How we score
Every product on PowerGuide carries a score out of 5 and a band from A to E, styled after the energy-performance bands you already know from an EPC certificate. The score is set by the editor from the same spec table you see on the product page.
What goes into the score
Each category weights the specs that actually decide performance in that category — for a home battery that is usable capacity, round-trip efficiency, cycle life and warranty against price per kWh; for a plug-in solar kit it is real output, MPPT channels, battery pairing and price per watt. Headline marketing numbers that do not survive the datasheet are ignored.
The bands
| A | 4.5 – 5.0 | Best in class. Leads its category on the specs that matter and is priced fairly for them. |
| B | 4.0 – 4.4 | Strong choice. Competitive specs with minor trade-offs. |
| C | 3.5 – 3.9 | Solid but situational. Right for some setups; beaten on value elsewhere. |
| D | 3.0 – 3.4 | Compromised. Notable gaps in specs, warranty or value. |
| E | below 3.0 | Hard to recommend at current pricing. |
What does not go into it
- Manufacturers cannot pay for a score, see it early, or change it.
- Affiliate commissions have no bearing on scores or rankings. Some links earn us a commission; the score is set before any link is added.
- We do not use manufacturer review programmes or sponsored samples.
When scores change
Scores are revisited when a product's price moves materially, a firmware or spec revision lands, or better rivals ship. The "prices checked" date on each comparison table tells you when the numbers were last confirmed.