Metering and Billing Systems

Overview

Net metering is a service to an electric consumer under which electric energy generated by that electric consumer from an eligible on-site generating facility and delivered to the local distribution facilities may be used to offset electric energy provided by the electric utility to the electric consumer during the applicable billing period.

Billing

Organising electricity distribution requires to determine:

• how much electricity is available
• how it is shared and limited
• how are the individual costs (tariffs) to be set

Different Tariff systems are practicable at different conditions:

(see also at Costs and Tariff Setting - Examples)

• Flat tariffs unlimited/limited
• Item based tariffs (pay per bulb/TV/Radio)
• Pay per usage (requires metering)

Standard kWh Meter

Advantages

Digital meter

Standard kWh meter

• technique is "state of the art"
  
• billing is fair and transparent
• reading can be uncoupled from tariff collection
• allows amount and time related tariffs (demand steering)

Disadvantages

• high costs (metering device)
• especially at rural areas in dev. countries the investment cost for a meter unit are way out of range
  
• dis- and re-connection in case of late payment

Pre-paid System with Coins or Cards

Pre-paid system

Advantages

• fair and transparent
• no meter reading
• no overdue costs
• no costs for dis- and re-connection
• close to “ability to pay”-variations
• coins less expensive than cards

Disadvantages

• relatively high cost for metering device
• less forgery proof
• costs for re-collection of coins and selling system for coins/cards

Current Limiter / Fuses

fault current breaker	Current limiter / fuse; price may be < 5 USD
100px-Electrical Fuse	DIAZED fuses

Advantages

• simultaneously protecting against overcurrent (actual purpose)
• cheap if simple versions
  
• no meter reading required => indirect power flat rate according to max. amperage

Disadvantages

• accuracy of cicuit breakers as load limiter fluctuates (even items from one batch have different trigger levels)
  => neigbours with same connections may be able to use different wattage
  
• fault current breaker are rarely available in < 1 Ampere range (1 A / 220 V => 220 Watt)
  
• time of usage not considered; less fair
• melting fuses are available and cheap but very easy to bridge (also temporarily) => encourage misuse
  

Flat Rate / No Metering / No Limiting

Only in well organised small communities a flat rate without limiting or metering will work. Consumers have to agree that everybody connected carries the same share of payment. If usage of electricity differs widely between the connected parties usually the "one tariff for all" is considered unfair.

Often such settings work only until the limit of the mhp is reached and power has to be rationed.

Advantages

• very cheap (no metering or limiting device)
• in rural areas of Indonesia common and accepted as long lighting is the common/only usage
  
• can be combined with number of appliances or installed wattage (social control)

Disadvantages

• provokes waste of electricity, no incentive for saving
• no load control / demand steering possible (peaks)
• can be unfair

Further Information

• Metering and Billing Battery Charging Systems (BCS)
  
• Net Metering
  
• Net Metering Brazil (FRE)