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Post by tattoo on Jan 25, 2017 18:00:07 GMT -8
I've got 4 100w panels, 40A MPPT CC and 4 230ah 6v batteries to 12 v..... I know there are many variables but My question is after several cloudy days and your batteries run down to 11.9v and the sun comes out for several days how many days should it take to charge to full float if all power is cut off so nothing is drawing on the system???
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Post by tattoo on Jan 25, 2017 18:53:16 GMT -8
Oh yea I only get about 4hrs of direct sun this time of year.....
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Post by jsb2000 on Jan 26, 2017 4:46:42 GMT -8
I would estimate 3-5 days under those conditions and criteria.
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Post by rabird on Jan 26, 2017 4:48:05 GMT -8
each panel is about 6A. 6A * 4 panels = 24A 24A * 4hrs = 100 ah (tilted directly to the sun) 230ah battery @ 11.9v is 60% discharged? 230 *.6 = 140 amp-hrs need to be replaced. 2 days This calculator can be used to determine how many hrs of sun for a location/time of yr/tilt angle. www.solarelectricityhandbook.com/solar-irradiance.htmluse facing directly south, and then pick a tilt. a flat or horizontal panel locally yields 2.6 in Jan and 6.2 in June! |
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Post by jsb2000 on Jan 26, 2017 10:31:41 GMT -8
230ah battery @ 11.9v is 60% discharged? 230 *.6 = 140 amp-hrs need to be replaced. Wouldn't four 230aH 6V batteries be configured in a series parallel configuration, making it a 460Ah bank rather than a 230Ah one? Thereby roughly doubling your 2 day estimate to fall into the range that I mentioned? |
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Post by rabird on Jan 26, 2017 12:18:00 GMT -8
230ah battery @ 11.9v is 60% discharged? 230 *.6 = 140 amp-hrs need to be replaced. Wouldn't four 230aH 6V batteries be configured in a series parallel configuration, making it a 460Ah bank rather than a 230Ah one? Thereby roughly doubling your 2 day estimate to fall into the range that I mentioned? yes, I missed 4 6v and assumed 2. |
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Post by tattoo on Jan 26, 2017 18:20:33 GMT -8
I want to thank you both for all the help... It's been three days and I'm almost there.... When I looked before the sun went down today they were at 12.5 so I would think tomorrow or the next day for sure... I will let you know...
Thanks again...
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Post by tattoo on Jan 27, 2017 9:21:20 GMT -8
Ok I have a question.. I'm thinking about adding 2 more panels to my system... I'm assuming that will help it to charge faster or will it?? If I'm right how many panels can I add to the system I have now before I will have to get more batteries???
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Post by jsb2000 on Jan 27, 2017 17:21:02 GMT -8
Ok I have a question.. I'm thinking about adding 2 more panels to my system... I'm assuming that will help it to charge faster or will it?? If I'm right how many panels can I add to the system I have now before I will have to get more batteries??? Adding panels will definitely help it charge faster, but your current 40A charge controller will not be able to handle the additional current safely. Your current 4 panels would max out at 33 amps, which is within the controller's rating. Adding a fifth would raise the potential current to around 42 amps, and a sixth would raise it to 50A. As far as batteries go, my rule of thumb is one group 27M 12V marine battery (90AH-ish) per 100 Watt solar panel. 50% drain = around 45AH which would take a single panel supplying 8 amps around 6 hours to recharge. If you limit the depth of discharge to 70%, that charge time falls to 3 to 3-1/2 hours. As for "how many panels can I add to the system before you have to get more batteries," that's not really the way to look at it. You can add as many batteries as you want, but it will take longer to recharge them. And, given the right capacity charge controller, you could add as many panels as you want to decrease the amount of time to recharge the batteries...plus have surplus power to run your loads while you charge. |
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Post by tattoo on Jan 27, 2017 19:44:28 GMT -8
Adding panels will definitely help it charge faster, but your current 40A charge controller will not be able to handle the additional current safely. Your current 4 panels would max out at 33 amps, which is within the controller's rating. Adding a fifth would raise the potential current to around 42 amps, and a sixth would raise it to 50A. As far as batteries go, my rule of thumb is one group 27M 12V marine battery (90AH-ish) per 100 Watt solar panel. 50% drain = around 45AH which would take a single panel supplying 8 amps around 6 hours to recharge. If you limit the depth of discharge to 70%, that charge time falls to 3 to 3-1/2 hours. As for "how many panels can I add to the system before you have to get more batteries," that's not really the way to look at it. You can add as many batteries as you want, but it will take longer to recharge them. And, given the right capacity charge controller, you could add as many panels as you want to decrease the amount of time to recharge the batteries...plus have surplus power to run your loads while you charge. Thank you and I had no idea...... So in other words I didn't buy what I thought or lead to believe I was buying??? I thought I was buying a system that I could add to if needed but it's about maxed out like it is??? |
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Post by rabird on Jan 28, 2017 4:32:49 GMT -8
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Post by tattoo on Jan 28, 2017 5:54:31 GMT -8
Thanks for the info..^^^^ So this is a common problem?? Well not a problem but it's something they don't really come out and tell you when your looking for a system... This is a true learning curve for me and I'm sure many other people...
I figured you could add more panels to this 40a MPPT charger but I think I'm understanding now. OK on a 60a charger you can have as many as 6 maybe 7 panels? Or a 10a charger you can just use only 1 or 2 panels am I right???
I really like my system don't get me wrong but the more I learn the more I have to learn... But I guess that's why you have to ask many many questions...
Thanks for all of the help..
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Post by rabird on Jan 28, 2017 10:09:54 GMT -8
Its common to apply 125% (or 80% to the controller rating) to the max current of a panel (Isc).
In extreme cold and with certain light conditions the panel makes more power than is rated watts.
A 100 watt panel ought to have an Isc of say 6.3A (they differ)
6.3A * 1.25 = 7.875A 40A / 7.875A = 5 panels
They do make controllers that can be over powered, the concept is most of the time the panels will never make full power and when they do those controllers have the ability to limit power, so ya over load them on purpose for winter and cloudy days!
The options are limitless!
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Post by tattoo on Jan 29, 2017 13:58:03 GMT -8
Ok Now that I'm understanding this more I have a question??? I'm wanting more charging so now that I know I can only add one more panel that's no help. So if I want to add 4 more panels or a wind type charger. I will have to add another CC I know and I assume my 2000w inverter should be just fine. My question is do I just hook it up to my 4 batteries the same way they are hooked up now and bypass my current CC or will it have to be wired up differently to the batteries?? Or is my batteries maxed out?  Man this can be confusing..... |
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Post by rabird on Jan 29, 2017 17:23:21 GMT -8
I have one of these coming in a few days www.homedepot.com/p/Grape-Solar-40-Amp-PWM-Solar-Charge-Controller-with-Bluetooth-GS-PWM-40BT/207100856what I like about it is bluetooth via an app from them to be able to monitor the battery and change charge profile voltages. hook up additional cc just like you have, they both will charge at the same time, having them both set (if programable) to the same voltage set pts will be a plus. 460 ah, charge @ 10-20% of capacity, thats 46-90A charger! maxed out, NO, you are near a min of 5% charge rate. |
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Man this can be confusing.....