3.1 First distinguish between Schedule 2 and Schedule 3, otherwise all calculations may be wrong.
3.1 First distinguish between Schedule 2 and Schedule 3, otherwise all calculations may be wrong.
The first step in a small commercial project is not to talk about component brands, but to determine what type of electricity price structure the customer belongs to. According to the PEA English electricity price manual,Schedule 2Suitable for general business/service users andThe 15-minute average combined demand is less than 30 kWsituation;Schedule 3then applies to15-minute average combined demand ranges from 30 kW to less than 1,000 kW, medium-sized general service users whose average electricity consumption in the last 3 months does not exceed 250,000 kWh/month.
This line of demarcation is very important, because it determines whether you are dealing with customers who are “mainly paying for energy and electricity bills” or customers who have a dual structure of “energy + demand”. The real complexity of many small commercial projects is not in the installation itself, but in the fact that if you don’t even understand whether the customer belongs to Schedule 2 or Schedule 3, it will be easy to distort the savings and payback period later.
Therefore, new employees must make a hard move: after getting the bill, first check the user category, whether there is demand charge (Demand Charge), what is the maximum 15-minute demand, and whether there is a TOU. Don’t rush to arrange the plan, first determine the bill structure.
| category | official threshold | Billing highlights | Training significance |
|---|---|---|---|
| Schedule 2 | Comprehensive demand in 15 minutes < 30 kW | Mainly based on energy and electricity charges | Closer to household use, but still depends on business hours and TOU |
| Schedule 3 | The comprehensive demand in 15 minutes is 30 kW - < 1,000 kW, and the average power consumption in the past three months is ≤ 250,000 kWh/month | Demand + Electricity | Demand charges and minimum charges must be explained |
| Schedule 4/5 or above | Larger loads or specific industries | more complex | The current stage can be used as an advanced project, and it is not suitable for users to do it with ideas. |
- Official[01] PEA Electricity Tariffs (May 2023 onward) PDF: Clearly list the applicable conditions for Schedule 2 and Schedule 3.
3.2 Small commercial use not only looks at kWh, but also looks at 15-minute demand and minimum demand charges
3.2 Small commercial use not only looks at kWh, but also looks at 15-minute demand and minimum demand charges
The reason why many small commercial proposals fail is not that the system does not generate enough power, but that the demand for electricity is not explained at all during the proposal. For Schedule 3 and above users, the bill is not simply "how much does it cost per kilowatt hour", but includes both demand charge (Demand Charge) and energy charge (Energy Charge). Rooftop photovoltaics can significantly reduce electricity purchases during the day, but the improvement in demand costs is often not as great as many salespeople imagine.
The reason is simple: demand is usually determined by the maximum average load within a certain 15-minute window. If the load peak of the project occurs during early morning start-up, cloudy days, short-term impacts, or just exceeds the instantaneous coverage capacity of photovoltaics, then even if the annual power generation of the system is good, the demand electricity bill may not drop significantly. This needs to be made clear, otherwise sales will over-promise.
More importantly, the PEA manual also statesMinimum demand chargeRules: The TOU rates of Schedule 3, 4, 5, 6, and 7 all have the requirement that "the minimum charge shall not be less than 70% of the maximum demand charge in the past 12 months." In other words, even if a customer's load drops a lot in a certain month, they may not be able to reduce their demand bill to zero. If this point is not made clear, small commercial ROI calculations can easily be overly optimistic.
Demand Charge: Charges based on maximum demand.
Minimum Charge 70%: The minimum demand charge rule shall not be less than 70% of the maximum demand charge in the past 12 months.
- Official[01] PEA Electricity Tariffs (May 2023 onward) PDF: List Schedule 3/4/5 minimum charge rules and 15-minute demand definition.
- Official[02] BOI Utility Costs Page: Make a public summary of demand and minimum charge rules.
3.3 The key figures of Schedule 2 / 3, the salesperson must be able to read and speak them
3.3 The key figures of Schedule 2 / 3, the salesperson must be able to read and speak them
The key figures in PEA's current English manual are suitable for inclusion in training directly. Taking the voltage below 22 kV as an example: the TOU energy fee of Schedule 2 isPeak 5.7982 THB/kWh、Off-Peak 2.6369 THB/kWh, the service fee is33.29 THB/month;The TOU demand fee for Schedule 3 is210 THB/kW, the energy cost isPeak 4.3297 THB/kWh、Off-Peak 2.6369 THB/kWh, the service fee is312.24 THB/month。
This comparison illustrates two things. First, the electricity bill structure for small commercial customers may be more complex than that for residential customers, but it is also more worthy of optimization. Second, Schedule 3 users cannot just look at power savings, but must also look at demand and minimum charging rules. If new employees can explain this set of numbers in a smooth manner, they will already be more professional than many of their peers in the market.
