Factories with solar can add EV charging in 3 configurations: (1) Rooftop Solar + Wall Charger with 4-6 year payback, (2) Solar Carport + Charger with 6-9 year payback, (3) Solar + BESS + DC Fast Charging for 24/7 charging. The critical factor is demand charge, which can increase 26,600-42,000 THB/month without smart load management. BOI A2 category offers 8-year CIT exemption to shorten payback.
ERC issued a new checklist (02/10/26) for the EV-station electricity-sale licence — what a factory opening charging for fleets or staff must prepare
The ERC Office's Energy Business Licensing Division published an updated (02/10/26) "Checklist of documents for the electricity-sale licence for EV-station business" (row 12 on the ERC application-forms page). It groups the documents into 10 items — the E-License application letter, charger spec and Single Line Diagram, engineer certification, power-supply plan, the tariff the station buys at, and a monthly kWh sales plan — and states that an incomplete file is returned without being accepted. For a factory that already has solar and is about to open fee-based charging, this is the document list to prepare alongside the electrical design.
- The checklist's scope is "electricity-sale business (EV station)" — charging services to "direct customers" (a specific contract with a company, e.g. a fleet operator or taxi cooperative) or "public customers" (anyone), as defined in item 9. ERC also runs a separate "exemption notification" track for EV charging-station projects that are exempt from the electricity-sale licence (ERC Office announcement on its exemption page). Confirm with ERC which track your project falls under before opening.
- Item 7, power-supply plan: if the EV station is fed from the existing factory building that already buys from the utility, a copy of the building's existing supply contract is accepted — but an engineer must confirm that EV load plus building load does not exceed the transformer rating and does not endanger the installed circuits. In every case the connected transformer must be no smaller than the total EV charger capacity.
- Item 8, the tariff the station buys at: you must state which tariff feeds the station (e.g. Low Priority or TOU) and attach the utility's notice. The checklist spells out the utility's conditions for the Low Priority rate — power bought from the utility, a new meter installed specifically for the EV station, and service to the general public. A charging point behind the factory's existing meter that serves only staff or a fleet does not meet those conditions and pays the factory's own tariff.
- Closing note on the checklist: the applicant must submit every document complete and correct; otherwise staff return the file without accepting the application. The number of chargers and total capacity (the checklist's example: 5 units of 200 kVA = 1,000 kVA) must match across the cover letter, the E-License form, the SLD and the spec table, and every engineering page must be signed by a licensed electrical engineer.
ERC's 10-item checklist → how a factory that already has solar should prepare (CapSolar's reading)
| Checklist item | What ERC asks for (02/10/26 edition) | How the factory prepares |
|---|---|---|
| Item 1 — Application + E-License | The cover letter must name the EV station (e.g. after the sub-district or site), the number of chargers and their total capacity; the figures must match the E-License form, the SLD and the spec table. | Freeze the charger plan before filing (use the sizing section below) and carry one set of numbers through all three documents — changing later means re-issuing every one. |
| Item 3 — Spec + SLD + layout | Manufacturer spec; an SLD showing each charger's kW (DC/AC) and any Power Unit Control, traced from the supply source through the MDB to the transformer size; a site layout (map showing the road or neighbouring premises) and, for indoor stations, a floor plan per floor. | If solar is on site, have the same SLD show the PV inverter tie-in and the EMS as well (CapSolar's recommendation so the reviewer sees the full load/source picture) — not a checklist requirement. |
| Items 6 + 7 — Engineer certification + power-supply plan | A licensed electrical engineer signs every spec/drawing page; if fed from the existing building, the building's supply contract plus the engineer's confirmation that total load stays within the transformer; in all cases the transformer must not be smaller than the total charger capacity. | Worked example (CapSolar's illustrative numbers): a 1,000 kVA transformer with a 700 kVA factory peak; adding 5 x 200 kVA DC chargers (the checklist's own 1,000 kVA example) pushes total load past the transformer. Options: fewer/smaller chargers, an EMS that caps charging power dynamically, or a transformer upgrade — and whichever you choose, the transformer still may not be smaller than the total charger capacity. |
| Item 8 — Tariff the station buys at | State the tariff (Low Priority / TOU / a private producer's rate) and attach the notice; Low Priority requires buying from the utility + a new EV-station-only meter + serving public customers. | Make the business decision first: a charging point behind the factory's existing meter pays the factory's TOU rate — so charge during solar hours or off-peak and check the demand-charge impact in the section above; the Low Priority rate means accepting a separate meter and public access, which is a different business model. |
| Items 9 + 10 — kWh sales plan + customer contracts | A monthly kWh sales forecast for the first year and the next (12 months), split direct vs public customers (public count stated as "unspecified"), used to compute the annual fee; direct customers need a supply contract stating the price in baht (Ft may be itemised); public customers need a letter stating the rate. | Use the rules of thumb in the sizing section (20-40 kWh/day per employee car; fleet = battery capacity x trips/day x efficiency) x working days to build the 12-month table, then set the baht/kWh you will charge (see the FAQ below on charging employees). |
Next step: confirm with ERC (hotline 1204 or the E-License system) whether your project needs the electricity-sale licence or falls under exemption notification, then build the file to the checklist — CapSolar can prepare the SLD, spec table and kWh sales plan consistent with the factory's existing solar system.
