In an off grid solar system in a tropical/desert like climate which deep cycle battery is best, flooded or Gel and if Gel, Puregel VRLA or AGM and why?
Flooded, VRLA or AGM
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First eliminate gel as it it is too sensitive and fragile for cycled service. It cannot tolerate the high recharge rates required by solar. The gel dries out from rapid charging and the damage is permanent and accumulative. Second point there are two types of Lead Acid Battery. One being Flooded Lead Acid and the other is VRLA. In the VRLA family is two sub groups of AGM and Gel and we already eliminated Gel.
Now to answer your question. Flooded should always be the first choice for many reasons. They cost less and last longer period, and that is all you really need to know.
AGM is more of a niche application well suited for mobile applications like RV's, Trailers, and air planes where spills cannot be tolerated, and weight is an important factor. Also in extreme cold climates of -40 F and below because AGM will not freeze. Note fully charged FLA is good to -60 F. Another niche application is where one needs very high Charge and Discharge rates. Example in a place like Seattle WS where in winter they have less than 2 Sun Hours for much of the winter, and panel wattage's must be very high to recharge in a day which would give FLA battery problems. So before you consider AGM, consider is it worth the expense. AGM cost roughly twice as much as FLA for a given capacity, and last roughly half as long which means the long term cost of using AGM is 3 to 4 times more than FLA which is significant and a game changer once you are in the know.MSEE, PE -
First eliminate gel as it it is too sensitive and fragile for cycled service. It cannot tolerate the high recharge rates required by solar. The gel dries out from rapid charging and the damage is permanent and accumulative. Second point there are two types of Lead Acid Battery. One being Flooded Lead Acid and the other is VRLA. In the VRLA family is two sub groups of AGM and Gel and we already eliminated Gel.
Now to answer your question. Flooded should always be the first choice for many reasons. They cost less and last longer period, and that is all you really need to know.
AGM is more of a niche application well suited for mobile applications like RV's, Trailers, and air planes where spills cannot be tolerated, and weight is an important factor. Also in extreme cold climates of -40 F and below because AGM will not freeze. Note fully charged FLA is good to -60 F. Another niche application is where one needs very high Charge and Discharge rates. Example in a place like Seattle WS where in winter they have less than 2 Sun Hours for much of the winter, and panel wattage's must be very high to recharge in a day which would give FLA battery problems. So before you consider AGM, consider is it worth the expense. AGM cost roughly twice as much as FLA for a given capacity, and last roughly half as long which means the long term cost of using AGM is 3 to 4 times more than FLA which is significant and a game changer once you are in the know.
If one has 5 (12Vdc 240W 8A) panels in parallel into a 40A MPPT controller connected to bank of 4(12V 200AH) in parallel with good 8-10hrs of daylight how long/how many hrs to fully charge if AGM or FLA ?Comment
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If you have enough questions (and appear to be a slow learner) I am sure he will quote you a reasonable hourly rate.SunnyBoy 3000 US, 18 BP Solar 175B panels.Comment
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Now the bad news. We cannot wire your panels in series to take advantage of much less expensive wiring and wiring losses. This means you must wire them in parallel which is BAD NEWS. Son dpoint since you have grid tied panels which is a good thing you must use a MPPT controller. Based on 1200 watt input and 12 volt battery you wil have to use a 80 amp MPPT controller, or really two 60 amp controllers because maximum charge current from 1200 watts is 100 amps on a MPPT controller.
If you decide to cheap out and use a PWM controller, all you would need is a 40 amp controller. If you do that with your panels will change your 1200 watt panel into 12 volts x 40 amps = 480 watts. Just as well throw 3 panels away.MSEE, PEComment
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Dereck (Sunking) is not a battery engineer specifically, but is a PE who has spent most of his professional career designing off-grid power systems for commercial users.
If you have enough questions (and appear to be a slow learner) I am sure he will quote you a reasonable hourly rate.Comment
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No such thing as a Battery Engineer to my knowledge. I am an Electrical Engineer with 33 years or battery plant experience.
OK like I said you do not have 12 volt panels, they are 30 volt panels. Not to worry as they will work just fine on a 12, 24, or 48 volt battery system. Since you have a Prime number of panels, 5, you only have two configuration options open to you of either all in series, or all in parallel. Make note you have 5 x 240 watts = 1200 watts.
Now the bad news. We cannot wire your panels in series to take advantage of much less expensive wiring and wiring losses. This means you must wire them in parallel which is BAD NEWS. Son dpoint since you have grid tied panels which is a good thing you must use a MPPT controller. Based on 1200 watt input and 12 volt battery you wil have to use a 80 amp MPPT controller, or really two 60 amp controllers because maximum charge current from 1200 watts is 100 amps on a MPPT controller.
If you decide to cheap out and use a PWM controller, all you would need is a 40 amp controller. If you do that with your panels will change your 1200 watt panel into 12 volts x 40 amps = 480 watts. Just as well throw 3 panels away.Comment
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To put those panels in parallel means you need a combiner box with at least 4 circuit breakers (3-15 amp breakers and 1-50 amp breaker, and a large feeder cable going to the controller. If that distance is say 30 feet you would need #4 AWG copper conductor that cost around $1.25 per foot and you would need 60 to 70 feet of cable. You will have spent several hundred dollars in equipment trying to make it work.
Wire the panels in series and you do not need any breakers, combiner boxes, and only need to use 1 run of #16 AWG wire from the panels to the controller which will cost about $10 for the wire.
But please do it your way. Merchants want your money more than you need it.MSEE, PEComment
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