# setting up my solar panel system to run my pump!

Solar Expert Posts: 32
THE BIG QUESTION IS HOW MANY 60WATTS PANELS WOULD I NEED TO RUN THIS PUMP 24/7?

so i have a 20 watt pump at 120V

60Hz if that helps with anything

using ohm's law: P = E x I

20watts/120V=.167 Amps

now my solar panel says:
powers: 12V 60 watt

60W / 12V = 5 Amps?

yet the rating says 3.5 Amps on the back because i know solar is inefficient in that aspect.

am i doing this correctly?

since the solar panel system uses a 12 Volts and not a 120 Volts

what do i do from there to figure this out?

i have a ever last deep cycle battery... it last a long while before it drains all the way...

i want the pumps to run off my battery at night.

and use sunlight in the day.
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• Banned Posts: 17,615 ✭✭
Re: setting up my solar panel system to run my pump!

Welcome to the forum.

You're trying to put together an electrical jigsaw puzzle and you're missing the fiddly bits at the edges.:D

The pump is 20 Watts. It's 120 VAC @ 60Hz. It isn't going to run off a battery; it needs an inverter to turn the battery's DC power into AC power. The inverter will consume more power. The pump will probably consume a bit more than its rating too.

So the first thing you do is figure out how much battery & inverter you need to run the pump. 20 Watts isn't difficult to come up with (I'm going to guess this is a small pond pump or such like), so you won't need a big inverter for just that. If the ratings are to be believed then something like this Exeltech would do: http://www.solar-electric.com/xp-125-12.html It uses about 5 Watts itself, so your load has just increased to 25 Watts.

Now here's the thing: you need to supply 25 Watts * 24 hours which is 600 Watt hours. On 12 Volts that works out to 50 Amp hours, and since you don't want to discharge a battery below 50% you'd need at least a 100 Amp hour battery.

To recharge that battery you've got about 4 hours of good sunlight to work with, depending on your location. Might be a little more. And the sun doesn't always shine nicely. The shortcut way to determining that can be: 600 Watt hours (daily use) divided by 4 hours of sun to replace it = 150 Watts per hour. The next trouble is that panels don't put out their rated power. Usually they put out an average around 77% or so (again it varies with your actual locale and how well aimed the panels are). Best case: 150 Watts / 0.77 = 194 Watts of panel to support that pump. You might get by with 180 Watts (three 60 Watt panels) if the location and weather is good.

You will also need a charge controller to keep the panels from over-charging the battery. One that would handle up to 15 Amps of current, like this: http://www.solar-electric.com/pros15solcha.html

You will also need fuses: one for each panel (as they will be connected in parallel), one for the controller output, and one for the inverter.

Any help?

BTW, Ohm's law is: I = V/R You're thinking of power equation: W = V * A
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

i have the inverter... it is a 400 watt inverter and the pump plugs into it.
• Banned Posts: 17,615 ✭✭
Re: setting up my solar panel system to run my pump!
ElideN wrote: »
i have the inverter... it is a 400 watt inverter and the pump plugs into it.

A 400 Watt inverter might use more than 5 Watts for itself. If it is an MSW inverter it will also cause the pump to use more power.
Do you have this all working except the solar recharging? If so, do you know the Amp hour rating of the battery? That is very important both for how long it will last running the equipment and how much panel is needed to recharge it.
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

hey do u have skype ts3 mumble vent aim yahoo or hotmail messenger? i'd like to ask u summore questions.

i use every single chat program out there...

and thank you, you answered alot of my questions.

i also checked the amp on the pump it is drawing up 15 watts only... which is awesome!

and i live in texas which is even better! so 180 should suffice but now i must check on the battery...
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

do u have instant messenger?
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

