Battery bank : lead acid

[cisumma]

Matt@ surplussolar.com
400 watt panels $.48$ / watt
Monocrystline.

I have a flat roof and an ideal SSW facing exterior roof ideal for 100 watt panels. These monsters would have to lay on the flat roof I imagine. I just didn't want to compromise the roof yet. Are their any drawbacks from using 400 watt panels?

 

[wholybee]

Finally, what am I missing here if I am expecting to achieve 6,7 or 8 or the calculation ov 11.67 hours out of a mere 2 volts of available potential difference of my battery bank.

Pay close attention to the units (V, A, Ah, W, Wh) in my description below.

It isn't volts to worry about, it is Wh. (Watt Hours) Volts alone will not tell anything about how much available power is in the battery.
A watt is volts x amps. A watt hour is watts x hours. A 300 watt panel delivers 300W. If it delivers 300 watts for 2 hours, that is 600Wh. Note that the unit (Wh) follows the math used to derive it. (watts x hours) Batteries are usually rated in Amp hours. Since a watt is volts x amps, to convert Ah to Wh you need to multiply Ah by the volts. So, a 12V battery that is 80Ah is 960Wh. From that, you can estimate how long it will take a 300W panel to charge it, over 3 hours, if there is full sun and the panel is producing 300 watts.

Then you can work the other way for how long the battery will last. If your refrigerator uses 5 amps at 12 V, then you can divide 80Ah by 5A, and get 16 hours.

There are other considerations concerning efficiency and how much capacity in a battery is really usable, but that should cover the math and help you understand the terminology at least.

 

[cisumma]

I am hoping to come up on like 1600 watts polycrystaln; however, i might have a delay on purchasing a controller and I understand that the output of the controller needs to accommodate my 1400AH 6 volt VMAX lead acid 2s4p plus 3@ marine deep cell 12 volts daisy chained in. What is a price range of a typical controller?
Pointedly, if the panels are installed and absorbing electrons without being absorbed into storage does this hert the panel? Where does the DC current go? Will it need some sort of load?

 

[cisumma]

Pay close attention to the units (V, A, Ah, W, Wh) in my description below.

It isn't volts to worry about, it is Wh. (Watt Hours) Volts alone will not tell anything about how much available power is in the battery.
A watt is volts x amps. A watt hour is watts x hours. A 300 watt panel delivers 300W. If it delivers 300 watts for 2 hours, that is 600Wh. Note that the unit (Wh) follows the math used to derive it. (watts x hours) Batteries are usually rated in Amp hours. Since a watt is volts x amps, to convert Ah to Wh you need to multiply Ah by the volts. So, a 12V battery that is 80Ah is 960Wh. From that, you can estimate how long it will take a 300W panel to charge it, over 3 hours, if there is full sun and the panel is producing 300 watts.

Then you can work the other way for how long the battery will last. If your refrigerator uses 5 amps at 12 V, then you can divide 80Ah by 5A, and get 16 hours.

There are other considerations concerning efficiency and how much capacity in a battery is really usable, but that should cover the math and help you understand the terminology at least.

So, my 12v 1400ah and my 300 watts panel array : 4.6 estimated time to recharge?
And with harbor freight that is a wet dream ?

 

[Hedges]

So, my 12v 1400ah and my 300 watts panel array : 4.6 estimated time to recharge?
And with harbor freight that is a wet dream ?

You need to divide battery watt-hour capacity by PV array wattage. (not amp hour capacity divide by array wattage.)

12V x 1400 Ah = 16,800 Wh
16,800 Wh / 300W = 56 hours to recharge.
But that 16,800 Wh of lead-acid battery weights about 800 lbs.

Do you have 1400 Wh of battery?
1400 Wh / 12V = 117 Ah.
That could be one or two batteries.
1400 Wh / 300 W = 4.67 hours.

"I have a 1,400 ah vmax 6 v parallel/ series 12 v bank that I understand this translates to a roughly 700 ah."
If you have 1400 Ah of 6V batteries, and wire then in a 12V bank, then you have 700 Ah at 12V.
700 Ah x 12V = 8400 Wh
8400 Wh / 300 W = 28 hours to recharge.

What type of battery? If FLA, it may want 0.12C charge rate to properly mix the electrolyte.
8400 Wh x 0.12 = 1008W desired PV array

If AGM, it should be OK even with slow charge rate.

If this is a lead-acid battery, it always needs to get fully recharged. So determine daily power consumption of your freezer, especially in the winter. Look up "insolation" (effective sun hours) for your location in winter, and make sure PV array is sufficiently sized to power the freezer, make up for inefficiency of charge controller, batteries, inverter (if applicable) with power to spare.

