How we calculate

How do you check voltage?

Open-circuit voltage rises as cells cool. We check Voc_cold = Ns × Voc × [1 + |β| × (25 − Tmin)] against the port’s maximum, the same correction NEC Article 690.7 requires. Above the limit, the verdict is Danger: overvoltage. Separately, Ns × Vmp must reach the port’s minimum or the controller won’t start.

What do you assume when a maker publishes nothing?

• Temperature coefficient: −0.40 %/°C, worse than typical crystalline panels at −0.25 to −0.30, reaching a 1.2× multiplier at −25 °C. Results using it never show as a plain “Works”.
• Hot-weather sag: −0.35 %/°C on Vmp at a 65 °C cell, shown as a caveat.
• Missing limits: an unpublished current limit or unconfirmed connector means Unverified, never a pass.
• Appliance loads: typical values, labelled as such. Enter your nameplate figures for your own number.

How do you handle current over the port limit?

Makers don’t publish how far short-circuit current may exceed a port’s rating. A single string can’t be rewired and MPPT controllers limit their own draw, so one string above the limit shows as clipped power with a caveat. Parallel strings above it are avoidable, so they’re marked over the limit, as is anything above 30 A on 10 AWG cable.

How do you estimate recharge and runtime?

Recharge uses Wh ÷ min(port cap, array watts × 0.70) in peak-sun hours, with city figures from NREL/NLR PVWatts v8 (NSRDB), fixed tilt at latitude, south-facing. Runtime uses Wh × 0.70 to 0.85 ÷ average watts. Surge is checked against the published AC surge rating.

How do specs get in?

A language model transcribes each manufacturer’s page into a strict format, and must supply a verbatim quote for every value. Code then confirms the quote is on the page and checks the physics: Vmp × Imp within 15% of rated watts, Voc above Vmp, Isc above Imp. Anything failing goes to quarantine, and gets no pages.

What are the limits of this tool?

Listings and manufacturers change hardware without notice, and connector fields sometimes rely on secondary sources, which we label. Treat a result as a strong starting point, then check your unit’s label and manual. Multi-port totals follow the station’s published combined limit, but some stations also limit combined current, so check the manual if you’re using several ports.