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Post by Admin on Oct 1, 2018 13:19:03 GMT
I see that would be a 10% reduction in Pmax based on temp (-.47% X (47.2-25)), now if you apply the 80% sun am I correct that Pmax NOCT would be ~70% of STC Pmax? Others not only report NOCT as a temperature but Isc, Vmp, Voc, Pmp at NOCT conditions!! You are correct, it is about 70-75% depending on whether you use 80%-85% for the sun rule. This can be both a moderately conservative or conservative value depending on your location, and many more factors which you are aware of. -Renogy Team |
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Post by Admin on Oct 1, 2018 13:28:59 GMT
Hi Rob, We apologize for the confusion. We made an error in reading your system requirements. For starters, what is your general area location? We misread you were going to utilize 600W (6 x 100W) panels as opposed to 6 x 300W panels with minimal usage throughout the day. The battery is appropriately sized as well as the panel suggestion in your chart. With that said, 4 x 300W panels is not enough to support your load usage and its relationship to battery consumption. You will need at least an 1800W system so you actually need 6 x 300W panels to support your loads and battery bank. Your minimum battery bank (assuming 50% depth of discharge) is 500Ah. You choosing to use 645Ah is "oversized" in the sense that your panels are not sized to adequately charge it back up in a day from 50% if you drain your batteries of 645Ah to 50%. There are other factors to consider such as not having sun everyday, more than normal load usage, seasons, and other conditions that are out of your control by which can lead you to consuming more than 50% of your your oversized battery by which the panels can not charge it back up in a day. This is why other members, such as bupkis, suggested you actually need even more panels than 6 x 300W. With that said, it seems as though you might need room for expansion. If you wanted, you can start off with 6 x 300W panels and connect them in series parallel. At the moment we do not have a Renogy controller that can handle more than 1800W on a 24V system (at least for standard system sizing), and therefore would recommend the Midnite 150/200A Controller which is sold on our website as well. -Renogy Team Wow, that is a lot of information. My general location is just about dead in the middle of Texas. I was asking earlier about 8 X 300W panels connected series/parallel with the Commander 60A MPPT but if I'm understanding things correctly the Commander is only able to use 6 300W panels connected series/parallel at 24V (1800W max). How many 300W panels would you suggest considering the Midnite 150/200A Controller, 24V 645AH battery bank, and the needs from the original post? A lot of this equipment will be running 24/7. I was hoping to find a solution that would charge the batteries and still provide enough power to run the equipment during the day and use the batteries at night. You can safely connect up to 8 x 300W panels on the Midnite 150A at 24V. You would need a combiner box to connect the panels in a 2 (series) by 4 (parallel) fashion. -Renogy Team |
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Post by tattoo on Oct 1, 2018 13:34:06 GMT
You are correct, it is about 70-75% depending on whether you use 80%-85% for the sun rule. This can be both a moderately conservative or conservative value depending on your location, and many more factors which you are aware of. -Renogy Team There are many variations in Solar that people never think of..... I'm really hoping that the OP/Rob can run all he has on his list with his system as stated but I really doubt it..... I always say figure what your wanting to run in watts with Solar with a Kill a Watt meter.... Then double it....
Then your safe... If not you will figure out what you can and can't run with Solar real quick....
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rob
Solar Newcomer
Posts: 5
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Post by rob on Oct 1, 2018 18:26:13 GMT
Thank you, everyone, for the help thus far. I've learned quite a lot. I'm curious about the combiner box. Why would it be needed? Couldn't I just connect the 2 series strings in parallel with MC4 Parallel Branch Connectors?
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Post by playersz28 on Oct 3, 2018 12:27:55 GMT
Thank you, everyone, for the help thus far. I've learned quite a lot. I'm curious about the combiner box. Why would it be needed? Couldn't I just connect the 2 series strings in parallel with MC4 Parallel Branch Connectors? Combiner box is just a place to bring the wires together and, depending on the application, protect and seal the entry point. I have one with 4 panels on the RV roof but I could just have easily used MC4 connectors and Y's to tie the panels together then pushed them through a hole in the roof and sealed it. The box allows me to use a larger wire for the downfeed than the MC4 runs though. |
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Post by Admin on Oct 3, 2018 15:25:19 GMT
Thank you, everyone, for the help thus far. I've learned quite a lot. I'm curious about the combiner box. Why would it be needed? Couldn't I just connect the 2 series strings in parallel with MC4 Parallel Branch Connectors? Combiner boxes are preferred when connecting a lot more panels in parallel. The MC4 Branch connectors have a 30A limit and with the 300W panels, you're closer to that threshold. It's for safety purposes. -Renogy Team |
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Post by bupkis on Oct 3, 2018 16:16:22 GMT
Thank you, everyone, for the help thus far. I've learned quite a lot. I'm curious about the combiner box. Why would it be needed? Couldn't I just connect the 2 series strings in parallel with MC4 Parallel Branch Connectors? you're welcome and thank you for the PM Like I said there are many things to consider, plus the urge to use more once you are up and running! Getting the batteries FULL, regularly, based on the makers requirements is so important for battery longevity. willing to learn more I will point you to a pdf by Victron, it explains the diff between PWM and MPPT and how heat is a MPPT killer! www.victronenergy.com/upload/documents/White-paper-Which-solar-charge-controller-PWM-or-MPPT.pdfhere's info on panel tilt for various times of the year. www.solarpaneltilt.com/ |
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Post by tattoo on Oct 3, 2018 16:28:26 GMT
Thank you, everyone, for the help thus far. Anytime I'm glad to help... And thanks for your PM..... |
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rob
Solar Newcomer
Posts: 5
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Post by rob on Oct 5, 2018 3:51:37 GMT
Thank you, everyone, for the help thus far. I've learned quite a lot. I'm curious about the combiner box. Why would it be needed? Couldn't I just connect the 2 series strings in parallel with MC4 Parallel Branch Connectors? you're welcome and thank you for the PM Like I said there are many things to consider, plus the urge to use more once you are up and running! Getting the batteries FULL, regularly, based on the makers requirements is so important for battery longevity. willing to learn more I will point you to a pdf by Victron, it explains the diff between PWM and MPPT and how heat is a MPPT killer! www.victronenergy.com/upload/documents/White-paper-Which-solar-charge-controller-PWM-or-MPPT.pdfhere's info on panel tilt for various times of the year. www.solarpaneltilt.com/Thanks, the white paper explaining the difference between a PWM and MPPT charge controller was very helpful. I learned a lot reading through it. |
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