Every calculator here is built to the same rule: the formula is shown, the constants are named, and the limits are stated. Nothing is a black box. Below is what comes next, and the reasoning behind the order.
Calculations split into two kinds. Physics-based ones — voltage drop, string voltage, energy yield, conductor resistance — follow from physical constants and hold everywhere in the world. Code-based ones — ampacity tables, overcurrent device sizing, derating by installation method — are a lookup against a specific standard, and the same cable gets a different answer under NEC and under IEC.
So the physics comes first. It is universally useful, and it cannot be wrong because of a jurisdiction. The code tables come later and later they will be labelled by code, with the edition stated — at which point they become the part of this site that is genuinely hard to copy.
| Calculator | What it answers |
|---|---|
| Cable Voltage Drop | How many volts do I lose, and what size fixes it |
| Solar String Configurator | How many modules per string before the inverter window breaks |
| Battery Bank Sizer | Nameplate kWh from daily load, autonomy and chemistry |
| PV Energy Yield | Annual kWh from location, tilt and azimuth |
| Conductor Size Converter | AWG ↔ kcmil ↔ mm², with resistance at temperature |
| Power Loss & Cost | What the cable losses cost per year |
| Calculator | Status | Why it is on the list |
|---|---|---|
| Inverter sizing & DC/AC ratio | Planned | The question right after string sizing; pairs naturally with what is live |
| Fault current / short circuit | Planned | Needed for device ratings, pure impedance math |
| Earthing / grounding resistance | Planned | Geometry and soil resistivity, code-independent |
| Conduit & tray fill | Planned | Area arithmetic, universally asked |
| Transformer sizing & losses | Planned | Standard nameplate math, no code dependency |
| Solar payback & LCOE | Planned | Extends the energy yield tool into money terms |
| Backup runtime & load shedding | Planned | The other half of battery sizing |
| Reference | Status | Note |
|---|---|---|
| Conductor ampacity tables (NEC / IEC) | Later | Published per code with edition; the moat |
| Overcurrent device & OCPD sizing | Later | Follows the ampacity tables |
| Conduit derating & bundling factors | Later | Installation-method dependent |
| Voltage drop limits by jurisdiction | Later | Accepted percentages differ by code and utility |
The list above is a guess about what is useful. A request that names a real job — the calculation you needed on a bid last week and could not find — jumps the queue. Email gridcalcs-good@outlook.com with the calculation and the decision it supports. Same address for numbers that look wrong; every calculator here shows its formula precisely so that mistakes are catchable.