Can solar work normally alongside EAF furnaces? Will there be arc flash issues?

Yes, but requires proper design. Standard IEC 62116 (Anti-Islanding) inverters automatically trip on grid fault or arc flash and reconnect after grid stabilizes within 5 minutes. The real concern is voltage flicker from EAF causing nuisance tripping. Recommend inverters tested for Ride-Through per EN 50549 and conducting a Power Quality Study beforehand.

Is solar still worthwhile for 3-shift continuous operation factories?

Worthwhile, but ROI is longer than 1-2 shift factories because solar covers only daytime (25-40% of total electricity costs). However, for high demand-charge factories, combining solar + BESS for daytime peak shaving is still very valuable since demand charges can be 30-40% of the bill. Combined ROI is 5-7 years for 3-shift (vs. 4-5 years for 2-shift).

How is demand charge calculated? Can solar + BESS really reduce it?

Demand Charge = Highest 15-minute Peak Demand (kW) per month × demand rate (~220-320 THB/kW/month). Example: 5,000 kW peak = 5,000 × 250 = 1.25M THB/month. Solar + BESS reduces this by BESS supplying power during Melting Phase → Peak Demand drops to 3,800 kW → Demand Charge reduced to 950,000 THB. Saving 300,000 THB/month.

Steel factories often have low power factor. Can solar help fix this?

Modern solar inverters can inject reactive power (Q), improving power factor at the point of connection. However, for factories with EAF/Induction Furnaces at very low PF (0.75-0.85), a 1-3 MWp inverter provides only partial correction — additional Capacitor Banks or Static VAr Compensators (SVC) are still needed. Improving PF to 0.9-0.95 saves 200,000-500,000 THB/month in kVar penalties.

Can steel factories apply for BOI? Any special conditions for the steel industry?

BOI incentives for solar (Activity Type 7.2.3 — Renewable Energy Production) apply to steel factories as well. Royal Decree 805 allows 1.5x solar depreciation deduction reducing CIT. However, some steel types (long products like rebar) may be subject to anti-dumping duty restrictions, and BOI may not grant import duty exemptions for certain steel inputs. Consult BOI and tax advisors directly.

How will EU CBAM affect steel exports from Thailand? Can solar help?

CBAM (Carbon Border Adjustment Mechanism) began levying actual carbon costs on EU-exported steel from 2026, calculated from Embedded Carbon in the production process — especially the electricity emission factor. On-site solar significantly reduces this emission factor. Factories using solar for 30% of total electricity can reduce embedded carbon in steel by ~15%, which counts as verifiable carbon reduction for EU CBAM reporting.

What services does CapSolar provide for steel and metal factories?

CapSolar provides full-scope solar services for steel and metal factories: (1) Power Quality Study + Harmonic Analysis before design, (2) Inverter selection suited to high-harmonic grid conditions, (3) Solar + BESS design for peak shaving to reduce demand charges, (4) PMS integration with EAF/Induction Furnace control systems, (5) Both EPC (purchase system) and PPA (zero investment, pay only for actual solar used) models. Free consultation by engineers experienced in Industrial Power.

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Industry

Solar for Steel & Metal Factories

Cut EAF, Rolling Mill & Heat Treatment Electricity 25-40% with Solar

Thailand has 3,000+ steel and metal factories. Electric Arc Furnace (EAF) consumes 400-600 kWh/ton with high demand charges from arc startup — solar combined with peak shaving is the answer for this industry.

Steel and metal factories in Thailand are among the heaviest electricity users. Electric Arc Furnace (EAF) consumes 400-600 kWh per ton of steel, with rolling mills and heat treatment adding 50-150 kWh/ton. Electricity costs represent 20-35% of total production cost. Solar doesn't just reduce energy charges — combined with peak shaving, it also cuts demand charges from arc demand spikes by 15-25%. A 1-10 MWp rooftop system on a typical steel factory saves 2-15M THB/year with ROI in 4-6 years, and addresses CBAM requirements for EU steel exports.

Electricity Costs in Thailand's Steel & Metal Industry

Thailand's steel and metal industry has 3,000+ factories concentrated in Rayong, Samut Prakan, Chonburi, and Saraburi. Four main electricity-intensive processes: Electric Arc Furnace (EAF) for secondary steel, Induction Furnace for cast iron, Rolling Mill for steel forming, and Heat Treatment for hardening and annealing.

Electricity consumption by process: EAF uses 400-600 kWh/ton crude steel, Induction Furnace 550-700 kWh/ton, Rolling Mill adds 50-100 kWh/ton, Heat Treatment adds 30-80 kWh/ton, and secondary processes (galvanizing, pickling) use 20-50 kWh/ton. A mid-size steel plant (50,000 tons/year) pays 80-200M THB/year in electricity.

Steel factory electricity has 3 cost components: (1) Energy Charge per TOU/TOD — daytime On-Peak is 2.5-3x more expensive than Off-Peak night, (2) Demand Charge based on highest 15-minute kW reading — EAF arc startup creates violent demand spikes, with demand charges representing 30-40% of total electricity bills, (3) Ft and AECO surcharges fluctuating with global fossil fuel prices.

