Large energy storage systems for report state of energy (SoE) which is obtained by the ratio of the expected energy / full charge energy whereas estimation of SoC is based on different methods like Coulomb Counting.
SOC is the state of charge (percentage value), which gives an indication of the battery state during charge and discharge process as compared to its full-charge state, and SOE is the state of energy which indicates to the energy state in the battery. I think they are the same..
For more , check the following paper:
Article Electrical Load Profile Management Based on Storage Energy S...
Regards,
Hasan
The Following Links will Help you on that
https://en.wikipedia.org/wiki/State_of_charge
http://jes.ecsdl.org/content/159/8/A1298.short
In short they are not the same. Typically State of Energy is a statement of the batteries current cndition (relative to temperature age balance etc.) and state of charge is merely a measure of the remaining energy in the system vs. 100% energy storage capabilty. The second is not a direct measure of the battery health although a decent algorithm takes the health of the battery into account (therefore it is not normally pure coulomb counting. Where as the traditional use of State of Energy is to give an current estimate of the batteries capability vs. a standard (normally some Beginning of Life estimate at certain conditions). So in short SOE is an estimate and normally not reliable enough to be a primary factor in the management of the battery and traditionally has to show a great deal of change before it effects the overall calculations of battery key parameters. The primary factors normally used for SOE are temperature and internal resistance.
State of Charge is percentage of remaining Ah in cell. State of Energy is percentage of remaining Wh in cell. If you take Wh = Ah*Vnom , then you have same percentages all the time. But more valid way to calculate SOE is taking the area of SOC-OCV Curves multiply with nominal capacity and divided by total area of SOC-OCV curve multiply with nominal capacity (Area(at SOC=what it is)*Qnom/Area(at SOC=100%)*Qnom). With that, change 5% SOC would not be same change 5% SOE.
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