Magnum Energy Integration Guide

505 Keystone Rd, Southampton, PA 18966
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[phone]
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[e-mail]
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Fortresspower.com
4. Calculate the required battery bank capacity based on actual loads.
Every load on the Back-Up Panel will need to be analyzed (load power and duration). All
total energy is calculated by summing the individual energies for each load. Assume the
following loads and a customer who wants to run 24 hours off batteries only:
1 Appliance Running wattage Operating hours/day Daily Consumption
2 Refrigerator 250 W 12 hrs/day 3 kWh
3 Lights: 100 W 6 hrs/day 0.6 kWh
4 Well Pump 3000 W 1 hr/day 3.0 kWh
5 Internet and continuous
Phantom Loads
100 W 24 hrs/day 2.4 kWh
6
TV 200 W 4 hrs/day 0.8 kWh
Sum 9.8 kWh
REMINDER! Always try to maintain the recommended Depth of Discharge
(%DOD) of 80%, for healthy battery life and performance.
1. 2 LFP-5’s = 10.24kwh. Compared to the required hypothetical sum, this
roughly yields a 97% DOD. Therefore, not acceptable.
2. 1 LFP-10 = 10.2kwh. Offering 2 LFP-10’s at 20.4 kwh yields approx. 48% DOD.
Acceptable, but oversized.
3. 1 eVault at 18.5kwh however, would be the better option.
∑ (
9.8𝑘𝑊ℎ
)
  
(

)
∑ (
18.5𝑘𝑊ℎ
)
   
(

)
𝑥 100% = 53% ≤ 80%
If the customer cannot supply the load information, or assumptions cannot be
made, the rule of thumb as an absolute minimum battery size is to match the power
rating of the inverter in kW to the energy rating of the battery in kWh. A single
Schneider inverter is rated at 6.8 kW meaning a minimum battery size of 6.8 kWh
would be required. In that case an LFP-10, with an 80% discharge capacity of 8 kWh
would be enough to meet the minimum battery size by this very basic calculation
method.