About BulBat
What BulBat Is
BulBat is a small, independent, advertising-supported site built around six free calculators for solar, batteries, EV charging, and home carbon footprint, alongside a Batteries & Clean Energy museum and a Learn reference section. There is no company or support team behind it with a founding story worth telling — just a set of tools built to answer specific questions that come up when you’re sizing a battery bank, budgeting an EV, planning a solar array, or working out your household’s emissions.
How the Calculators Are Built
Every tool on BulBat runs a plain formula on the numbers you give it — there is no hidden model or lookup deciding your result. The Solar ROI Calculator takes your system size in kW, average peak sun hours for your location, electricity rate, and any upfront incentive, projects annual generation in kWh by multiplying system size by sun hours and days per year (with a standard performance allowance for inverter and wiring losses), values that generation at your electricity rate, and divides net system cost by annual savings to estimate a payback period and a 25-year return.
The EV Charging Cost Calculatorstarts from battery capacity and a charging-efficiency figure to separate the energy your car’s battery actually receives from the larger amount pulled from the wall, multiplies that grid draw by your electricity rate for a dollar cost, and divides by the vehicle’s efficiency in miles per kWh for range added and cost per 100 miles.
The Energy Storage Calculator sizes a battery bank the way an off-grid or backup system actually gets sized: daily energy use in kWh, multiplied by your chosen days of autonomy, divided by depth of discharge and system voltage, converted to both kWh and amp-hours. The Battery Runtime Calculatorruns a related relationship — amp-hour capacity times voltage times an efficiency factor gives usable watt-hours, which divided by your load in watts gives hours and minutes of runtime. The Battery Lifespan Calculatortakes a battery’s rated cycle count, adjusts it for how deeply you typically discharge it, and divides by how often you cycle it per week to estimate effective cycles remaining and calendar years of service.
The Carbon Footprint Calculatorapplies standard emissions factors — kilograms of CO₂-equivalent per kWh of grid electricity, per mile driven, and per therm of natural gas — to the home electricity, driving, and gas figures you enter, then totals them by category in kilograms and tonnes. None of these units or relationships are unique to BulBat; they are the same ones used in solar-industry and utility calculators generally, just built as free, no-login tools. The Batteries & Clean Energy museum and the Learn sections on Battery Basics, Solar & Renewables, EVs & Charging, and Home Energy & Lighting sit alongside the calculators for background reading, and are themselves drawn from Wikipedia and Wikimedia Commons rather than written from scratch.
What This Is (and Isn’t)
BulBat is independent and not affiliated with any solar manufacturer, battery maker, EV brand, utility, or government incentive program it references. It runs on advertising, which is how the tools stay free with no account and no paywall. Every result is an estimate built on the formulas above and on typical assumptions you can change — not a substitute for a site survey, an installer’s quote, or a professional energy audit. For electrical work, system design, or anything safety-related, talk to a licensed electrician or solar installer rather than relying on a calculator.
Found a number that looks off, or want a calculator for something not covered yet? Get in touch.