 

[cisumma]

Absorbing all light isn't the problem. There are materials that absorb wide range of wavelengths. That produces heat. Solar-thermal panels are pretty efficient.

With PV, electrons need to be knocked out of their shell and across a diode junction. Any photon with less energy than is required to knock out the electron (e.g. IR) passes right through silicon. Silicon is transparent to IR, and I have an IR microscope that can look through silicon chip from the back side, see the circuit on the front.

Photons with more energy knock out the electron and produce PV current. Any excessive energy beyond what was needed to knock out the electron gets wasted as heat. So a silicon photo cells is most efficient close to a single wavelength. Today, you can buy PV panels of single-crystal or poly-crystaline cells that convert about 20% of the 1000 W/m^ sunshine to electricity.

There are more efficient panels. By layering thin films of different materials, they first capture higher energy photons, and let lower energy photons pass through to the next layer. Thin layers don't capture all the photons of right energy due to probability of interaction. A few micron thick layer misses some photons. A 10 mil thick wafer catches most. And, price of thin-film processing makes these panels more expensive per watt.

Today, silicon single-crystal and poly-crystaline panels are in the sweet spot of price-performance. Lower cost technologies take up more area, which costs materials and labor. Higher efficiency technologies cost more per watt, are useful for applications that have to be launched by rocket.

Best deal today is slightly used high quality panels. You can pay $0.12 to $0.50/watt from vendors like SanTan Solar. Cost of PV panels may be just 25% of what you spend on a grid-tie system, less of a battery-backup system.

Quality of panels is key, because some brands/models have failed. Here's a link; you can register and download free reports for a number of years. Try to buy brands rated has high performing in accelerated stress tests.

Is there a reliable resource to compare panel makes/models

SanTan treats you right. I did a quick visual inspection as I unloaded each panel. Where I saw damage, he took care of that. I had bought extra, so had spares, and nothing had to be shipped to resolve the problem. He turns over a huge quantity. If you assembled an array and they all/most fell...

diysolarforum.com

Nice microscope by the way. You could probably incorporate some Biomimicry of the iris of the moth's eye and look at its effects on the loose elections and redirect and eliminate the latent heat problem.
That's an awesome set of tools ,dude.
Take care.
Ripping eyeballs out moths ; lol, not sure about that one.

 

[cisumma]

You need to divide battery watt-hour capacity by PV array wattage. (not amp hour capacity divide by array wattage.)

12V x 1400 Ah = 16,800 Wh
16,800 Wh / 300W = 56 hours to recharge.
But that 16,800 Wh of lead-acid battery weights about 800 lbs.

Do you have 1400 Wh of battery?
1400 Wh / 12V = 117 Ah.
That could be one or two batteries.
1400 Wh / 300 W = 4.67 hours.

"I have a 1,400 ah vmax 6 v parallel/ series 12 v bank that I understand this translates to a roughly 700 ah."
If you have 1400 Ah of 6V batteries, and wire then in a 12V bank, then you have 700 Ah at 12V.
700 Ah x 12V = 8400 Wh
8400 Wh / 300 W = 28 hours to recharge.

What type of battery? If FLA, it may want 0.12C charge rate to properly mix the electrolyte.
8400 Wh x 0.12 = 1008W desired PV array

If AGM, it should be OK even with slow charge rate.

If this is a lead-acid battery, it always needs to get fully recharged. So determine daily power consumption of your freezer, especially in the winter. Look up "insolation" (effective sun hours) for your location in winter, and make sure PV array is sufficiently sized to power the freezer, make up for inefficiency of charge controller, batteries, inverter (if applicable) with power to spare.

Its every bit of 800 lbs
Vmax 6 volt 225 ah : 2s4p plus 3@ 12v marine deep cycle ( 135+- AH) each.

 

[cisumma]

56 hrs sounds more like it because fully charged and brand new last week and every day after sundown I begin the evening ( 0.1 ) volt less then the night before. Lol , I am grid charging now until I get my 16,000 watts ; then, the math should look better. ( hint, hint do you know where to get a pallet of 12 v 100 watt panels?)
Anyway, I devided wrong so I will have to review that.
Thanks

 

[cisumma]

You need to divide battery watt-hour capacity by PV array wattage. (not amp hour capacity divide by array wattage.)

12V x 1400 Ah = 16,800 Wh
16,800 Wh / 300W = 56 hours to recharge.
But that 16,800 Wh of lead-acid battery weights about 800 lbs.

Do you have 1400 Wh of battery?
1400 Wh / 12V = 117 Ah.
That could be one or two batteries.
1400 Wh / 300 W = 4.67 hours.

