julmou Posted June 13, 2022 Share Posted June 13, 2022 Good morning, As I was designing a stand-alone system, I noticed a trend that I can't quite explain... regarding the dynamic ageing of the battery (wear-and-tear due to number of cycles). I understand that, the deeper the DOD (Depth-Of-Discharge), the more degradation, as is explained in this section of the Help : https://www.pvsyst.com/help/battery_ageing.htm However, I noticed in my simulations, that I was getting the opposite. The more I had a system with a high SOCmean (battery around 60-100% most of the time) the more I had dynamic wear (SOWCycl around 89%), and the opposite is true: in a system with deep DOD (SOC around 20-30-40% most of the time), my dynamic wear is much better (SOWCycl around 94%). I can't really explain it... Please find details about the said simulations below: Site: Dakar, Orientation: 35° tilt (optimized for winter), User's Needs: Load a CSV file, Household_BDEW template, re-scaled to 7000 kWh/year Battery set: Sonnenschein 12V 190Ah Pb Sealed Gel Solar S12/230A, PV module: SunPower 400W 55V SPR-MAX-400, Universal Controller Direct Coupling Case 01 -> Autonomy 3.4 days: 4x10=40 batteries, 1900Ah ; PV array oversized on purpose to illustrate the issue: 16 modules 6.4kWp Case 02 -> same system but with much smaller array of 8 modules, 3.2 kWp (and deeper DOD as a result) Case 03: without going to the extreme, a medium-sized 4kWp array, gives us SOWCycl 92.6% and SOCmean 43.3% 6.4 kWp -> SOWCycl 89.1%, SOCmean 82.3% 4.0 kWp -> SOWCycl 92.6%, SOCmean 43.3% 3.2 kWp -> SOWCycl 93.9%, SOCmean 33.9% As you can see, we have less wear on the battery when the DOD is deeper... I don't understand this. Would you mind helping me figure out what's going on? Thanks so much, Julien Link to comment Share on other sites More sharing options...
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