1 What this policy covers
This Cookie Policy explains how Solar Metrix uses cookies and similar browser technologies on solarmetrix.app, including the /tools/ calculators, the EV Cost Explorer at /ev/ev-calculator, the calculator guides, the installer directory, installer registration and Pro licence activation.
It should be read together with our About Contact Terms Disclaimer Methodology Privacy Policy, which explains the personal data we process, why we process it, who we share it with and your rights.
2 Cookies vs local storage
These technologies are often mentioned together, but they do different jobs:
| Technology | What it is | What we use it for |
|---|---|---|
| Cookies | Small text files set by a website and sent back with requests to that site or a third party. | Google Analytics 4 measurement cookies. |
| Local storage | A key-value store inside your browser. It is not sent with every web request. | Remembering calculator inputs, currency, location preference, licence state and UI choices. |
| IndexedDB | A browser database for larger or structured data. | Firebase Authentication's anonymous session state for licence verification. |
| Cache Storage | A store used by service workers to keep files available offline. | The installable EV app's offline assets. |
Local storage is not a cookie, but it is still data stored on your device. We list it here because you have the same interest in knowing what is saved and how to remove it.
3 Cookies we use
Calculator, guide, installer-directory and EV pages load Google Analytics 4 with the measurement ID G-NVMCWL5N3P. Google may set the following first-party cookies on the solarmetrix.app domain. The exact set can vary by browser, region and Google's configuration.
| Cookie | Provider | Purpose | Typical expiry | Category |
|---|---|---|---|---|
_ga |
Google Analytics | Distinguishes one browser or device from another so visits can be counted and attributed. | Up to 2 years | Analytics |
_ga_G-NVMCWL5N3P |
Google Analytics | Keeps session state for this specific GA4 property. | Up to 2 years | Analytics |
_gid |
Google Analytics | Distinguishes users for short-term reporting. It may be set in addition to _ga. |
Up to 24 hours | Analytics |
_gat or _gat_gtag_* |
Google Analytics | May be used to throttle request rates. It is short-lived and may not always be present. | About 1 minute | Analytics |
Google Analytics receives the cookie values, the page you visited, interaction events, your approximate location derived from your IP address, and technical information such as your browser, device, language and referring page. We do not send your calculator inputs, name, email address, phone number, licence key or coordinates to Google Analytics as event parameters.
Google acts as our analytics provider. Its handling of data is governed by the Google Privacy Policy and How Google uses information from sites that use its services.
Cookies we do not currently use
- No advertising or remarketing cookies at present (for example, Google Ads, DoubleClick or Meta Pixel). If we introduce them, this page will list the vendor, cookie name, purpose and duration before activation.
- No affiliate or partner-tracking cookies.
- No cross-site behavioural profiling cookies at present.
- No login or account cookies. The calculators do not require an account.
Advertising we may introduce
We do not currently display third-party advertisements. We may introduce advertising in future to fund the free calculators and guides.
If we do, vendors such as Google AdSense may set cookies or read device identifiers to select, deliver and measure ads. They may receive your IP address, approximate location, the page you are viewing and technical information about your browser or device. Some ads may be personalised based on your interests.
Where law requires it, we will show a consent banner or certified consent-management platform before any non-essential advertising cookie is set. You will be able to accept, refuse or withdraw consent without losing access to the calculators.
You can also control personalised advertising through Google Ads Settings (google.com/settings/ads) and the opt-out pages run by the Digital Advertising Alliance and EDAA. Blocking advertising cookies does not remove ads; it may make them less relevant.
What about this policy page?
The Privacy Policy and Cookie Policy pages do not load Google Analytics. They are plain, self-contained pages so that you can read about our data practices without being measured while you do so.
4 Local-storage keys
These keys are stored by your browser on your device. They are not sent to Solar Metrix as part of normal calculator use. Some keys only appear after you use the relevant tool; others are legacy keys kept so older saved projects still load.
