panel for 130 amp battery

[jony lima]

5W / 12V = 0.42 amps
Run time till battery :
30% depleted 5.8 hours (5.74 amps remaining)
50% depleted 9.7 hours (4.1 a remain)
stop now and recharge
100% (0A remain, you have destroyed the battery, recycle and buy new one)

Because of battery losses and such, recharge with a 10 w panel, will take about as long as the 5w fan runs. That means, if you only have 5 good hours of solar light a day (this is very much shorter than dawn - sunset) you can only run the fan for 5 hours, or you will not be able to recharge fully the next day. After 2 days of not fully recharging, you destroy the battery, and it's going to be time to buy a new one.

thanks
so do i need 20 watt panel? or battery of more Amps? i just want to run the fan 6 hours
jony

[Mike90250]

5W / 12V = 0.42 amps
Run time till battery :
30% depleted 5.8 hours (5.74 amps remaining)
50% depleted 9.7 hours (4.1 a remain)
stop now and recharge
100% (0A remain, you have destroyed the battery, recycle and buy new one)

Because of battery losses and such, recharge with a 10 w panel, will take about as long as the 5w fan runs. That means, if you only have 5 good hours of solar light a day (this is very much shorter than dawn - sunset) you can only run the fan for 5 hours, or you will not be able to recharge fully the next day. After 2 days of not fully recharging, you destroy the battery, and it's going to be time to buy a new one.

[jony lima]

Read up on charge controllers here

http://www.windsun.com/ChargeControls/ChargeCont.htm

In a car, the battery generally does not get run down so much that it needs special attention to being recharged. but in off grid use, the batteries get cycled deep enough and often enough, that they greatly benefit from 3 stage charging.

As to the motor, you must first determine how much it will run, and then size the battery, and then the panel for recharging.

5 watts for 10 minutes a day, is very different than 5 watts for 18 hours a day
assume a 12V system, 5 watts is 0.41 amps

yes Mike,
but which i tried to ask u that how long hours i can run my 5 watts motor consuming 50% discharge the 8.2 Amp battery. and can i charge the battery with 10 watt panel?
thanks
jony

[Mike90250]

Read up on charge controllers here

http://www.windsun.com/ChargeControls/ChargeCont.htm

In a car, the battery generally does not get run down so much that it needs special attention to being recharged. but in off grid use, the batteries get cycled deep enough and often enough, that they greatly benefit from 3 stage charging.

As to the motor, you must first determine how much it will run, and then size the battery, and then the panel for recharging.

5 watts for 10 minutes a day, is very different than 5 watts for 18 hours a day
assume a 12V system, 5 watts is 0.41 amps

[jony lima]

thank u mike,
i learn about 3 stage charge controller. if i use deep cycle lead acid battery, is it mandatory to use 3 stage controller? another question is- i have a 5 watt small motor. can i run it with 8.2 amp sealed acid battery and charge with 10 watt panel?

thanks
jony

[Mike90250]

3 stage controllers have BULK, ABSORB and FLOAT modes.

Many good ones have selector switch for AGM, GEL or FLOODED batteries. Only Flooded batteries can be EQUALIZED.

Controller info http://www.windsun.com/ChargeControls/ChargeCont.htm

Morningstar makes a good line, as does Outback, and Xantrex
http://www.solar-electric.com/mochco.html morningstar products.

You have to read the fine print to make sure the controller you select, will do what you need.

Lots of cheap ones from China, but quality is unknown.

[jony lima]

Adding in the inverter losses, of 20%, and a slight correction on your math: 310 watt hours, you will consume about 372wh daily.

If used in the sunny part of the day, the solar panel will provide some power directly, you may only need 100W of panels.

if at night, in the dark, you will need more panel, to compensate for battery recharge losses. 200W would be a good start.

For a 24 hour cycle, you need a battery with 800Wh storage, at 12V, that's a 66Ah battery. Common sizes are 50-90ah, so you should be OK. If you can't find a true DEEP CYCLE battery, 2, 6V golf cart batteries would work.

Don't use a car or truck battery, it will fail on you in a month. It needs to be a deep cycle battery.

You will also need a 3 stage charge controller. If it does not state 3-stage on it, don't get it.

If you expect a cloudy day, you need to double the battery size, so it does not sit discharged and get ruined. If you expect 2 or more cloudy days, you MUST get a grid power charger, to recharge the battery so it does not sit discharged. Going to an even larger battery, you gain nothing, because the solar will not be able to recharge it before the battery is ruined.

thank u Mike
u r great. can u tell me what is 3 stage controller? and can i use seal acid battery for it?
thanks
jony

[Mike90250]

Adding in the inverter losses, of 20%, and a slight correction on your math: 310 watt hours, you will consume about 372wh daily.