"I have a 1,400 ah vmax 6 v parallel/ series 12 v bank that I understand this translates to a roughly 700 ah."
If you have 1400 Ah of 6V batteries, and wire then in a 12V bank, then you have 700 Ah at 12V.
700 Ah x 12V = 8400 Wh
8400 Wh / 300 W = 28 hours to recharge.

What type of battery? If FLA, it may want 0.12C charge rate to properly mix the electrolyte.
8400 Wh x 0.12 = 1008W desired PV array

If AGM, it should be OK even with slow charge rate.

If this is a lead-acid battery, it always needs to get fully recharged. So determine daily power consumption of your freezer, especially in the winter. Look up "insolation" (effective sun hours) for your location in winter, and make sure PV array is sufficiently sized to power the freezer, make up for inefficiency of charge controller, batteries, inverter (if applicable) with power to spare.

Cool math:

 

[cisumma]

Cool math:

16,800wh
And 1400ah/ 2 usable

 

[Hedges]

I know where to get a pallet of 4, 300W panels or 3, 400W panels. They probably weight less than 12, 100W panels. Take up less room, too.

My 120W (Astropower) panels weigh 26 lbs.
My 327W (Sunpower) panels weigh 41 lbs.

Vmax - is that AGM?
Probably best not to parallel "marine not really deep cycle" with it, they would have somewhat different voltages.

 

[Hedges]

16,800wh
And 1400ah/ 2 usable

Well, 1400 Ah/2 = 700 Ah raw at 12v, because you put 6V batteries in series to make 12V.

Not sure how much of that is "usable", don't see DoD vs. cycle life specs. I target 70% DoD for my AGM.

V6-225 6Volts 225AH Deep Cycle, High performance AGM Batte

www.vmaxtanks.com

"Warning: Do not use a charger with smaller amperage than the recommended Charging Current shown above.
Maintainers should ONLY be used to maintain a fully charged battery but NEVER as a charger."

Charging current 15A-55A per 225 Ah. So you're supposed to provide 60 to 220 A at about 14V to 15V for your 700 Ah, nominally 12V bank.
About 1000W of PV sounds like minimum.

 

[cisumma]

I know where to get a pallet of 4, 300W panels or 3, 400W panels. They probably weight less than 12, 100W panels. Take up less room, too.

My 120W (Astropower) panels weigh 26 lbs.
My 327W (Sunpower) panels weigh 41 lbs.

Vmax - is that AGM?
Probably best not to parallel "marine not really deep cycle" with it, they would have somewhat different voltages.

Righton , I know the12v are nice batteries I figured whg not just use them. Maybe the can be placed in another side system if they survive.
I have to decide on the PV purchase I could see where I could get burnt if u don't research properly. Thanks though I have to deckde.

 

[cisumma]

Well, 1400 Ah/2 = 700 Ah raw at 12v, because you put 6V batteries in series to make 12V.

Not sure how much of that is "usable", don't see DoD vs. cycle life specs. I target 70% DoD for my AGM.

V6-225 6Volts 225AH Deep Cycle, High performance AGM Batte

www.vmaxtanks.com

"Warning: Do not use a charger with smaller amperage than the recommended Charging Current shown above.
Maintainers should ONLY be used to maintain a fully charged battery but NEVER as a charger."

Charging current 15A-55A per 225 Ah. So you're supposed to provide 60 to 220 A at about 14V to 15V for your 700 Ah, nominally 12V bank.
About 1000W of PV sounds like minimum.

I am using a charger. That is bad?
Shoemaker 8 amp charger I have 2 of these but I am using only one now.

 

[cisumma]

 

[cisumma]

Ever seen in of these? I bought it way before the battery bank was enhanced.
Still dont know if I can us it. It just looked cool.
I just took it out of the box . I'd have to go over the specs. Not sure if I can use it for anything

 

[cisumma]

View attachment 44223

Judging from the tiny little input out put connections it seems to step down 12v to 75v to mV . What the hell do I do with this? Lol

 

[cisumma]

View attachment 44223

 

[Hedges]

I am using a charger. That is bad?
Shoemaker 8 amp charger I have 2 of these but I am using only one now.

Probably OK at least temporarily if it follows the proper voltage profile: Constant current up to a particular voltage, constant absorption voltage for a few hours, then drop to float voltage.

But the battery spec sheet called for minimum 15A charge per 225Ah battery (or series string of 2 6V batteries making 12V)
So with 2s4p batteries, it calls for at least 60A charge current.

You ought to put in enough PV for the recommended charge, 1000W of panels or more, and an SCC of at least 60A.

Note that you have enough batteries to wire for 24V or 48V system, reducing minimum charge current to 30A or 15A, which can be done with a less expensive SCC.