| Key | Used by | Purpose | Kept until |
|---|---|---|---|
sm_currency | Main hub | Remembers your selected currency. | You clear site data |
sm_input_mode | Main hub | Remembers whether you chose the simple or advanced input mode. | You clear site data |
sm_pro_state | Main hub, Site Location, installer directory | Stores the shared bill, tariff, coordinates and core system summary so modules stay in sync. | You clear site data |
sm_geo_city | Main hub | Caches the place name returned for a set of coordinates, so the same lookup is not repeated. | You clear site data |
sm_pro_syssize | System Size, Solar Payback | Saves the system sizing result and inputs for reuse in the payback calculator. | You clear site data |
sm_fl_currency, sm_fl_state | Future Load | Remembers the selected currency and your future-appliance inputs. | You clear site data |
sm_pro_futureload | Future Load | Legacy key used to migrate older saved future-load projects. | You clear site data |
sm_pro_gridbat | Grid vs Battery | Legacy key for older saved grid-versus-battery projects. | You clear site data |
sm_gb_project | Grid vs Battery | Saves the current grid-versus-battery project inputs. | You clear site data |
sm_battery_backup_state | Battery Backup | Saves appliance loads, backup hours and battery choices. | You clear site data |
sm_battery_roi_state | Battery Backup, Battery ROI | Carries the battery specification into the ROI calculator. | You clear site data |
sm_roi_state | Solar Payback | Saves the payback calculator's system, tariff, battery, loan and export inputs. | You clear site data |
sm_emi_state | Solar EMI | Saves loan amount, interest rate, term, bill and battery inputs. | You clear site data |
sm_ss_state | String Sizing | Reset/legacy key used when clearing a string-sizing session. | You clear site data |
sm_user_loc | Installer directory | Remembers the approximate location you allowed so installers can be sorted by distance. | You clear site data |
sm_rater_token | Installer profile | A random token that stops the same browser submitting duplicate reviews. It is not your name or account ID. | You clear site data |
sm_installer_app | Installer signup | Stores a local confirmation reference after an installer application is submitted. | You clear site data |
sm_ev_mode | EV Cost Explorer | Remembers basic or advanced mode. | You clear site data |
sm_ev_suggest | EV Cost Explorer | Remembers whether suggestion hints are switched on. | You clear site data |
sm_ev_currency | EV Cost Explorer | Remembers your selected currency. | You clear site data |
sm_ev_state | EV Cost Explorer | Saves your vehicle, fuel, charging and solar inputs. | You clear site data |
solar_device_id | Yield Estimation (Pro) | A random device identifier used to enforce the licence device limit. It is not a hardware serial number. | You clear site data or deactivate the device |
solar_license_active | Yield Estimation (Pro) | Remembers that this device has an active licence. | You clear site data or deactivate the device |
solar_license_key | Yield Estimation (Pro) | Stores the licence key on this device so you do not have to re-enter it each visit. | You clear site data or deactivate the device |
solar_license_expiry | Yield Estimation (Pro) | Stores the licence expiry date for display. | You clear site data or deactivate the device |
current_solar_project | Yield Estimation | Saves the current project data for the yield calculator. | You clear site data |
solar_branding_config | Yield Estimation (Pro) | Stores report branding such as company name and logo. | You clear site data |
Clearing site data removes more than cookies. It also deletes saved calculator inputs, installer directory preferences and licence activation on that device. A Pro user may need to re-enter the licence key, subject to the device limit.
5 Offline app cache
The EV Cost Explorer can be installed as an app and may register a service worker. The service worker stores app files in a browser cache (named sm-ev-v2 in the current EV app) so the calculator can open without a network connection. It may cache the pages and assets you visited.
This cache stays on your device and is not sent to us. You can remove it by clearing site data for solarmetrix.app, clearing the app's storage in your device settings, or uninstalling the installed app.
6 Third-party requests
Some pages load libraries, fonts, maps or data from other providers. These requests can disclose your IP address, browser type and the page or asset requested, even when the provider does not set a cookie.
| Provider | Why it is contacted | Cookie use |
|---|---|---|
| Google Analytics | Aggregate usage measurement | Sets the analytics cookies listed above |
| Google Firebase | Installer registry, reviews, licence records and anonymous authentication | Uses browser storage/IndexedDB for auth state; not an advertising cookie |
| Make.com | Receives a quote-request webhook when you submit the form | No cookie set by our page |
| Open-Meteo | Historical weather and irradiance data | No cookie set by our page |
| OpenStreetMap Nominatim | Place search and reverse geocoding | No cookie set by our page |
| BigDataCloud | Reverse geocoding for city and currency suggestions | No cookie set by our page |
| Tailwind CSS, Google Fonts, jsDelivr, cdnjs and unpkg | Deliver page styling, fonts, icons, charting and PDF libraries used by calculators and guides | Normally none; standard request logs may apply |
| OpenStreetMap map embed | Show a map on some installer profiles | The embed provider may set its own storage or cookies |
These providers have their own privacy and cookie policies. We do not control their cookies or retention periods.
7 How to control them
Browser settings
Every major browser lets you view, block and delete cookies and site data. The controls are usually under Settings → Privacy and security (Chrome and Edge), Settings → Privacy (Safari) or Settings → Privacy & Security (Firefox). You can also use a private or incognito window, which normally clears local storage when you close it.
For step-by-step guidance across browsers, see aboutcookies.org.
Google Analytics opt-out
Google offers a browser add-on that prevents Google Analytics from collecting data on sites you visit: Google Analytics Opt-out Browser Add-on. Blocking or deleting the _ga cookies has the same effect for this site. Blocking analytics does not affect any calculator function.
Clear Solar Metrix site data
To remove everything this site has saved, open your browser's site-data settings for solarmetrix.app and choose Clear data or Delete site data. On mobile, you can also clear the app's storage from the device settings or uninstall the installed EV app.
Do you have to accept cookies?
No. The calculators work without analytics cookies. If you block them, the only loss is that we cannot count your visit in our aggregate reports.
8 Do Not Track and consent
Some browsers can send a Do Not Track (DNT) or Global Privacy Control (GPC) signal. We do not currently change our analytics behaviour based on those signals. You can block Google Analytics using the controls above.
Where local law requires consent before non-essential cookies are set, you can refuse or withdraw consent by blocking or deleting the analytics cookies, or by using the Google Analytics opt-out add-on. We do not use cookies to make decisions that have legal or similarly significant effects on you.
Current behaviour, stated plainly: Google Analytics loads automatically on calculator, guide, directory and EV pages. It does not load on this Cookie Policy page or the Privacy Policy page. We do not use a separate cookie-consent banner at this time. Before any advertising cookie is introduced, we will add a consent banner or certified consent-management platform and update this page.
9 Changes
We may update this policy if we add a cookie, change an analytics provider, introduce a consent tool or change how the calculators store data. The “Last updated” date at the top shows the current version. Material changes will be announced on the site or, where appropriate, by email to affected users.
10 Contact
If you have a question about cookies, browser storage or this policy, contact us:
Last updated: 22 October 2026. See also the About Contact Terms Disclaimer Methodology Privacy Policy.
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