Factory Solar System Sizing in Malaysia: A Load Profile Guide
Sources reviewed: 17 October 2026. This guide addresses factory rooftop solar planning in Peninsular Malaysia.
The right factory solar system size depends on when the factory uses electricity, the usable roof, the electrical connection and the chosen programme. A monthly bill or roof area alone cannot establish the best capacity. Ask for a comparison of several sizes using the same load data and operating assumptions.
What is a factory load profile?
A load profile records how electricity demand changes over time. For solar planning, it helps the designer compare expected generation with demand during the same intervals, including weekends and production shutdowns.
Two factories with similar monthly consumption may need different designs. A daytime production facility may use much of its solar output immediately. A facility running mainly at night may have less demand while the panels generate. Monthly totals hide that difference.
The Australian Government’s solar guide for businesses similarly highlights the importance of business operating hours and using solar electricity on-site. That is useful planning guidance; Australian rebates and electricity arrangements do not apply to Malaysian projects.
Which data should you prepare for a sizing assessment?
Use this as an enquiry checklist. It is a recommended information pack, not an official application-document list.
| Information | Why it helps |
|---|---|
| Ideally 12 months of electricity bills | Shows seasonal consumption, account details and billed demand. |
| Interval load records, where available | Shows how demand overlaps with expected solar output. |
| Shift times and shutdown calendar | Explains weekends, holidays and unusually quiet periods. |
| Roof plans and building records | Helps establish the space and constraints to investigate. |
| Electrical drawings and supply details | Supports review of the proposed connection. |
| Planned production changes | Separates today’s demand from a future expansion scenario. |
If interval records are unavailable, ask what temporary measurement or other evidence would improve the estimate. Label assumptions clearly until better data is available. A new production line should not be treated as an existing load merely because it appears in an expansion plan.
How does solar self-consumption affect system size?
Direct solar self-consumption is solar electricity used at the premises as it is generated. The self-consumption ratio is that electricity divided by total solar generation over the same period. The examples below assume no storage. For that simplified system, the solar electricity used on-site in an interval cannot exceed either the available solar output or the site’s demand in that interval.
Consider this deliberately simplified example with constant power over one hour:
| Illustrative condition | Electricity over that hour |
|---|---|
| Factory demand of 100 kW | 100 kWh required |
| Solar output of 80 kW | 80 kWh generated and used on-site |
| Remaining grid supply | 20 kWh |
If factory demand falls to 30 kW while potential solar output remains 80 kW, only 30 kWh can be used directly during that hour. The remaining 50 kWh would need permitted export, storage or curtailed production, depending on the actual design. These numbers are arithmetic examples, not a Malaysian yield forecast or an export entitlement.
Ask the designer to repeat this comparison across the available time series. Annual generation divided by annual consumption does not show how much production is usable at the moment it occurs.
Are panel capacity and inverter capacity the same?
No. Panel nameplate capacity is commonly expressed in kWp DC, while inverter output capacity is expressed in kW AC. Ask each proposal to state both, plus estimated annual generation in kWh. These describe different aspects of the system.
The U.S. Department of Energy explains the inverter’s DC-to-AC role in its inverter guide. For your proposal, ask the designer to explain the selected relationship between panel and inverter capacity and any output limitation included in the forecast. Do not compare quotations using an unspecified “kW” label.
Which other limits must the designer check?
Review roof suitability, shading, access, electrical constraints and the applicable programme alongside the load analysis. SEDA’s Solar ATAP information sets out capacity and technical-assessment conditions; a commercial sizing recommendation does not replace programme approval.
Ask for a small, medium and larger option with the same assumptions. Compare upfront cost, on-site use, export or curtailment, operating expenses and downside cases. The largest roof-filling option may not deliver the best financial result for the factory’s operating pattern.
Common sizing questions
Can my electricity bill provide an initial estimate?
Yes, it can support an initial discussion. A firm design needs further site and electrical information, and a defensible self-consumption forecast benefits from interval demand data.
Should I size solar for a future factory expansion?
Ask for separate current-demand and expansion cases, including the expected start date. Compare installing once with a staged approach, and have the designer confirm the practical limits of later expansion.
Plan your factory solar assessment
Share your bills, operating schedule and available drawings with Candela’s Solar EPCC team. Request a capacity comparison with explicit data gaps and assumptions.
Continue with our guides to factory roof suitability, ATAP versus SELCO and industrial solar payback. When quotations arrive, use the EPCC quotation comparison checklist to compare the complete scope.