Read TOU/TOD & Demand Charge Guide

Challenges: Arc Furnace Demand Spikes, Power Quality & 3-Shift Continuous Operation

Challenge 1 — EAF Demand Spikes: EAF operates in heat cycles of 45-90 minutes per heat. Each cycle has a Melting Phase drawing 80-120% of rated power for 20-40 minutes, then dropping during the Refining Phase. This creates steep demand fluctuations with Peak Demand (15-min reading) 40-70% above average demand.

Challenge 2 — Power Quality & Harmonics: EAF and Induction Furnaces are significant harmonic sources. EAF creates voltage flicker and THD of 15-25%, while Induction Furnaces generate 3rd, 5th, 7th, 11th, 13th harmonics from power electronics. VFDs controlling rolling mills add further harmonics. If solar inverters are not designed for high-harmonic grids, resonance can cause inverter tripping or damage.

Challenge 3 — 3-Shift Continuous Operation: Most large steel factories run 24/7 in 3 shifts to justify furnace and rolling line investment given their long warm-up times. Day shift (07:00-22:00) vs night shift (22:00-07:00) electricity split is typically 50:50 to 60:40. Solar therefore addresses only 25-40% of total electricity costs, compared to 35-50% for 1-2 shift factories.

Solar + Peak Shaving: Reducing EAF Arc Spike Demand Charges

Demand Charge is the biggest pain point for steel factories. Solar alone does not directly reduce demand charges because demand is measured as the highest 15-minute kW reading — if EAF fires an arc precisely when solar peaks, demand is still high. The effective approach is Solar + BESS working together: BESS supplies power during peak Melting Phase instead of the grid, reducing the peak demand measured at the meter.

Three-layer strategy for steel factories: (1) Solar creates Base Offset reducing daytime energy charges by 25-40%, (2) BESS sized 500 kWh-2 MWh performs Active Demand Capping — setting threshold so demand stays below contracted level, (3) PMS instructs EAF to stagger arc timing so multiple furnaces don't arc simultaneously. Combined effect: 28-42% electricity bill reduction.

Real-world example: 2-furnace EAF plant (40-ton/furnace), 8,000 kW contract demand, 12M THB/month electricity. Installed 3 MWp solar + 1 MWh BESS + PMS Arc Stagger → Peak Demand drops 8,000 kW to 6,200 kW → saves 4.3M THB/year in demand charges + 3.2M THB/year in energy charges. Total saving ~7.5M THB/year, ROI ~4.8 years.

Read Factory Peak Shaving + BESS Guide

Steel & Metal Factory Solar System Sizing — 3 Tiers

Solar sizing for steel/metal factories must consider: peak demand (kW), daytime vs nighttime electricity split, available roof area (clearing space around exhaust pipes, cooling towers, and fume extraction systems), and Grid Code requirements set by PEA/MEA for large systems.

Factory Size	Peak Demand	Recommended Solar	Annual Saving
Small metal workshop	200-500 kW peak	150-400 kWp	0.5-1.5M THB/yr
Medium steel plant (Induction/Rolling)	1-3 MW peak	1-2.5 MWp	3-8M THB/yr
Large integrated steel plant (EAF + Rolling)	5-15 MW peak	5-10 MWp	10-25M THB/yr

Note: figures reference 2026 TOU tariffs for >500 kW consumers. Actual savings depend on load factor, production shifts, and available roof area.

See Grid Interconnection for Large Systems

Power Quality: Harmonics from VFD/Inverter Interaction & IEEE 519 Compliance

Steel factories have the most complex power quality environment of any industry. Main harmonic sources: EAF (arc flash — flicker + interharmonics), Induction Furnace (medium frequency 150-10,000 Hz → harmonics up to 25th), Rolling Mill VFDs (6-pulse → 5th/7th, 12-pulse → 11th/13th), and other drives/UPS. Adding solar inverters to an already high-harmonic system risks resonance between inverter filters and existing capacitor banks.

IEEE 519 Standard sets THD (Total Harmonic Distortion) limits at the Point of Common Coupling (PCC): systems <69 kV require THD < 5% and Individual Harmonic < 3%. For steel factories needing IEEE 519 compliance, adding solar requires a Power Quality Study before inverter selection and appropriate harmonic filter specification.

Best practices for steel factories: (1) Select grid-tie inverters with active anti-islanding + low harmonic output (THD <3% at rated load), (2) Conduct Harmonic Flow Study including EAF/Induction/VFD loads before purchasing inverters, (3) Install Active Harmonic Filter (AHF) at main bus if total THD exceeds 4%, (4) Design inverter LCL filter so resonant frequency doesn't match EAF harmonic frequencies.

Read Power Factor Correction for Factories See Factory Solar Fire Safety Guide

FAQ

Solar + ESG/CBAM — Reduce carbon & save tax, critical for EU steel exports

Complete Demand Charge + TOU/TOD Guide — Understand Steel Factory Electricity Bills

Cut EAF & Rolling Mill Electricity with Solar — Free Consultation

CapSolar engineers specializing in Industrial Power Quality design solar systems specifically for steel and metal factories. We analyze harmonics, calculate peak shaving savings, and compare EPC vs PPA options.

Free Consultation — Steel & Metal Factory Solar