Photo-voltaic power source connecting to a grid: can I feed the greed?
It is fairly common in the UK for houses to have PV panels on the roof and, in some cases, for householders to sell electricity back to their supplier

See http://www.bettergeneration.co.uk/green-energy-factsheets/feed-in-tariffs.html


  A Feed-in Law states that electricity suppliers are obliged to pay a fixed price for electricity generated from renewable sources, set above the market price for fossil fuels, with the idea being that this will stimulate a much wider take-up of microgeneration. The FIT is made up of:
  
  
  Generation Tariff - Utilities are obliged to purchase all renewable electricity produced by households or businesses, with the price per kWh depending on the technology and the size of the capacity;
  Export Tariff - Any generated electricity that is not used by the premises can be exported to the grid, with the tariff set at 3p/kWh;
  Avoided Costs - Not only will households be paid for all renewable energy generated, they will also save the costs that they previously would have paid in electricity bills.
  
  
  As is clear from the above, one of the great things about the FiT is the financial reward. You would be paid for all Renewable Energy produced, even if 100% of the electricity is used on your premises.




Summary of solar PV tariffs

Total installed    Generation tariff with            Lower tariff 
capacity (kW)      eligibility date or after         (if EPC requirement not met)
                   1 January 2014 and before         with eligibility date on or
                   1 April 2014                      after 1 January 2014
                                                 and before 1 April 2014

&lt;4kW (new build 
and retrofit)      14.90p/kWh                        6.61p/kWh

&gt;4-10kW            13.50p/kWh                        6.61p/kWh

&gt;10-50kW           12.57p/kWh                        6.61p/kWh

stand-alone        6.61p/kWh                         6.61p/kWh


From an energy-saving trust


  If you generate your own electricity (eg with solar panels or a wind turbine) your energy supplier might pay you money. This is called a ‘Feed-in Tariff’ (FIT).
  
  How the scheme works
  
  You’ll get a set amount for each unit (kilowatt hour or kWh) of electricity you generate. The rates vary depending on:
  
  
  the size of your system
  what technology you install
  when your technology was installed
  who put the technology in place - you need to use a certified installer
  
  
  Contact installer companies or an electricity supplier for more information. You can receive payments from your current energy supplier, or you can choose a different one from the list of registered suppliers.
  
  The export tariff - selling surplus energy
  As well as the generation tariff, you can also sell any extra units you don’t use back to your electricity supplier. This is called an ‘export tariff’.
  
  You’ll get 4.5p per unit of electricity:
  
  
  for solar panels where you applied for FIT on or after 1 August 2012
  for other technologies where you applied for FIT on or after 1 December 2012
  If you applied for FIT before these dates you’ll continue to get 3.2p for each unit of electricity.
  


From UK Government