The honest energy reference for households.
Watt Guide exists to answer one boring, decisive question: what does this actually cost me? No installer pitch, no affiliate-ranking trick, no inflated lifetime-savings hype. Just the math, sourced from public datasets and updated when those datasets change.
Numbers over opinions
Every claim about cost or savings is tied to a public dataset — EIA, Ofgem, NREL, Eurostat, CRU, AER — or a manufacturer spec sheet. If we can't source it, we don't print it.
Compiled and cross-checked
Figures are compiled from public datasets (EIA, NREL, DSIRE, ENERGY STAR) and cross-checked across sources. Where a figure relies on someone else's measurement, we say so rather than implying we tested it. See our full methodology.
Quarterly tariff refresh
Country and state-average rates refreshed every quarter. Every guide reviewed at least every 6 months. The publish date is the date the article was last verified.
What we never do
No pay-for-placement. No affiliate-pressure rankings. No "lifetime savings" assuming 8% utility inflation. No vendor screenshots passed off as test results. Every guide is written and reviewed by a named person — Bruno de Madrazo — reachable at our contact form.
Where the numbers come from
Every cost in the site traces back to one of these sources. Each pillar article cites them inline.
| Source | What we use it for |
|---|---|
| US EIA | US state-level residential electricity + natural gas prices, fuel inflation history. |
| NREL PVWatts | Solar PV annual production by location, orientation and tilt. |
| DSIRE | State, utility and local incentives for solar, heat pump, EV and storage. |
| EnergySage | Quoted $/W medians for residential solar by state, refreshed quarterly. |
| LBNL Tracking the Sun | Long-term residential PV pricing trend, installer-tier breakdown. |
| Ofgem + Energy Saving Trust | UK retail electricity prices, price cap data, appliance benchmarks. |
| EPA fueleconomy.gov | EV efficiency (kWh/mi), gasoline MPG benchmarks. |
| ENERGY STAR | Heat pump HSPF/SEER, refrigerator kWh/yr, washer/dryer ratings. |
| Eurostat + CRU + AER | Residential electricity prices for EU, Ireland and Australia. |
How Watt Guide pays for itself
Watt Guide is funded by two streams, in this order of importance:
- Contextual ads served by Google AdSense. Ads are auctioned in real time based on page content. We have no relationship with the advertisers.
- Affiliate links to major retailers on a small subset of articles. When present they are clearly labelled and never determine which products are recommended.
Nothing on this site is sponsored content. Nothing is paid placement. When you read a comparison ranking, the order reflects our reading of the public testing data and published efficiency ratings — nothing else.
Get in touch
- Corrections / topic requests: Contact form.
- Press & data partnerships: mention "Press" in the subject on the same form.
- Privacy / DSAR requests: see Privacy policy.
Legal notice
- Site operator: Bruno de Madrazo (Watt Guide).
- Domain: watt-guide.com
- Activity: independent online publication on residential electricity costs and home energy systems.
- Disclaimer: educational content. Not a substitute for a licensed electrician, energy auditor, solar installer or utility representative. Verify any cost with your utility before financial decisions.
- Intellectual property: original text, graphics and code © Watt Guide. Excerpts may be quoted with attribution and link.