Hi Everyone :
First time here for me and new to PV technology. After going through various tutorials/forum posts, some things are not readily apparent to me. Thought I should post some of the issues confounding me here - maybe, I can pick up nuggets of knowledge here and there!
Assuming I have a system like this in mind:
Questions I can't figure out ( cross eyed starring at this spreadsheet for awhile now):
That's it! Many thanks!!
First time here for me and new to PV technology. After going through various tutorials/forum posts, some things are not readily apparent to me. Thought I should post some of the issues confounding me here - maybe, I can pick up nuggets of knowledge here and there!
Assuming I have a system like this in mind:
- total energy demand for one day = 21,177 wh/day
- nominal system voltage = 48v
- days of autonomy = 5 days
- average operating time per day = 4.1 hrs.
- Depth of battery discharge = 80%
- insolation for critical design month = 4.5 hrs/day
- max rated module current = 5.76
- max rated module voltage = 54.7
- max module power = 315
Questions I can't figure out ( cross eyed starring at this spreadsheet for awhile now):
- I came up with a required battery capacity of 3,064 ah. How long will the array take to charge this from the 20% level to 100% ?
- Does the array sizing take into account the need to charge the batteries whilst meeting load requirements? This is a system in a country where the grid supply is erratic during the day so the panels might be pulling double duty charging batteries used the previous night and also driving critical loads during the day. Looking at the calculation for array sizing, I only see an adjustment for battery charging efficiency. but not anything that accounts for meeting load requirements and charging batteries? Or maybe I am looking at this all wrong?
- Is it absolutely important to keep the number of batteries in parallel less than or equal to 3? For PV systems designed for relatively large load requirements - like 21,177 wh/day, I can't get this down to 3 without some ridiculous battery capacity selected.
- Using the figures above, i came up with a nominal array output of 8,190 w. What does this number mean? How does it jive with the daily energy demand of 21,177 wh/day and the battery capacity of 3,064 ah ? I guess I am looking to validate if this is enough? Do you guys have a way of checking to ensure the battery and array sizes are optimal and not over or under sized?
That's it! Many thanks!!
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