Battery Height: 225 mm - 8 7/8 in
Battery Length: 260 mm - 10 1/4 in
Battery Width: 173 mm - 6 13/16 in
Cold Cranking Amps (CCA): 550
Core Charge Applicable: Yes
DIN Designation: BCI or EN Only
EN Designation: DIN or BCI Only
Right Or Left Hand Positive: Left
Post Location: Top Post
Reserve Capacity (Min): 140
Voltage: 12

i cant find amp hours anywhere...
• Banned Posts: 17,615 ✭✭
Re: setting up my solar panel system to run my pump!
ElideN wrote: »
Battery Height: 225 mm - 8 7/8 in
Battery Length: 260 mm - 10 1/4 in
Battery Width: 173 mm - 6 13/16 in
Cold Cranking Amps (CCA): 550
Core Charge Applicable: Yes
DIN Designation: BCI or EN Only
EN Designation: DIN or BCI Only
Right Or Left Hand Positive: Left
Post Location: Top Post
Reserve Capacity (Min): 140
Voltage: 12

i cant find amp hours anywhere...

That's because that is an automotive type battery; not designed for deep-cycle use. As such they don't give it an Amp hour rating. It will work for awhile, but not as long as the same size deep cycle would. Generally figure on 10 Amps @ 13.8 Volts for recharging. It isn't going to "like" the charging profile offered by solar equipment either.

Can't do the message thing: I'm coming to you via satellite from a Linux netbook in the middle of nowhere courtesy of solar-recharged battery-based off-grid system.
Re: setting up my solar panel system to run my pump!

It reads like a car battery. Usually, not very good for deep cycle application. Normally, car batteries will not last very long if cycled more than 10 or 20%--the plates are not heavy enough.

You might want to read the following:

Deep Cycle Battery FAQ
www.batteryfaq.org

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

685 CA marine deep cycle battery

http://www.autozone.com/autozone/accessories/Duralast-685-CA-marine-deep-cycle-battery/_/N-25uw?counter=0&filterByKeyWord=deepcycle&fromString=search&itemIdentifier=298374_0_0_

they carry only 3 deep cycle batteries which were those...

and the link above was the one i purchased
• Banned Posts: 17,615 ✭✭
Re: setting up my solar panel system to run my pump!

Ah; size 24M Marine/RV "deep cycle". Not a true deep cycle and not an automotive battery either.
From experience, these are about 80-90 Amp hours @ the 20 hr rate standard used for solar applications. A bit undersized for your needs. You'd find something like this more suitable: http://www.solar-electric.com/repoba12vo11.html
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

marine battery

http://www.walmart.com/search/search-ng.do?search_query=marine+battery&ic=16_0&Find=Find&search_constraint=0
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!
Ah; size 24M Marine/RV "deep cycle". Not a true deep cycle and not an automotive battery either.
From experience, these are about 80-90 Amp hours @ the 20 hr rate standard used for solar applications. A bit undersized for your needs. You'd find something like this more suitable: http://www.solar-electric.com/repoba12vo11.html

also i checked the pump and it is running at 12.5watts with a killawatt meter

so will a

550ca battery or 90ah
60watt and a 120watt solar panel at 12 volts
(controller included)
(inverter included)

run my 12.5 watt pump? 24/7?
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

i have a 250gph pump rated at 120v 60hz 20watts
i have a 60 Watt and a 120 Watt poly crystaline solar panel (total 180 Watts of solar panel)
i also got a duralast deep cycle battery from autozone 550ca at 90 ah
sunforce 30a controller for future-proofing
400watt modified power inverter

when i used my kill-a-watt meter and tested my pump on the wall i got 12.5watts and .19 amps at 120 volts ac, it works perfectly even though it draws low watts which is great...
when i plugged it up to my solar system i got around 10 watts .19 amp at 12 volts dc, it still works fine...
so i'd give it a 10-20watts peak.

so i multiplied 20watt x 24 hours = 480 watts required
and i know that a 550ca is a about 90 amp hours.
To recharge that battery you've got about 4-6 hours of good sunlight to work since i am in texas... in winter! that is coming soon!, getting darker.
480 watts / 5 hours = 96 watts per hour.
and due to natural inefficiency i did 96w/.75= 128 watts of panel

will a 180 Watts panel work for this system 24/7?

and i have a 60 watt and a 120 watt will it work on this system?
am i doing this correctly?

and does the current play in anywhere?

it is 190mA
• Banned Posts: 17,615 ✭✭
Re: setting up my solar panel system to run my pump!