"Right now I am totally DC. I have a little Coleman DC cooler and it seems to run well using 4 to 7 volts. I do not know how to use a tester to measure amps.
I have the emergency DC lights available.
I guess my ambition to run a 12 anp deep freezer that runs on and off ( compressor doesn't seem to a lot)
So, is it possible that when I move to AC will be able to get a general idea of weather or not this configuration will run fluently?"

"DC Cooler" - is that a solid-state thermoelectric "Peltier" cooler? Don't run that off batteries - draws far too much power, very inefficient.

Make a 24V or 48V system, and buy an inverter to run off that. Use a DC-DC or AC-DC charger to keep 12V Marine/Deep Cycle batteries charged for 12V loads. Batteries are the most expensive part of a system, and you already have AGM batteries. Just buy a 48V inverter, inverter-charger, or hybrid. You could spend anywhere from a few $hundred to a few $thousand depending on the brand, quality, capability you want.

 

[cisumma]

For the life of me I cant seem to meter measure how many amps the coolers draw. I will probably consider using the the ac to DC plugs that come with it ( but those plugs seem to fail very quickly) once I evolve into an inverter because they do keep beer cold.
Naturally, basic refrigeration is necessity and I really don't want to start relying on propane and gasoline.
And I am not in a position to buy expensive appliances yet.
I'm hoping to keep a DC system and see if an inverter will maintain frozen food that can be held for preparation in a DC cooler of sorts.
But first, I am waiting for the clouds to part and for God to deliver $1500 of panels.
When I get a chance I will have to run through the math and try to evaluate if the deep freeze can be run on a timer to control at least 6 hours of operation. I am thinking that it might be possible to keep food frozen.
Not sure how the deep freeze will perform on a hot pull down for an initial freeze though.

 

[Tariq0101]

Isn't 1400$ a little too much for two 300w panels?
I bought two new Chinese mono 200 watts panels for about 150$ total.

Edit:
And after trying them for a week I'm pretty sure they are giving more than their rated amps, but the tilt is perfect for this season and the weather has been perfect lately.

 

[cisumma]

Isn't 1400$ a little too much for two 300w panels?
I bought two new Chinese mono 200 watts panels for about 150$ total.

Edit:
And after trying them for a week I'm pretty sure they are giving more than their rated amps, but the tilt is perfect for this season and the weather has been perfect lately.

Personally, I am in the market for panels and I believe the going perfured rat is $ a watt.

 

[cisumma]

Don't spend $1500 to add 600W, and don't spend $600 to add 600W.
Your $600 could buy 2400W of panels. Or fewer panels, and some supporting electronics.

Solar Panels | SanTan Solar

store.santansolar.com

There is a cost to ship a pallet by freight, but you can save some picking it up at he freight terminal (assuming you can carry the large pallets.)
Say shipping is $200. You can pay $400 for 800 to 1600W (or more if you buy the cheapest) and come out ahead.
Or, check eBay & Craigslist for a local vendor of used/surplus panels so no shipping cost.

Clearly, I need 2400 watts of PV I'd love to buy that for $600 . Is that possible?

 

[Hedges]

Clearly, I need 2400 watts of PV I'd love to buy that for $600 . Is that possible?

Follow the SanTan Solar link I gave. After selecting a model and quantity you want, contact vendor and ask for a price for that quantity, may get further discount.

Battery bank : lead acid

Hello; i was planning on adding 2@ 300 watt solor panels ($1400 +-). Is there a recommended brand that is good? Also, will 900 watts be able to charge a 1400 ah battery bank?

diysolarforum.com

If for grid-tie or mounting on your roof, get panels that still have UL stickers (cheapest $0.20/watt panels have those removed.)
Here's one for a little over $0.25/watt, would cost $670 for 2400W:

SunTech 285W | SanTan Solar

store.santansolar.com

Another, $880 for 2400W

Hansol 355W - SanTan Solar Store

Check out our brand new Hansol 355W 72 cell monocrystalline panels! They come with the manufacturers warranty! Only $0.41/watt!

store.santansolar.com

$576 for 2400W

Used 250W 60 Cell Poly Solar Panel Major Manufacturer - SanTan Solar Store

Used 250W and 255W solar panels. These are used panels, in good physical condition. Minor scratches and scuffs, typical for a used panel.

store.santansolar.com

In any case, plus about $200 more or less for shipping. I save the last mile (truck with liftgate) by picking up at freight terminal.

You will sometimes find similar deals locally, on Craigslist or sort eBay by distance. Some vendors have used panels removed from solar farms/commercial installs, and some have leftovers following an installation.

 

[cisumma]

Hansol 355W​