Parallel grid mode
This is where the Cogeneration unit runs in parallel with the grid.

Pass Through Charges
Charges that appear on bills to cover the costs of third parties involved in the energy supply chain to deliver power.

Pass-through Contract
A fully transparent electricity contract based on fixed energy rates and variable transmission and distribution charges.

Payment Terms
Generally the maximum number of days credit available to a consumer once a supply invoice has been posted by the supplier, suppliers will frequently offer discounts for shorter credit periods and payment by direct-debit.

The variable volume of electricity used or required over and above the baseload.

Peak demand
The highest level of demand recorded on the transmission system (national grid).

Generally refers to the maximum generation or supply of electricity between 0700 and 1900 hours Monday to Friday.

Penalty Clause
A clause in a contract which is generally intended to protect the interest of the 'seller' rather than 'buyer' (see 'shape out clause' and 'take or pay clause').

Percentage Day
This refers to the percentage ratio of electricity used in the daytime against that used in the night. This information is used by suppliers to quickly identify the type of profile.

Photovoltaic (PV)
Direct conversion of solar radiation into direct current electricity by the interaction of light with the electrons in a semiconductor device or cell.

Maintenance carried out to a gas pipeline resulting in temporarily reduced availability.

Plant load factor
A measure of how intensely each type of generation plant is used. Calculated as the average hourly electricity supplied during the year expressed as a percentage of the average capability at the beginning and the end of the year.

Plant margin
The amount by which the capacity of a generating plant exceeds the peak demand - expressed as a percentage of the net amount of weather corrected peak demand less the total imports from external utilities.

Plant Outages
Generation plant taken off-line.

The participants in the market, sellers, buyers, traders and intermediaries.

The Electricity Pool - the price for electricity in this market is determined by market forces and is not regulated.

Power Exchanges
Trading arenas in which energy can be bought or sold normally up to two days ahead of real time, often via the Internet.

Power Factor (PF)
This relates to how efficiently electricity is used on your site. Certain types of equipment cause poor power factor, which reduces the capacity of the network to supply power. It is inversely proportional to its Reactive Power - normally assessed between 0.0 and 1.0, the lower the number the higher the cost to the consumer. Network Operators can charge customers for this through power factor charges.

Power Line
Electrical wires that carry electricity from the point of generation to the point of use.

Power Station Gate (PSG)
Point at which power station output is metered.

An additional amount agreed between buyer and seller over and above an existing benchmark. Also, the price paid by an option holder to an option grantor.

Pre-payment meter (PPM)
A meter which allows customers to build up a credit for their electricity consumption, using coins, pre-paid tokens or special keys.

Pressurised water reactor (PWR)
A nuclear reactor cooled by ordinary water which is contained under high pressure to prevent it boiling.

Primary electricity
Electricity obtained from nuclear, hydro and non-thermal renewables, but not from fossil fuels.

Primary fuels
Generator fuels obtained directly from natural sources e.g., coal, oil and natural gas.

Priority Service Register (PSR)
Energy suppliers are required to manage and promote a register of customers with special needs such as the elderly, chronically sick and people with disabilities.

Producers explore for and produce gas from, for example, the North Sea, passing it to 'Delivery Facility Operators'.

Profile Class
An indication of the metering installed at an electricity supply point, see Meter Point Access Number.

Refers to the next delivery period, for example the Prompt Month in September would be October, the Prompt Quarter in Q1 would be Q2.

Public Service Obligation

Public Electricity Supplier (PES)
A company which previously held a public electricity supply licence, covering both the supply and distribution businesses.

A type of option that gives the right to sell a commodity at a given price in the future.

A large metal tower that carries very high voltage power lines.

Thermal degradation of waste in the absence of air to produce char, pyrolysis oil and syngas.