SolarKrasibCalculate

Single-phase vs three-phase electricity

Phase count concerns supply and load distribution, not your electricity price plan.

Edited by SolarKrasibUpdated 22 September 2026Read4 min

The answer first

Single-phase and three-phase describe electrical supply. Normal and TOU describe billing methods. Select them separately: changing to three-phase alone does not automatically reduce the price per kWh.

Start with your meter and household loads

Ask an installer to check meter rating, main cable, breakers and per-phase loads before selecting an inverter. Three-phase homes need load-balance and connection checks. Do not choose inverter capacity based only on calculated savings.

Do not alter the supply just to fit a package

If a proposal changes phase configuration, request an electrical design, engineering rationale, equipment list and costs, and confirm with the utility. This website models aggregate energy at the meter, not every device’s phase-flow or cross-phase compensation limitations.

Questions to discuss

Does the inverter support the existing supply? Must the meter or distribution board change? Does the design satisfy local connection requirements? Which circuits remain powered during an outage?

Supporting sources

  1. PEA — Electricity tariff effective September 2026 ↗
  2. PEA — Solar rooftop standards and safety ↗
  3. PEA — Generation system connection application ↗
  4. MEA — MyEnergy and electricity purchase announcements ↗

General information for questions and preliminary estimates. Site and contract conditions need individual verification. International sources explain principles, not Thai law.

Try this in the calculator