Your load will be whatever the pump uses plus whatever the inverter uses. Going with the 'full' 20 Watts may not account for this. If you have instructions that came with the inverter see if it has specifications. You're looking for the Amps or Watts it uses.

Otherwise, it is 20 Watts * 24 hours which equals 480 Watt hours.
Divide that by the nominal system Voltage and you get approximately the amount of Amp hours used:
480 / 12 = 40 Amp hours. At a maximum 50% DOD this would mean at least 80 Amp hours of battery. Your Marine/RV battery will be marginal for this, and really will not like that level of discharge. Expect to have to replace it sooner rather than later. All Marine/RV batteries are the same in this respect: it's the internal construction and not the brand that makes the difference. A larger one will last longer, but still not as long as a battery designed for this type of use.

Now let's say your 80 Amp hour minimum is correct (although it probably isn't). To recharge that you need to check on two things. First that you have the potential for enough charge current. This should be around 10% of the battery's Amp hour rating or 8 Amps minimum. That would require:
8 Amps * 12 Volts = 96 Watts, less typical 77% efficiency rating = 124 Watts of panel minimum.
The other thing is to be sure you have the potential of harvesting the equivalent Watt hours. This has to include the DC to AC conversion, and looks a bit like this:
480 Watt hours (AC) * 2 (for over-all 50% system efficiency) = 960. Divide by the hours of "equivalent good sun" which is probably 5 there. That comes to 192 Watts of panel.

Remember that assumes the sun is good (not bad weather) and the angle is right (not tilted off) and the other conditions are favourable (high temps lower panel output, as will pollution, fog, et cetera). It is better to have more panel than less. 180 Watts is very close, but it would rely on the pump actually drawing only 12 Watts, the inverter not drawing a large amount, the battery being in good shape (that will soon change) and mostly the atmospheric conditions favouring charging.

If you're connecting dissimilar panels remember that for parallel connects it is important to have the Vmp of the panels be very close. As in less than 10% and preferably less than 5%. Otherwise you will lose some of the potential power to the Voltage difference.
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

what store is the most easiest to get to to get true deep cycle batteries? because i can hardly find any... all big chain retailers here such as autozone, walmart are the most common stores but they only have those marines... and not true deep cycle.
Re: setting up my solar panel system to run my pump!

For Mega Marts, it seems to be regional... Places with lots of golf carts, for example, seem to offer those golf cart batteries. Places with farming, for example Costco has drums of hydraulic fluid.

Otherwise, find a local battery distributor. Shipping can be expensive--so double check before you hit an Internet site.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 9,511 ✭✭✭✭✭
Re: setting up my solar panel system to run my pump!

I'd suggest "learning" with a cheap set of "box store" batteries, not primo grade batteries.
Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,

• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

awesome i just found battery plus and they had tons of golf cart batteries woot! it was right up my house lol! freaking awesome!

have you guys heard of these brands before i buy em?

B
C
Club Car
E
E-CarE-Z-GO
F
Fairplay
G
GEM Global Electric Motorcars
K
Kangaroo
L
P
W
Western Golf Car
Y

alot of 6 volts...
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

well i found my supply store now

but which one should i get?
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

350 for a trojan batter?!?!? holy cow...
• Banned Posts: 17,615 ✭✭
Re: setting up my solar panel system to run my pump!

Yes, Trojans are a bit pricey. :roll: Crowns tend to be somewhat less so. Sometimes you can get "store brand" batteries from places like Costco or Sam's, but the availability seems to vary widely. Many here have had good luck with these bargains.