In addition, the PEA manual also states: If the meter is installed on the low-voltage side of the customer's transformer, additional2%of kW and kWh to compensate for transformer losses. Although this kind of detail may not be used in every project, it can help the team form a habit: small commercial bills are not simple, and the structure and exceptions must be understood first when calculating.
| Rate items | Schedule 2 low voltage TOU | Schedule 3 low voltage TOU | training meaning |
|---|---|---|---|
| Peak energy fee | 5.7982 THB/kWh | 4.3297 THB/kWh | High value for spontaneous use during the day |
| Off-Peak energy fee | 2.6369 THB/kWh | 2.6369 THB/kWh | Night time saving value is lower |
| demand charge | none | 210 THB/kW | Schedule 3 cannot ignore demand logic |
| service charge | 33.29 THB/month | 312.24 THB/month | reflect category differences |
| Transformer low voltage side compensation | Depends on the situation | Plus 2% kW/kWh | Billing details will affect calculations |
3.4 Proposal algorithm for small commercial projects: Instead of reporting the system size first, calculate the saving structure first
3.4 Proposal algorithm for small commercial projects: Instead of reporting the system size first, calculate the saving structure first
The most suitable small business proposal algorithm for new employees is not to decide on 30kW or 50kW at the beginning, but to break down the customer bills first. The first layer identifies the proportion of electricity charges and demand charges; the second layer identifies the overlap between business hours and peak periods; the third layer determines the matching between system power generation and the 15-minute peak; the fourth layer determines the system scale, TOU, and whether energy storage or load management is required.
In practice, it is recommended to make two versions first:Conservative planOnly calculate the savings brought about by stable self-use, and do not write down the demand reduction and delivery income too high;Advanced planDemand improvement and future energy storage value should be properly discussed only when load data support is available. This way the proposal will be more stable and more like a professional consultant rather than a salesman.
The core value of this algorithm is to avoid over-promise. Small commercial customers usually pay more attention to authenticity than household customers because they often have financial personnel, accountants or bosses who do their own accounting. Once you overestimate your ROI, subsequent trust will be difficult to repair.
2. Read the bill: Separate energy charges, demand charges, service charges, Ft, and VAT.
3. Business hours mapping: Confirm the coincidence between customer load and peak period.
4. Generation matching: Estimate the proportion of self-consumption of the system during business hours.
5. Savings calculation:Annual savings = electricity fee savings + verifiable demand fee improvement + delivery revenue (if any)。
6. Payback period:Static payback period = total investment ÷ annual savings, and gives two levels of conservative/neutral at the same time.
3.5 When do small commercial projects need to consider energy storage, rather than just adding more components?
3.5 When do small commercial projects need to consider energy storage, rather than just adding more components?
One of the most common mistakes that many teams make when working on small commercial projects is that they reflexively want to make the system bigger when they see the customer's high electricity bill. However, if customer peaks occur in the evening, at night, or during short-term shocks, simply adding more components may not necessarily lead to better financial results. What is more worthy of discussion at this time is energy storage, load management or phased construction.
Whether energy storage is valuable depends on three things: first, whether the demand peak occurs during a period that cannot be covered by photovoltaic output; second, whether customers have higher requirements for power supply continuity; third, whether the TOU and business hours structure make it economical to 'shift peaks and fill valleys'. If these three items are not true, adding only energy storage will only make the project more expensive.
Therefore, in small commercial scenarios, energy storage should be regarded as a ‘tool to match specific load problems’ rather than a high-end option. Being able to explain clearly 'why batteries are not recommended now' is as important as being able to explain clearly 'why batteries should be made at this time'.
3.6 The correct way to combine corporate taxation and small business proposals
3.6 The correct way to combine corporate taxation and small business proposals
In small business scenarios, taxation is not the main logic, but it is often an important auxiliary logic that promotes decision-making. The correct approach is not to isolate tax incentives and exaggerate them, but to put them into a complete business proposal: the first layer is electricity bill savings; the second layer is cash flow stabilization; the third layer is potential tax optimization; and the fourth layer is brand and ESG narrative.
For customers who are eligible for tax incentives for enterprise-side energy-saving equipment, they should be clearly informed: This part must be confirmed by a tax consultant based on the equipment list, energy efficiency label, e-Tax Invoice, time of operation and the company's existing tax incentive status. In particular, overlapping tax incentives such as BOI/EEC must be excluded. Your value as a planner is to clearly explain the possibilities and conditions, not to make conclusions on behalf of the tax accountant.
A truly professional small business solution should let customers know which benefits are more certain and which benefits require further verification. As long as this line is maintained, the quality of the proposal will be significantly improved.
- Official[01] Thailand Revenue Department RD official press release (ปชส.3/2569): Provides the logic and restrictions of 1.5 times deduction for enterprises/operating entities.
- Official[02] Thailand Revenue Department supporting illustration: Clarify the requirements of 40(5)-(8), companies/partnerships, non-overlapping BOI/EEC, etc.