Terms of Sale & Digital Product Terms

Last updated: September 23, 2026

These Terms apply when you purchase a digital product from GreenWattWise Lab: the Home Battery Buyer Toolkit, the Home Battery Buyer Toolkit — Essential Edition, and/or the Home Battery Decision Calculator, as actually offered for sale at the time of your order. They are separate from, and in addition to, the product-specific License & Terms (Version 1.1 — EU Consumer Edition) supplied with each product, which governs what you may do with the files themselves once you own them.

1. Scope

These Terms apply to every purchase of a GreenWattWise Lab digital product made through the checkout links on greenwattwiselab.com, which currently route to Gumroad. They apply alongside, and do not replace, Gumroad's own Terms of Service (gumroad.com/terms), which you also accept when completing a purchase there.

2. Seller identity

Ernesto Ortega Díaz
Sapphogasse 12/9, 1100 Wien, Austria
Email: greenwattwiselab@gmail.com

GreenWattWise Lab is operated by Ernesto Ortega Díaz as a private individual. Business registration number: not applicable. VAT identification number: not applicable — not currently VAT-registered. See Legal Notice / Imprint for the full identification required under German/Austrian law.

3. Products

The digital products currently offered are the Home Battery Buyer Toolkit, the Home Battery Buyer Toolkit — Essential Edition, and the Home Battery Decision Calculator. Each product page on this site describes what is included. Not every product is necessarily available for individual purchase at all times — see the relevant product page for its current availability and purchase link.

4. Educational nature of the products

These products provide educational, decision-support information for homeowners comparing home-battery options. They are not electrical engineering or system-design services, installation advice, individualized financial or investment advice, tax advice, or legal advice. Nothing supplied with these products replaces verification of an actual system design, electrical compatibility, installation requirements, or equipment specifications by a qualified installer, equipment manufacturer, or other appropriately qualified local professional.

5. Contract formation

Purchases are processed through Gumroad. Placing an order on Gumroad is an offer to purchase; Gumroad's own checkout confirms when that offer is accepted and payment is completed. Gumroad acts as merchant of record for these transactions (see Legal Notice / Imprint and the Gumroad compliance review referenced in section 20 below); the precise contractual mechanics between you, Gumroad, and Ernesto Ortega Díaz as the underlying content provider are set out in Gumroad's own Terms of Service.

6. Prices

The price for a product is the price shown on its Gumroad product page at the time you complete your purchase. Prices are not listed on this website itself and may change; the price you agree to pay is the one displayed at checkout before you confirm payment.

7. Taxes / VAT

Gumroad calculates, collects, and remits applicable consumption tax (including EU VAT) on qualifying sales as merchant of record, in addition to the seller's listed price. The VAT rate applied depends on your country of residence under the EU's destination principle. This applies regardless of Ernesto Ortega Díaz's own VAT-registration status (see section 2 above).

8. Payment

Payment is handled entirely by Gumroad using the payment methods Gumroad offers at checkout. GreenWattWise Lab does not receive or store your payment card or bank details.

9. Digital delivery

Products are delivered digitally, immediately after payment, via a download link and/or email from Gumroad. No physical item is shipped. See section 15 (Withdrawal) for how immediate delivery interacts with your statutory withdrawal right.

10. Personal-use license

Your purchase grants you a personal, non-transferable license to use the files for your own household's decision-making, on the terms set out in full in the product's License & Terms document (Version 1.1 — EU Consumer Edition), included as a file inside the product download itself. That document, not this summary, governs what you may and may not do with the files.

11. Intellectual-property restrictions

Except where applicable law expressly permits otherwise, you may not redistribute, resell, sublicense, publicly upload, commercially share, rebrand, or create competing products from these files or substantial portions of their content. The full list of restrictions is in the License & Terms document referenced in section 10.

12. Calculator assumptions

The Home Battery Decision Calculator and the free sizing calculator distinguish the figures you enter (user inputs) from the assumptions built into the tool (for example usable battery capacity, round-trip efficiency, and tariff assumptions) and from the figures the tool calculates from them. Results are estimates and comparison aids based on the inputs and assumptions used — they are not guaranteed predictions of savings, system performance, battery life, backup duration, or financial return, and are not a final electrical or engineering design.

13. Technical requirements

PDF guides require a modern PDF reader. The spreadsheet-based Decision Calculator requires Microsoft Excel, LibreOffice Calc, or comparable spreadsheet software capable of opening .xlsx files. The free web calculator requires a modern JavaScript-enabled browser. We have not tested every possible reader, spreadsheet application, or browser and do not claim compatibility beyond what is stated here.

14. Statutory conformity / warranty rights

If the digital content you receive is defective, incomplete, or does not match its description, you have statutory rights relating to non-conforming digital content under applicable EU/national consumer law. These rights are separate from, and not time-limited in the way that, the 14-day withdrawal right described in section 15, and are not affected by any consent you gave to immediate delivery.

15. Withdrawal rights

If you are an EU/EEA consumer, you generally have a statutory right to withdraw from your purchase within 14 days. Because these products are supplied digitally and immediately, that right can end early only if you gave express, informed consent to immediate supply and acknowledged that doing so ends your withdrawal right. See Withdrawal for the full explanation, including how to exercise this right and how it differs from your conformity rights under section 14.

16. Liability

These products provide educational decision-support information and are not a substitute for professional electrical, engineering, installation, financial, tax, or legal advice. Ernesto Ortega Díaz is not responsible for outcomes resulting from inaccurate or incomplete information you or a third party supply, or from changes in tariffs, incentives, product specifications, warranty terms, grid requirements, or other external information after publication, to the extent permitted by applicable law. Nothing in these Terms excludes or limits liability where such exclusion or limitation is prohibited by applicable law, including liability for intent or gross negligence, or liability for injury to life, body, or health.

17. Consumer rights

Nothing in these Terms limits or excludes mandatory consumer rights available to you under applicable law, including the rights described in sections 14 and 15 above.

18. Applicable law

These Terms are governed by the law of Austria. If you are a consumer habitually resident in another country, this choice of law does not deprive you of mandatory consumer protections that apply to you under the law of your country of habitual residence.

19. Consumer dispute information

The European Commission's online dispute resolution (ODR) platform, which the EU previously required online sellers to link to, was permanently closed to new complaints on 20 March 2025 and shut down entirely on 20 July 2025; EU sellers are no longer required (or able) to link to it, so no such link is provided here. If you have a complaint, please contact us first using the details in section 2 — we have not independently confirmed whether a specific national alternative-dispute-resolution (ADR) body applies to this seller, and this will be reviewed as EU rules in this area continue to develop.

20. Contact information

Ernesto Ortega Díaz · greenwattwiselab@gmail.com
Sapphogasse 12/9, 1100 Wien, Austria

These Terms do not attempt to contract out of mandatory consumer protection law. They are a pre-release, legal-review draft — see the legal overview page — and have not yet been reviewed by a lawyer qualified in German, Austrian, or EU consumer law.