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Seasonal Time of Day Tariff (STOD)
A variable electricity supply tariff based on higher unit charges during peak periods and lower unit charges during off-peak periods.

Secondary fuels
Fuels obtained from primary sources for example, electricity generated from burning coal, gas or oil.

Seller's Market
A condition in the market in which there is a scarcity of goods available and hence sellers can obtain better conditions of sale or higher prices.

Service Industry Code (SIC)
The SIC is a standard classification code that identifies the types of business conducted at the site.

Settlement
The payment of imbalance prices which occurs within 28 days of trades.

Settlement Agency
The body charged with determining where the generated electricity went to.

Settlement Fees
The fees, determined by the Settlement Agency and paid monthly, to cover the cost of distributing electricity.

Settlement Price
The official closing price of the day for each futures contract, established by the exchange as a benchmark for settling margin accounts and determining invoice price for delivery on that day.

Shape
The 'shape' formed by linking the peaks on a graph which shows the power (kW) used (on the horizontal axis) against the time of usage (on the vertical axis). It illustrates the varying magnitude of the load at a supply point over a period, consumers using a uniform quantity of electricity throughout a 24 hour period will have a flat profile; the normal shape for offices will rise during the day (when demand is highest) and fall at night (when demand is lowest). Suppliers will base their pricing of the electricity supply to a larger site on the 'Shape' produced from the analysis of that sites half-hourly data.

Shape out Clause
A clause in an electricity supply contract intended to cover the supplier against a variation in consumption during a contract year. It allows the supplier to vary the unit price if there is a significant decrease in consumption

Shipper
A shipper buys gas from producers / importers, transports this through the gas network by National Grid, and sells the gas to its customers. The shipper may have a contract directly with the customer, or may act on behalf of a 3rd party.

Shipper Interface Document
A document produced under the auspices of the National Grid.

Shipper Reference
The unique reference defined by a Shipper to allow for all deliveries to be tracked.

Shippers Agents
Work for 'Shippers' to carry out network processes on their behalf.

Short
A position in the market when the net position in the futures market shows an excess of open sales over open purchases, a seller who has sold a futures contract to establish a market position, a market position which obliges the holder to deliver.

Single Electricity Market Operator (SEMO)
The Single Electricity Market Operator (SEMO) facilitates the continuous operation and administration of the Single Electricity Market. SEMO is a joint venture between EirGrid plc and SONI Limited.

Site
A geographic location at which gas is consumed by the customer. There may be several gas meters at a site, which measure the volume of gas consumed.

Sleeve
A sleeve occurs when a buyer or seller are matched for price, but do not have credit in place so a counterparty is brought into deal both in the middle.

Small Site Peak Daily Demand
Small site PD Demand = Sum of (reference consumption) for all small sites.

Smart Meter
Two way communication system that displays accurate real-time information on energy consumption to the customer and back to the energy supplier.

Smart Metering
The ability to remotely read non-half hourly (NHH) meters. Data is more reliable and more accurate bills are produced.

Solar energy
The radiant energy of the sun that can be converted into other forms of energy, such as heat or electricity.

Spark Spread
A form of analysis used to compare gas prices with electricity prices, by converting the gas price into a price per MWh and subtracting it from the electricity price in that period, taking into account power station efficiency. A negative spark spread indicates that it is more beneficial to sell gas than to produce and sell electricity.

Special Purpose Vehicle (SPV)
A company created to run a project.

Speculator
An individual who invests in commodity futures with the objective of achieving profits by successfully anticipating price movements.

Spill
Surplus electricity produced by a generator unable to sell it.

Spot Market
The market for current transactions.

Spread
The difference between two prices, either across a time or between commodities or instruments.

Stack
The theoretical total generation capacity from all power stations sorted from the cheapest to most expensive generators.

Standard Offtake Quantity (SOQ)
See 'Maximum Daily Quantity'.

Standing Charge
A monthly or quarterly charge added to an energy supply invoice by the supplier to cover administrative costs.

Steam Turbine
A device which converts high-pressure steam into mechanical energy that can then be used to produce electricity by forcing blades in a cylinder to rotate and turn a generator shaft.

Storage Operators
Linked to gas networks, they operate facilities at which gas can be stored during months of low demand.

Strike Price
The price that is locked in through an option.

Sub Station
These play an important part of the national grid. They contain transformers that increase or decrease the voltage of an electric current.

Sub-Metering
The term often used when a property owner installs a separate meter to monitor the consumption of a utility such as water, gas or electricity.

Sulphur Dioxide (SO2)
A gas produced by the combustion of sulphur-containing fuels such as oil and coal.

Summer
The summer period, normally April to October inclusive.

Supplier
A person or company, generator, broker, marketer, aggregator, or any other entity licensed to sell energy to consumers using the transmission and/or distribution network, with respect to the supply of gas, a Supplier may also be a licensed 'Shipper'.

Supplier Activity
Energy efficiency work undertaken by suppliers to meet their energy efficiency targets.

Supplier Nominated Interruptible (SNI)
A site where the supplier has the right to interrupt the supply for commercial reasons.

Supply Contract
A contract between a supplier and consumer for the supply of energy.

Supply Hourly Quantity (SHQ)
SHQ is the maximum hourly consumption for a supply point.

Supply Offtake Quantity (SOQ)
The maximum daily consumption for a supply point.

Supply Point (SP)
A group of one or more meters for which National Grid shall make Natural Gas available for offtake by the Shipper.

Supply Point Administration (SPA)
The process by which Shippers and National Grid agree ownership of supply points.

Sustainable Energy Authority of Ireland - SEAI
Is a government funded organisation responsible for promoting energy efficiency in through the commercial, industrial and residential communities of Ireland.

Swap
The transfer of risk from buyer or seller to a financial intermediary. The intermediary guarantees a price and pays the difference if the market is higher. If the price is lower the swap user pays the intermediary the difference. A fixed-for-floating hedge arrangement.

Swaption
An option on a swap, or the right to enter into a price swap at a particular point in the future and at a set price without the obligation to do so.

System Buy Price (SBP)
The price paid in the 'Balancing Mechanism' by a party which requires more energy to meet its contractual commitments, prices are often volatile and high.

System load factor
The average hourly quantity of electricity available during the year expressed as a percentage of the maximum demand at the end of the year.

System Operator for Northern Ireland (SONI)
System Operator for Northern Ireland (SONI) Ltd is owned by EirGrid plc. Based in Belfast, SONI ensures the safe, secure and economic operation of the high voltage electricity grid in Northern Ireland and in cooperation with EirGrid colleagues is also responsible for running the all-island wholesale market for electricity.

System Sell Price (SSP)
The price paid in the 'Balancing Mechanism' by a party which has produced more energy than it had customers to buy, prices are often volatile and often negative meaning that payment would need to be made to dispose of the unwanted energy produced.