Speaking of which, that's quite a collection of off-brand brands you've found. Chances are each and every one is made by one of the major manufacturers, albeit to the private label's specifications. Here's a link to a spot that gives a little insight to this phenomenon: http://www.scoop0901.net/AWAKE/FAQ/Battery/batbrand.htm (It isn't listed by make/manufacturer so it's a bit difficult to sort through.)

You could look into these bargains: see what the price/warranty is. Battery technology is very similar across brands, so performance should be as well. You might find a winner amongst them.
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

XD GEM Global Electric

has

RAYOVAC on It... im sure that one is popular because they make batteries everywhere...
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

oh no.... the list i posted earlier were golf cart names... lol... here's the link...

http://www.batteriesplus.com/manufacturer/574-SLI/Golf-Cart-Batteries.aspx
• Banned Posts: 17,615 ✭✭
Re: setting up my solar panel system to run my pump!

It wouldn't surprise me if the cart companies did sell batteries with their own labels on them - for more money, of course. Still likely to be made by one of the big companies.
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

i am actually going through a list of their golf cart manufacturers to try to find the best deal...
Re: setting up my solar panel system to run my pump!

AGM=Absorbed Glass Matt lead acid battery.

Basically, use fiberglass mat between plates and fill like a wet (but not dripping) sponge.

If the case cracks, the electrolyte will not leak out. Unlike GEL batteries, if there is too much charging current, there will not be a pocket of gas formed at the plate (which prevents further electro-chemical reactions). And the battery can be frozen without cracking the case (usually--the AGM "mats" are only filled to 95% capacity with fluid, allowing room for expansion.

AGMs are "sealed" "recombinant" batteries. Any oxygen+hydrogen gas that is formed during charging is recombined at a catalyst (typically in the cap) back into water. Of course there are limits and an emergency pressure relief (over charging and as batteries age, the catalyst will eventually fail).

Very good batteries for solar PV systems... However, they are 2x the price of flooded cell lead acid batteries and tend to be a bit easier to damage (overcharge). Also, they may not last quite as long in service (a bit of disagreement over that statement here).

I ain't no battery expert.

Deep Cycle Battery FAQ
www.batteryfaq.org

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

bb

so which one would u prefer and or currently use?

flooded
gel
agm

?
Re: setting up my solar panel system to run my pump!

What is your expectations? Will you be monitoring the system closely or only hit and miss?

Basically:
• Flooded Cell: Cheap, pretty rugged, a bit messy, have to add water ~2 months. Great first battery bank. Best bang for the buck.
• AGM: About the "ideal" lead acid battery. More efficient, cleaner, no maintenance of electrolyte levels. 2+x as expensive as flooded cell. Highly recommend a Battery Monitor for real time monitoring of state of charge (cannot measure specific gravity with sealed/GEL batteries).
• GEL: Not recommended for solar applications. For solar, you should have 5-13% or so rate of charge for proper off-grid system operation (limited amount of sun/charging time to recharge battery bank). GEL's typically have a 5% maximum rate of charge, or the battery can be permanently damaged. Not great when you want to get power back into a battery quickly (limited sun/generator backup fast to limit noise, wear and tear, fuel costs).
Again--I am no expert. I have a grid tied system. Just what I have gleaned from my limited experiences with batteries, reading FAQ's, and typing here.

Lay out your requirements, then see (and/or discuss here) which meets your needs. Even flooded cell batteries have a wide range of prices and designs (from solar RE to Forklift/Traction Batteries).

Forklift batteries can last 20+ years. However, they require more water and are less efficient at charging. Plus they have higher self discharge (especially as they get old).

AGM's are 90-98% efficient (vs ~80-90% efficient for flooded cell), no water needed, clean. Plus they have very high surge current capabilities (used in UPS's where you can have C*4 discharge rates vis the typical C*0.4 maximum surge rate recommended for standard flooded cell batteries).

It all depends on your needs (and price point).

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 32
Re: setting up my solar panel system to run my pump!

im looking into agms

but will it stop working if it gets overpowered like gel batteries?