why payback period incease with feed in trafic

[anees]

hello iam new with financing of pvsol 

my payback was 2.3 years with net merter 

 

 

BUT WITH SURPLUS FEED- IN payback is 4 years i can not understand why 

 

[developer_mh]

Hi anees,

thank you for your question. Let's say your PV system is producing 10000 kWh and your consumers need 5000 kWh per year. The main difference between net metering and surplus feed-in is the following:

• with net metering you are
  • feeding in the whole PV energy into the grid, so the full 10000 kWh
  • drawing from grid the whole energy needed by the electrical appliances, 5000 kWh
• with surplus feed-in the electrical appliances are covered first (if possible), and only the rest is fed into the grid. So
  • you feed into the grid the PV energy minus the direct use, let's say 8000 kWh if we assume that 2000 kWh can be covered directly
  • you draw from the grid the energy of the consumers that was not already covered by PV energy (5000 - 2000 = 3000 kWh)

It really depends on the financial system of the country or region you are planning the PV system for. But you can't really compare net metering and surplus feed-in like you did in your example, those are two different things.

Hope that helps a litte, kind regards,

Martin