RVLiFe
Solar Enthusiast
- Joined
- Jun 14, 2021
- Messages
- 234
I noticed an issue with the spreadsheet that I wanted to bring to attention.
First, Cell P33 is supposed to add all of the DC Watt hours together (SUM(P6:32)) but instead refers only to P8:32 witch misses the first two cells in that column. Minor change but it can have a big difference if your first two items that you are trying to do an audit on are DC loads.
Secondly, I have a question regarding the logic behind the "Required Total daily Solar output (Sunny)" calculation in the Solar Array Sizing section. Can anyone explain why the formula adds both the batteries "Daily Storage Requirement" and the" min Battery capacity W-Hrs" together? Isn't this like doubling the capacity needed to recharge the battery? Also, the formula then multiplies the answer by the Max discharge from full CHARGE. No real need to do this.
Example: If the spreadsheet says that my Daily Storage Requirement is 1897 Watt Hours Per Day and I set a 85% Max discharge from full CHARGE, the min Battery capacity W-Hrs shows as 2231.2 W-hrs. My solar panel array only needs to put 1897 Watts back into the battery to fill it. I suppose a theoretical 2231.2 Watts to be on the safe side. Why would the spreadsheet need to add both values together and base the Required Total daily Solar output (Sunny) off of this? Then why multiply by 85%(or whatever User Input was entered)?
I understand if someone tells me that it is doubling the capacity to factor in being under load but for a lot of people, they use their lights and other loads after the sun goes down. At least that is when I use my lights. If I wanted to be certain I have the capacity, that is when I would change the number of days of storage capacity in the spreadsheet, not the amount of PV Panels needed. I can run some lights off of the PV panels without the battery but I can't run my inverter and heavy loads off of them. That's why you need to make sure you have the battery capacity first and then compute the amount of PV panels needed to put the entire capacity back into the batteries in the number of days that you are looking for. Am I wrong?
First, Cell P33 is supposed to add all of the DC Watt hours together (SUM(P6:32)) but instead refers only to P8:32 witch misses the first two cells in that column. Minor change but it can have a big difference if your first two items that you are trying to do an audit on are DC loads.
Secondly, I have a question regarding the logic behind the "Required Total daily Solar output (Sunny)" calculation in the Solar Array Sizing section. Can anyone explain why the formula adds both the batteries "Daily Storage Requirement" and the" min Battery capacity W-Hrs" together? Isn't this like doubling the capacity needed to recharge the battery? Also, the formula then multiplies the answer by the Max discharge from full CHARGE. No real need to do this.
Example: If the spreadsheet says that my Daily Storage Requirement is 1897 Watt Hours Per Day and I set a 85% Max discharge from full CHARGE, the min Battery capacity W-Hrs shows as 2231.2 W-hrs. My solar panel array only needs to put 1897 Watts back into the battery to fill it. I suppose a theoretical 2231.2 Watts to be on the safe side. Why would the spreadsheet need to add both values together and base the Required Total daily Solar output (Sunny) off of this? Then why multiply by 85%(or whatever User Input was entered)?
I understand if someone tells me that it is doubling the capacity to factor in being under load but for a lot of people, they use their lights and other loads after the sun goes down. At least that is when I use my lights. If I wanted to be certain I have the capacity, that is when I would change the number of days of storage capacity in the spreadsheet, not the amount of PV Panels needed. I can run some lights off of the PV panels without the battery but I can't run my inverter and heavy loads off of them. That's why you need to make sure you have the battery capacity first and then compute the amount of PV panels needed to put the entire capacity back into the batteries in the number of days that you are looking for. Am I wrong?
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