur in Germany, NEPRA in Pakistan, the Clean Energy Regulator in Australia and NERSA in South Africa. Technical guides cite standards bodies and national laboratories (the NEC, NREL, Sandia, the EU's PVGIS). We don't use aggregator or installer sites as sources.
• Sources on the page. Every guide ends with a Sources list linking to the documents it relies on, and shows the date it was last reviewed.
• Tested before every release. Before each update goes live, automated checks compare calculator results with independently computed answers, fill every input with zero, typical and extreme values to catch errors, and check every page on phone, tablet and desktop widths.
• Regular reviews. Figures that change on a schedule, such as quarterly buyback prices, price caps and six-monthly feed-in or rebate steps, are re-checked when the regulator publishes new values. Changes to calculator data are recorded in the data changelog.

What the results are, and aren't

The calculators give planning estimates, not a system design or a quote. Real output depends on your roof, shading, equipment and local rules, and incentives change. Use the results to understand your options and to question a quote, then confirm the details with a qualified local installer and, for tax or loan decisions, a qualified adviser.

How the site is funded

ProSolarCalc is free to use. It may show advertising and may contain affiliate links, as described in our privacy policy. Neither affects how a calculator works or what result it gives, and we don't sell your data or pass your details to installers.

Found a mistake?

Corrections are welcome, especially with a link to an official source. Email us and we'll review it and update the page.

More ways to reach us are on the contact page.