Three-Phase Solar: Check Inverter Limits Before Changing Supply
Decision details
Fits if: Homeowners comparing a solar proposal with existing supply or considering separate connection work.
Main drawback: Connection-change cost and timing remain unknown until the relevant parties provide written scope.
Compare: phase on bill/switchboard, inverter kWac, panel kWp, CCC, connection-work scope, upfront charges, any deposit/refund terms and load profile.
In this guide
Check phase and inverter capacity
Check the phase on the electricity bill and main switchboard. Ask the design to state panel capacity in kWp and inverter output in kWac separately. Usual domestic limits are 5 kWac single-phase and 15 kWac three-phase; panel kWp is not the inverter limit [source] [source]. No monthly bill amount establishes that supply must be changed.
Compare the system design before paying for a phase change
For a single-phase home, first ask the installer to show an option within the usual 5 kWac limit and the proposed three-phase option, listing panel kWp and inverter kWac separately. If the single-phase design suits the site and project, compare its full price without treating phase-change work as a given. If a larger option is proposed, ask why that design needs a different phase, which CCC/application route applies, and what the utility confirms in writing. Compare each option’s full cost—system price plus applicable premises/connection work and utility charges, including the status of any deposit—because higher panel kWp alone does not establish better value or fit.
Supply condition and next check
| Condition | What to confirm |
|---|---|
| Single-phase supply | Inverter kWac output and current domestic limit |
| Three-phase supply | Inverter kWac output, design and site condition |
| Proposal above domestic limit | Whether CCC applies, fee, applicant and utility decision; approval is not guaranteed |
| Supply-phase work may be needed | Ask first whether a change is needed for this design; if so, request itemized meter/panel, cable/switchboard work and utility charges where applicable, plus any deposit and written refund terms |
Domestic proposals above the usual limit are subject to a RM1,000 Connection Confirmation Check (CCC). CCC is not an automatic prohibition, does not guarantee approval and does not mean a supply upgrade is required [source]. Identify the applicable ATAP application fee and contract stamp duty in current paperwork [source] [source].
Quote worksheet: compare phase and itemized scope
Fill this from the dated design and quotation. Ask for models, outputs and charges separately: panel kWp is not inverter kWac, and connection work is not necessarily included.
| Item | What to request | Record to keep |
|---|---|---|
| Supply phase | Phase checked at the premises; do not infer it from the bill amount | Bill/switchboard record and check date |
| Modules and inverter | Module model/count and total kWp; inverter model/output kWac on a separate line | Written design |
| Domestic CCC | Above 5 kWac single-phase or 15 three-phase, ask whether CCC applies, who applies, status and RM1,000 fee; approval is not guaranteed [source] [source] | Written applicant/utility response |
| Connection, meter and activation | Whether utility meter/inspection work applies, who arranges it, prerequisites and estimated milestones; separate connection/phase work and charges from system price | Dated written provider/utility response; mark unconfirmed if absent |
Compare the design beside the quotation. Mark missing items unconfirmed and request written answers before comparing totals.
If the roof or meter is shared
For a condo or strata building, do not assume one unit can decide about a roof or meter held in common. Confirm roof status, decision authority, JMB/MC decision, the meter that will use the energy, common-area loads, maintenance access and contract party. Obtain the approval route and responsibilities in writing; this page does not establish rights or approval for a particular building.
If you rent the home
If you rent, take the proposal to the landlord and electricity account holder before committing. Confirm each point for your premises; this checklist does not determine rights or approval.
| Item | Question to verify in writing |
|---|---|
| Ownership | Who owns the roof and the equipment to be installed, including panels, inverter and wiring? |
| Consent and shared areas | Is written consent needed from the landlord or account holder, and is a JMB/MC or other decision needed for the roof or shared property? |
| Application and work | Who will sign the contract and handle the application, installer and utility arrangements; what site checks or conditions still need confirmation? |
| End of tenancy | If the tenancy ends, who pays to keep, move or remove the equipment, and restore the roof or premises? |
Ask the provider, landlord, account holder and relevant parties to state the applicable responsibilities and costs before you agree.
For non-domestic premises
Do not apply domestic limits to commercial premises. Gather the bill with kWh and MD, voltage class, operating schedule, location and connection/export information. Ask for a study tied to MD and network conditions; the recorded non-domestic ATAP limit is up to 100% of MD and 1,000 kW maximum, subject to network assessment [source]. Home prices or small-system advertisements are not large-project rates.
Check the contract and applicable operating term in the current application documents [source]. Do not commit to a phase change until the relevant party gives written cost, scope and schedule.
Frequently asked questions
Does a high electricity bill mean my home must change to three-phase supply?
No verified monthly bill-amount threshold is established here. Check the phase on the bill and switchboard, then compare the proposed inverter output with the current limit. An RM bill amount alone does not determine a phase change.
What are the usual domestic Solar ATAP limits?
Usual limits are 5 kWac for single-phase supply and 15 kWac for three-phase. They refer to inverter AC output, not panel DC capacity in kWp [source] [source].
Is a system above the limit prohibited or does it require a phase upgrade?
Domestic proposals above a limit are subject to a CCC with a RM1,000 fee; this is not an automatic prohibition or approval guarantee. It also does not prove that a phase upgrade is required. Ask the applicant and utility to confirm the route in writing [source].
Are phase-change cost and timing included in a solar quote?
Do not assume so. No standard total is established here, and historical forum amounts are not current quotes. First ask whether a phase change is actually needed for the proposed design and applicable route. If it is, request separate itemized scope from the installer/electrician and utility, including meter, panel, cable or switchboard work and charges only where applicable, plus any deposit and written refund conditions. Confirm who pays each amount, what is due upfront, what the solar package already includes and the expected schedule [source] [source].
After the panels are installed, when is the system activated and must the meter be changed?
The available information does not establish that a meter change or utility visit is required, or how long either step takes. Ask the provider and utility to confirm the applicable meter/inspection steps, responsible party, prerequisites, charges and estimated schedule in writing; mark anything still unconfirmed.
How should a condo or strata owner begin?
Confirm roof status and decision authority, obtain the JMB/MC decision, identify the meter receiving the energy and shared loads, then request written technical and approval checks. This page does not establish approval or benefit-sharing terms for a particular building.
Can solar energy be shared across units or is a rebate available?
Do not assume energy can be allocated across meters or that a rebate is available. Verify the meters, ownership, programme and current terms, then obtain the allocation method and approvals in writing before modelling benefits.
Does the 15 kWac domestic limit determine a commercial site's system?
Do not apply domestic limits to non-domestic premises. Ask the applicant to verify MD, voltage class, operating profile, export and network conditions; the recorded non-domestic ATAP limit is up to 100% of MD and 1,000 kW maximum, subject to network assessment [source].
Can a home-system price be used to estimate a large-premises project?
No. Request a project quotation that states capacity, connection, site works, MD/usage profile and energy assumptions; a home-system advertisement does not price a commercial project.
Should a large premises automatically add a battery?
No general choice follows from system size or phase alone. Ask for backup or operating needs, usage profile, cost and battery terms as a separate proposal; this page does not establish battery economics.
What information should I prepare for a large-premises proposal?
Provide bill kWh and MD, voltage class, operating schedule, location, roof/site details, and connection and export conditions so the provider can state its assumptions and scope.