Day vs Night Load Profiles : Calculation Help

[juju]

I am getting myself confused with calculating the required array and battery size when faced with different day and night time load profiles. Maybe I am totally not getting how the math works, however it seems in a typical calculation, the total loads to be driven and the number of hours ( along with a host of other inputs - Depth of discharge, days of autonomy, insolation ...etc) are used. Especially with the hours of use for each load, I don't see a distinction being made between daytime and night requirements. I have a situation where the load profile at night is very different from the load profile during the day and I am not sure how to calculate the required array size to handle the daytime loads whilst at the same time charging the batteries for night time loads. I am thinking the batteries should be sized only to support the reduced night time load profile with a certain autonomy period built in.

Can anyone share a sample calculation of how this works, assuming you have a daytime load profile about 3 times as large as what the night time profile is? ( told you I was getting myself confused.). Someone clear the confusion for me! thxx

[Mike90250]

For about 4 or 5 hours in daylight, your loads are running directly off the PV panels and are not subject to the 100% overhead that battery powered loads need to use. However, your active daytime loads reduce the amount of power that is available to recharge the depleted batteries.

* 100% overhead:
20% loss from panels not producing nameplate power when warm
20% loss battery recharge losses
5% charge controller losses (MPPT)
15% loss inverter overhead/efficiency
(dang, I can't recall that last 20%)

[SunEagle]

For about 4 or 5 hours in daylight, your loads are running directly off the PV panels and are not subject to the 100% overhead that battery powered loads need to use. However, your active daytime loads reduce the amount of power that is available to recharge the depleted batteries.

* 100% overhead:
20% loss from panels not producing nameplate power when warm
20% loss battery recharge losses
5% charge controller losses (MPPT)
15% loss inverter overhead/efficiency
(dang, I can't recall that last 20%)

That's called memory loss.