Privacy

Short version: this is a small, independent tool. It isn't trying to know who you are, and there's nothing to sell you. Here's exactly what does and doesn't happen with your data.

The calculator

Every number you enter stays in your browser. There's no account, no login, and nothing you type into the calculator is sent to a server. The "Create shareable link" button encodes your inputs directly into the URL — that link is the only way a scenario travels anywhere, and only if you choose to send it. While you work, the calculator keeps your inputs in this browser tab's session storage, so they survive a reload; that's cleared when you close the tab.

Your meter data (Green Button)

If you choose a Green Button file of your electricity use, your browser reads it on your device. It isn't uploaded and isn't included in share links. Its hourly readings are kept in this browser tab's session storage, so the rooftop and balcony calculators can both use them; they're deleted when you close the tab or click “Stop using it.” If you load it in the guided walkthrough, it's passed to the calculator the same way. The only thing fetched over the network is the small file reader the calculator loads the first time you choose a file. Nobody else sees your data, including me.

Cookies

The site doesn't set cookies. The light/dark theme toggle, and your progress through the simplified questionnaire if you use it, are remembered using your browser's local storage, not a cookie — both stay on your device and are never transmitted anywhere.

Hosting & delivery

Like effectively every website, this one runs on infrastructure that has to process basic connection information to deliver pages at all: your IP address, the page requested, a timestamp, and your browser's user agent. That happens here through Cloudflare (CDN, DNS, and abuse protection) and the hosting provider. Neither is used for anything beyond serving the site and defending it from abuse — see Cloudflare's own privacy policy for how they handle it.

Analytics

I count visits with Cloudflare Web Analytics. It sets no cookies, doesn't fingerprint your device and doesn't follow you to other sites. It tells me totals: which pages get visited, from which sites and countries, on what kind of device, and how fast the pages load. Never a profile tied to you, and never anything you type into a calculator. There is no Google Analytics, no ad pixel, and no retargeting tag anywhere on this site.

I also use Google Search Console, which shows me how the site appears in Google's search results: the searches it shows up for and how often people click through. That comes from Google's side of the search, not from anything on these pages.

The contact form

The contact form emails your name (if you give one), your email address, and your message directly to my inbox using the server's mail function. That's it — there's no database behind it, nothing is added to a mailing list, and it isn't shared with or sold to anyone. Two ordinary anti-spam checks run on submission (a hidden field real visitors never fill in, and a minimum time before submit) — neither collects anything beyond what's already in the form.

Third parties

The full list: Cloudflare (CDN, DNS, security) and the web host that serves the files and delivers contact-form email. No ad networks, no trackers, no data brokers, and no data is sold to anyone, ever.

Changes

If how this site handles data ever changes, this page changes with it. Last updated 2026-10-31.

Questions about any of this? Get in touch.