Cut your electricity bill.
See exactly what it would take.
Start with your location — your phone knows it — and we size every option that could cut your bill, from 1% all the way to producing a sellable surplus. For any amount you could spend, the price-cut curve shows what it buys, in your local currency. Educational estimates only, nothing for sale. Built and given away by Lucas Ballek.
Find your cheapest path to lower bills
Enter your location and average electric bill. We simulate 5 years of hourly NASA satellite weather to size the exact solar panel array and battery storage you need — with honest 20-year payback, battery replacement cadence, and equipment costs in your local currency.
Satellite imagery (no account needed) loads only after you ask for it. Coordinates go to the map tiles and NASA weather; nothing is saved.
I run a generator — what does its power really cost?
Assumes a small genset at typical partial load: petrol ≈ 0.5 L/kWh, diesel ≈ 0.35 L/kWh (fuel only — oil, filters, and engine wear push the true number higher). If you know your real $/kWh, type it directly instead.
Wattages are typical values — yours may differ. Cycling appliances (fridges, freezers, air conditioners, pumps) only draw power while running: their slider is hours actually running per day, capped to realistic compressor time, and each row shows the resulting 24-hour average. A modern fridge at the default (100 W running, ~10 h/day) really does use about 1 kWh/day.
Bills include fixed charges and taxes, so this slightly overestimates real use — which is a safe direction to err.
A rough manual estimate is enough: about 6 m² per 400 W panel. This only caps the searched solar size; leave it blank for the normal estimate. Your coordinates are never stored.
85–100; 98 is typical
90–100; 98 is typical
How many of your currency equal 1 US dollar. Auto-filled for your location; change only if you know a different rate.
Results appear here: a recommended path first, with battery comparisons and all options available below. For grid-tied plans, the result also separates bill reduction from outage backup.
How this was calculated
Run a sizing first - every constant used (derates, temperature model, efficiencies, weather data years and source) is listed here.
What a ~100 kWh Build Is Made Of
A reference parts list so you know what the pieces are and roughly what they cost. Nothing here is sold by this site — prices are indicative figures seen on the open market and change constantly.
EVE MB31 3.2V 314Ah Cells
Brand new Grade-A prismatic LFP cells. 16S configuration per pack (51.2V nominal).
JK 200A Active Balance BMS
Smart active balancing (2A balance current), dual temperature probes, RS485/CANbus comms with Sol-Ark & Victron.
Eaton Class-T 200A Fuses
20kA AIC interrupt rating @ 160V DC. Clears very high short-circuit DC currents in milliseconds — sized to protect the BMS and wiring.
300 kgf Compression Racks
Belleville spring washer endplates hold uniform compression (about 3,000 N). Manufacturers cite cycle-life benefits; treat specific gains as unverified.
Common Questions
Short answers to what people ask most. The AI advisor can go deeper on any of these.
How accurate are the estimates?
Every number comes from testable code simulating your exact location against five years of NASA satellite weather - not an AI guessing. Real-world results still vary with shading, installation quality, and hardware, so have a licensed professional verify anything you build.
Will a system pay for itself?
Where grid power is expensive - Hawaii, islands, much of Europe, Africa, South Asia - properly built solar plus storage commonly repays its component cost in one to four years, then runs nearly free for decades. The calculator shows your personal payback from your own tariff.
What does a system actually cost?
Battery banks self-built from prismatic cells typically land around $80–125 per usable kWh shipped and duty-paid; budget retail packs run roughly $110–165. Panels add about $0.16–0.38 per watt. Every result states its price scope honestly.
Do I need a generator?
Only if you want near-total independence through weeks of bad weather. The three off-grid options show exactly that trade-off: one never needs a generator, one needs it about a day a year, one only now and then. Grid-connected users skip this entirely.
Does it work without internet?
Yes. After your first visit the tool installs itself as an offline app: sizing math runs entirely in your browser, and if the network is down it falls back to bundled typical-year weather for the nearest of 66 reference cities.
Is building my own battery safe?
It demands respect: lithium cells store enough energy to start fires, and DC arcs don't switch off. The guides here insist on proper fusing, BMS use, and code compliance - and on having a licensed electrician check anything before you energize it.
Support This Tool
This is free and always will be. If it helped you and you want to chip in toward the AI and hosting costs, here's where.
Contributions go directly to Lucas Ballek personally.
Please read before sending anything. Contributions are voluntary gifts to an individual, not payment for a service. They are not tax-deductible — this is not a charity or a registered nonprofit. They buy nothing: no priority, no features, no personal advice, no support obligation, and no continued availability of this site. Everyone gets exactly the same free tool whether they contribute or not. Please don't send money you need. If you were hoping to pay for professional engineering help, spend it on a licensed local engineer or electrician instead — that is genuinely the better use of it.
Terms & Disclaimer
Short version: this is a free educational toy that produces rough estimates, run by one person, with no warranty of any kind.
Estimates, not engineering
Output is an automated educational estimate. It is not engineering, not a stamped design, not a quote, and not a safety certification. It may be wrong. Have any real system reviewed by a licensed electrician or engineer before you build or energize it.
You are talking to an AI
The advisor is a large language model. It generates plausible-sounding text and can state wrong numbers with total confidence. Treat every figure as a starting point to check, never as fact.
No accounts, no tracking
No signup, no cookies for advertising, no analytics profile. Your chat text is sent to the AI provider to generate a reply and is not stored here. Don't type anything sensitive into it.
Questions the AI couldn't answer?
You're welcome to email me: lucasballek@gmail.com
This is one person answering email in his own time, as a favor — not a support desk. I read what I can and reply when I'm able, but I can't promise a response or a timeframe. Anything I send back is a friendly opinion for your own further research, not professional engineering, electrical, or financial advice, and it doesn't create any professional relationship or obligation. For anything you're going to actually build, energize, or spend real money on, please talk to a licensed electrician or engineer in your area.