Full PHI 3.8 Solar Battery specification
The number you see in the battery name is the maximum rated capacity under perfect conditions with 100% depth of discharge. To calculate the real battery capacity, you need to work with some basic battery characteristics, which can be found in the spec sheet.
Capacity shows how much energy a single battery can store. Usually, battery capacity is measured in Ah (ampere-hours), but, for your convenience, some manufacturers indicate capacity in Wh (watt-hours). It helps you compare your energy needs and the battery capacity to make the right choice. If the capacity is indicated in Ah, here is how to convert it to Wh:
battery size (Ah) * battery nominal voltage (V) = battery capacity (Wh)
Power rating shows how much electricity can be drawn from the battery to power your electrical devices, measured in kW. A battery with a high capacity and low power rating supplies a low amount of electricity for a long time. That energy would be enough to supply only a few devices. However, a low power rating is a good choice for backup generators. On the other hand, a battery with low capacity and a high power rating could run your entire home, but not for long.
Depth of discharge (DoD) shows to what extent a battery can be discharged without being harmed. For example, let's assume you have a solar battery with a 10 kWh capacity and a recommended DoD of 80%. This means you shouldn't use more than 8 kWh before you recharge your battery again.
Round-trip efficiency shows how much energy the battery loses while just storing it. The higher the round-trip efficiency is, the less energy you lose.