If you have a new account but can't post, please email Niamh on [email protected] for help to verify your email address. Thanks :)
New AMA with a US police officer (he's back!). You can ask your questions here

What size PV system/number of panels do I need?

  • 26-07-2021 9:57pm
    Registered Users Posts: 55 ✭✭ Pieterblurb

    Hi All,

    I am gathering quotes for a PV system and one of the basic starting points is the size of the system or how many panels we should install. I don't get a good explanation of the sales people for their assumptions to calculate this.

    Based on last year's usage + recently purchased EV I would estimate our yearly usage to be 8,400 kWh/year. This would be average of 23 kWh/day. Based on 3,5 hours sunhours/day average a system of 6.6 kW would be required. Is this calculation and these assumptions correct?

    2 of the 3 system installers insist on 4.5 to 5 kW systems? Am I missing something?


  • Registered Users Posts: 55 ✭✭ Pieterblurb

    Thanks for the great explanation @graememk. I am not too concerned about the payback of the system, but would be concerned about overpaying for it so the guide price is useful. I am going through the solar quotes thread indeed 😊.