Steps

  1. Compute the foreseen battery capacity and adjust it using the MDOD and margin factor.
    Solution: Solution: 411.17 kWh
    [ Days \ of \ autonomy \ * \ Total \ daily \ load \ *\ Margin \ factor \ / \ MDOD ]
    [The total daily load has to be taken from an average between full and medium occupancy scenario]
  2. Adjust the datasheet values coming from the PV panel considering the expected average temperature during the year.
    Solution:V_{mpp} = 30.59 V ;I_{mpp}=13.44 A ;P_{mpp}=411.06 W)
    [V_{mp} = V_{mppSTC}+(K_{V}*(T_{avg}-25°C))
    I_{mp} = I_{mppSTC}+(K_{I}*(T_{avg}-25°C))
    P_{mppSTC}=V_{mppSTC}*I_{mppSTC},
    with Kv and K_{I} the V_{OC} and I_{SC} temperature coefficients, respectively.
  3. Adjust the maximum required production using the expected array to load value.
    Solution: 54.82 kWh
    [Total \ daily \ load\ * \ array \ to \ load \ value]
  4. Given the controller and PV panel data, calculate the foreseen daily energy production.
    Solution:Solution: 1.37 kWh
    [pvout*P_{max}^{module}*\eta_{inverter}*(1-systemlosses)]
  5. Compute the minimum number of required PV modules.
    Solution: 40
    [ roundup(Adjusted \ total \ daily \ load/ forseendailyPVenergy ) ]
  6. Determine the number of modules in series and of strings in parallel. Then, calculate the actual number of required PV modules.
    Solution: 40
    [modules \ in \ series \ = \ \frac{System \ nominal \ voltage}{ (module \ nominal \ voltage)} \ = \ 19.6 ~ 20 ]
    [ strings \ in \ parallel\ = \ \frac{minimum \ number \ of \ modules}{modules \ in \ series}=2.04 ~ 2]
    [ Actual \ PV \ modules \ = \ (modules \ in \ series) \ * \ (strings \ in \ parallel) = 40]
  7. Now choose the most suitable power converter among those reported in the proposed datasheet, without unnecessary oversizing.
    Solution: Model 15k
    [Model 15k has a rated DC input voltage of 600 V that matches with the voltage of the PV system, and it works at 230 V in AC side with a maximum of 15 kW. It also has 2 MPPT trackers that are perfect for the foreseen 2 strings of the plant. Furthermore, it has an integrated battery management system with a discharge peak of 16.5 kW that corresponds to 27.5 A of discharge current at an assumed 600 V battery voltage and a running current of 26.25 A per string. Therefore, all the requirements are met. Now the last step is to select the most suitable battery model in the market compatible with the chosen converter.]