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BER calculation for PV install

  • 01-06-2021 01:43PM
    #1
    [Deleted User]
    Posts: 45,738 ✭✭✭✭


    Quick question regarding BER energy reduction per m2 after a PV installation system.

    I've been told on here the calculation used for a 5kwp system for a 150m2 house would be as follows:



    5,000w x 1.47 / 150m2 = 49 energy reduction per m2. You then subtract this from your current BER rating, which I have.


    However, what I don't know what the multiplier 1.47 is ?


    I can't find the calculation used anywhere. Even the SEAI site doesn't have it.

    Thanks!


Comments

  • #2
    sydthebeat
    Subscribers, Paid Member Posts: 43,960 ✭✭✭✭sydthebeat


    never heard of that calculation before....

    and i cant see the use of it either, as thats not how you calculate the PV input into the BER system


  • #3
    [Deleted User]
    Posts: 45,738 ✭✭✭✭ [Deleted User]


    sydthebeat wrote: »
    never heard of that calculation before....

    and i cant see the use of it either, as thats not how you calculate the PV input into the BER system


    Do you know how to calculate it? Thanks


  • #4
    sydthebeat
    Subscribers, Paid Member Posts: 43,960 ✭✭✭✭sydthebeat


    see appendix m here

    https://www.seai.ie/home-energy/building-energy-rating-ber/support-for-ber-assessors/domestic-ber-resources/deap4-software/DEAP-Manual-Version-.pdf


  • #5
    Calahonda52
    Registered Users, Registered Users 2 Posts: 12,959 ✭✭✭✭Calahonda52


    Interesting
    Page 135
    The electricity produced by the PV module in kWh/year is
    0.80 × kWp × S × ZPV
    where S is the annual solar radiation from Table H2 Page 122
    and
    ZPV is the overshading factor from Table H3. Page 122

    So lets look at the units
    ZPV is dimensionless. take at 1 for no over shading

    S is Annual solar radiation, kWh/m2/year


    So what units is the 0.8 if we end up with kWh/year

    0.8 * kW * kWh/m2/year * 1.0

    “I can’t pay my staff or mortgage with instagram likes”.



  • #6
    randomname2005
    Registered Users, Registered Users 2 Posts: 2,135 ✭✭✭randomname2005


    Haven't looked at the pdfs but that 0.8 might be general efficiency of solar panel systems.



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