Privacy policy

Information you give us

You can give us information in two places. The contact form takes an email address, an optional name, a subject and a message. The newsletter signup takes an email address and records which page you signed up from.

We use these to reply to you, to send you the newsletter you asked for, to keep records of correspondence, to detect and prevent abuse of the forms, and to understand which parts of the site people find useful. If we introduce further forms or features we will use the information they collect for the purposes described at the point of collection.

Contact messages are delivered through SendGrid and newsletter subscriptions are stored with Brevo, both acting as our processors. We retain correspondence for as long as it is useful and in any case no longer than two years. Newsletter subscriptions are kept until you unsubscribe.

Information collected automatically

We use Google Analytics 4 to count page views and understand which pages are useful. It sets cookies in your browser and collects your approximate location (from your IP address, which Google truncates), your device and browser type, the pages you view and how you arrived. We have not enabled Google Signals or advertising personalisation, so this is not used to build an advertising profile of you or to retarget you.

Our host, Vercel, keeps standard server logs including IP addresses for security and operational purposes.

The calculator

The calculator runs entirely in your browser. Your bill, your state and anything else you put into it are never transmitted anywhere, including to us. Nothing you calculate is stored.

This site sets analytics cookies through Google Analytics (names beginning _ga), which distinguish one visitor from another and expire after up to two years. We set no advertising cookies and no cookies of our own.

You can refuse all of it. Every major browser lets you block or delete cookies, and Google publishes a browser add-on that opts you out of Analytics entirely. Nothing on this site breaks if you do: every page is static and none of the content depends on being measured.

We honour Global Privacy Control signals where your browser sends one.

Some links to other companies are affiliate links, marked as such and explained on our disclosure page. Following one passes a referral identifier to that company so they know the visit came from us. It does not pass your name, your email or anything else about you, because we do not have those things unless you wrote to us.

Once you are on their site their privacy policy governs, not ours. If you give a company your phone number, you gave it to them. We never had it and cannot pass it on.

We share personal information only in these circumstances:

• With service providers who run parts of this site for us, under contract and only to provide that service. Today those are Vercel (hosting), SendGrid (contact email), Brevo (newsletter) and Google (analytics).
• Where you ask us to connect you with a company, and only what is needed to do it.
• Where we are required to by law, subpoena or other legal process, or where we believe in good faith it is necessary to protect rights, safety or property, or to investigate fraud or abuse.
• In connection with a merger, acquisition, financing or sale of all or part of this site or its business, in which case the recipient is bound by this policy until it gives notice of a change.

We do not sell personal information, and we do not share it for cross-context behavioural advertising, as those terms are defined in California law. We do not collect telephone numbers and we do not sell leads to installers. If that ever changed we would say so here and on the pages that promise it, before it changed, not after.

We may create and use aggregated or de-identified information, which cannot reasonably be used to identify you, for any purpose including analysis and publication. We will not attempt to re-identify it.

If you are in California, the CCPA as amended by the CPRA gives you the right to know what personal information we hold about you, to have it deleted, to correct it, and not to be discriminated against for asking. We do not sell or share personal information as those terms are defined in the Act, and we have no financial incentive programmes.

If you are in the UK or the EEA, you have the right to access, correct, erase, restrict and object to processing of your personal data, and to receive it in a portable form. Our lawful basis for replying to your message is legitimate interest in corresponding with you; for analytics it is consent, which you may withdraw by blocking cookies as described above.

Everyone else: ask us anyway, and we will do the same thing. It is easier than working out which rules apply.

To exercise any of this, write to us through the contact form. We will respond within 30 days. Because we hold almost nothing, most such requests are answered by telling you honestly that we have nothing on you beyond an email you sent us.

We take reasonable technical and organisational measures to protect what little we hold, including encryption in transit and access controls at our providers. No method of transmission or storage is completely secure, however, and we cannot guarantee absolute security of anything sent over the internet.

This site is not directed at children under 13 and we do not knowingly collect information from them. If you believe a child has sent us something, tell us and we will delete it.

We are based in the United States and our providers process data there. If you write to us from outside the US, your message is transferred there.

If this policy changes we will update the date at the top. Material changes will be described rather than quietly substituted.