Why Factories Are Combining Solar and EV Charging in 2026
Thailand sold 120,301 BEVs in 2025 (+80% YoY), and January 2026 hit a record 48% EV penetration among new registrations. Factory employees increasingly need workplace charging, while many factories are electrifying forklifts and delivery fleets. Solar + EV charging answers both energy cost reduction and fuel savings in one capex decision.
EV battery manufacturing plants have high continuous power demand — solar for EV battery manufacturing is another model worth exploring
Thailand EV Adoption Acceleration
120,301 BEV sold in 2025 (+80%), 48% penetration in Jan 2026. Industrial fleet procurement of EVs is accelerating.
Employee Workplace Charging Demand
Employees with EVs need to charge during 8-hour shifts. A single shift on a 7 kW AC charger delivers a full charge -- a compelling benefit for talent attraction.
Fleet Electrification
Electric forklifts, delivery trucks, company cars -- all need factory charging. Solar reduces charging cost versus grid-only power.
Stackable BOI Incentives
Solar qualifies for BOI A2 (8-year CIT exemption + machinery duty waiver). EV charger installation has its own BOI promotion window 2026-2027. Both can stack in one project.
ESG / RE100 — Two Goals, One Budget
Solar cuts Scope 2 (electricity), EV fleet cuts Scope 1 (fuel). Combined in one project = dual decarbonization. Addresses CBAM compliance + green supply chain requirements.
3 Configuration Models for Factory Solar + EV Charging
Model 1 — Rooftop Solar + Wall Chargers (Most Common)
Uses existing rooftop solar. Surplus power beyond factory load feeds AC wall chargers (7-22 kW). Lowest capex. Ideal for employee charging -- an 8-hour shift fully charges on 7 kW AC.
Model 2 — Solar Carport + Integrated Chargers
Parking structure with solar panels on top, chargers underneath. 20-75% higher capex per watt than rooftop, but dual function: shade + power. Ideal when rooftop space is full or for new factory builds.
Model 3 — Solar + BESS + DC Fast Charging (Premium)
BESS buffers solar for evening/night charging. DC fast chargers (50-180 kW) for fleet vehicles needing rapid turnaround. Highest capex but enables 24/7 solar-powered charging without grid dependency.
Petrol stations are transitioning to EV — solar for petrol stations & EV hubs
| Feature | Rooftop + Wall | Solar Carport | Solar+BESS+DC |
|---|---|---|---|
| Capex | Lowest | Medium-High | Highest |
| Payback | 4-6 years | 6-9 years | 8-12 years |
| Charging Hours | Daytime (solar hours) | Daytime (solar hours) | 24/7 |
| Best For | Employee charging, day shift | Full rooftop / new builds | 24/7 fleet / logistics hub |
| Extra Space Needed? | No (existing roof) | Existing parking area | Parking + BESS footprint |
Demand Charge Impact — The Hidden Cost Factory Owners Must Calculate
Adding EV chargers to a factory can spike peak demand, significantly increasing demand charges. PEA charges 74.14-210.00 THB/kW-month depending on voltage tier.
Example: Running 4x 50 kW DC Fast Chargers Simultaneously
4 x 50 kW = +200 kW peak demand = up to ~42,000 THB/month extra demand charge (at <12 kV, 210 THB/kW) or ~26,600 THB/month (at 12-24 kV, 132.93 THB/kW)
Factory Solar Battery (BESS)
Sizing Your Factory Solar + EV System
EV Charger Types and Specifications for Factory Use
| Type | Power | Charge Time (60 kWh) | Best For | Approx. Cost (THB) |
|---|---|---|---|---|
| AC Wall Box (Level 2) | 7-22 kW | 3-8 hours | Employee parking, overnight fleet | 25,000-80,000 |
| DC Fast Charger | 50-60 kW | 1-1.5 hours | Fleet turnaround, visitor charging | 500,000-1,200,000 |
| DC Ultra-Fast | 120-180 kW | 20-35 min | Heavy fleet, logistics hub | 1,500,000-3,000,000 |
Thai charging standards: CCS2 (dominant DC) and Type 2 AC (most EVs)
Car wash centers are adding EV chargers as a value-add service — customers charge while waiting: solar for car wash & detailing centers with EV charging
BOI and Government Incentives for Solar + EV Charging
ROI Analysis — When Does Solar + EV Make Financial Sense?
Base Case: 500 kWp Rooftop + 20 AC Chargers
Carport Case: 200 kWp Solar Carport + 10 Chargers
Higher capex but land-neutral (existing parking). Payback 6-9 years including carport structure cost.
Key sensitivity: demand charge impact can add or subtract 1-2 years from payback depending on load management.
5 Steps from Decision to Charging
Energy Audit — Assess load profile, solar capacity, parking layout
Review factory load profile, existing/expandable solar capacity, and parking layout. Identify surplus solar windows for charging.
Charger Selection — Match charger types to use cases
Select charger types based on use cases: AC wall box for employees, DC fast for fleet and visitors. Plan quantity and placement.
Electrical Infrastructure — Panel upgrade, EV circuit, smart metering
Upgrade electrical panel, install dedicated EV circuit, add smart metering for cost allocation and demand charge management.
Solar Integration — Inverter compatibility, EMS for solar priority
Verify inverter supports additional load. Install Energy Management System (EMS) so chargers prioritize solar over grid.
Commissioning — App setup, access control, billing
Set up charger management platform, employee/visitor access control, and service billing system (if applicable).
Ready to Combine Solar + EV Charging at Your Factory?
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