If used in the sunny part of the day, the solar panel will provide some power directly, you may only need 100W of panels.

if at night, in the dark, you will need more panel, to compensate for battery recharge losses. 200W would be a good start.

For a 24 hour cycle, you need a battery with 800Wh storage, at 12V, that's a 66Ah battery. Common sizes are 50-90ah, so you should be OK. If you can't find a true DEEP CYCLE battery, 2, 6V golf cart batteries would work.

Don't use a car or truck battery, it will fail on you in a month. It needs to be a deep cycle battery.

You will also need a 3 stage charge controller. If it does not state 3-stage on it, don't get it.

If you expect a cloudy day, you need to double the battery size, so it does not sit discharged and get ruined. If you expect 2 or more cloudy days, you MUST get a grid power charger, to recharge the battery so it does not sit discharged. Going to an even larger battery, you gain nothing, because the solar will not be able to recharge it before the battery is ruined.

[jony lima]

Cost wise, you will fare better with just a battery, inverter and grid powered charger, solar will easily add 700 $ us to the cost, a battery charger from the auto parts store is $100 (for a good 3 stage charger)

thank u Mike

but i like to build a solar system for load shedding. can u give me the configuration?

1 fan for 3 hours=80*3=240 watts.
3 CFLs=23*3=69 watts
total load=300 watts aprox. per day.

jony

[Mike90250]

Cost wise, you will fare better with just a battery, inverter and grid powered charger, solar will easily add 700 $ us to the cost, a battery charger from the auto parts store is $100 (for a good 3 stage charger)

[jony lima]

need to know

hello all,
I like to build a solar system which will run 3 to 4 Hours. my load is a fan/80watts and 3 lights (23 watts*3) 70 watts. i will run it when electricity fails. here average load shedding is 2-4 hrs daily. can u tell me what would be my battery bank and panel watt?
my area is Dhaka, Bangladesh.

thanks
jony

[jony lima]

Well there is some fact and fiction with 10% charge current. PWM and MPPT charge controllers are very different animals.

With PWM CC the Input current = Output current so if you wanted to say run a 12 volt @ 130 Amp Hour battery with a C/10 charge current (10%), you would have to select a solar panel with a Imp (current maximum power) or 13 amps. 13 is 10% of 130 right? However what wattage is that panel. Who knows it is not specified. With most 12/24 volt PWM charge controllers the maximum Voc (voltage open circuit voltage) can be as high as 55 volts, which means the Vmp (voltage maximum power) is around 42 volts. On the low end if you were to use a panel made for 12 volt battery system the Vmp = 17 volts. So what size panel would one need to supply 13 amps to a 12 volt battery system. Answer is anywhere from 220 to 550 watts. Quite a range huh?

Here is where it gets educational. The panel size for a MPPT controller needed to supply 13 amps to a 12 volt battery is 170 watts period. Think about that for a while and what it means.

The key to the mystery is the current, for PWM the panel Imp determines the current. For MPPT the panel wattage and battery voltage determines the current.

So to answer your question would a 240 watt panel work with a PWM CC. Beats me, what is the Vmp & Imp of the panel? If the Vmp = 16 to 18 volts, and Imp = 13.3 to 15 amps it will work.

hello Russ
thanks a lot. first i felt difficult to understand ur lesson. i read it several times and now i think i got it.u told me that main thing is current. can u help me that how can i measure the current from a panel by using a digital meeter?

[jony lima]

Charge amps = C/10

hello Sunking,
u might know that i have no academic knowledge about the formula about solar or electrical engineering. but i have much interest to learn this. i like to build some projects. thank u all for helping me. pls make the formula more easy, i mean what is charge amps and c/10 or how can it help me to calculate measuring panel watts?

jony

[Sunking]

thank u
can u give me a easy formula that i can calculate my panel for any amp of battery?

Charge amps = C/10

[jockellis]

Jony, Sunking has often reminded people that they need to remember that you don't set your solar aspirations on the length of sunlight in the longest day but the shortest which would, of course, be in the winter.
Here in America, that time, Sunking points out, would be about four hours because the sun has to be pretty much overhead. I would bet your usable sunlight hours are not too far from ours which would mean way less sun than you anticipate.
Lead acid batteries cannot sustain a loss of over 1/3 their rated amperage and last every long. You may have a number like 95 on your battery. That is a US government, or was, regulation so that buyers would know how much electricity was in that battery. It means that discharging at 12.6 volts and 25 amps that the battery would last 95 minutes. But remember that you can't use but a third of that without killing your battery so it is more like 31 minutes that you could discharge electricity at that rate.