25W of solar panel question

[Mike90250]

Who'd 'ave thunk a 25W panel would get a thread this big?

[hay4man]

lsy388, I think we need you to clarify whether your LED's and fan will be consuming 5W or 50W.

It would also be nice if you could tell us the specifications for your 25W panel, or give us a part number or something.

[lsy388]

i got it now, for stable and safety purpose, i need to put at least 320W of solar panel to support my 320wh led light, am i right? By the way, usually what is the average of recharge time for a watt? Thanks.

[greenHouse]

Thanks, will try not to post again.

I still think that he means that all 8 LED together have 5W and not 50W.

I also understand that the panel is working on 12V, anything else doesn't make sense.

If it's not like that I apologize about the BS

Batteries can't be trickled charged from "dead". There are minimum charging rates to bring a battery back to "full". Additionally, batteries really need to be chosen carefully, you can't just get a car battery and try to make it work. Sure, you can replace the battery every two years, but a proper solar system battery can be made to last 5, 10, 20 or more years. Who wants to replace batteries all the time?

In the OP's case, they've not stated the operating parameters of the solar panel. So all of this is just guessing.

Solar power systems need to be =designed= and not just thrown together. And that even applies to little systems that are just providing power for a few LEDs and a fan. For a 25 watt array on a 12 volt system, the largest practical battery is going to be between 25 and 50 amp-hours. 50 amp hours is really pushing it as the maximum charging rate is going to be about 3% of capacity (25 watts / 15 volts = 1.67 amps, 1.67 amps / 50 amp-hours is about 0.033) So, a 25 amp hour battery is a much better choice.

[ecusolar]

Thanks, will try not to post again.

I still think that he means that all 8 LED together have 5W and not 50W.

I also understand that the panel is working on 12V, anything else doesn't make sense.

If it's not like that I apologize about the BS

You're talking BS.

[ecusolar]

Maybe we should take the time to read the posts with enough attention, I wrote:

That's easy if it's right that all LEDs together have 5W.

You are forgetting the the 50W LED draw, for 10 hours, that's 500Whours.

This is an impossible situation. You cannot draw 500WH out of any battery, and replace with 25W x 5 hr = 120WH recharge.

The most the 8 LED 's can run, nightly, is .8hr. There are losses recharging the battery, so the solution is larger PV panel or less lighting.

I do agree with the least expensive battery, instead of buying a 40ha battery, get the cheapest battery, which might be a 60ah, but beacuse it's a common auto battery, mass production makes it cheap.

[Mike90250]

What about i put 50W of solar panel and reduce led duration working time to 8 hour, is that ok with that? Kindly advice. Thanks.

Still not enough. 250wh can't replace 350Wh

A 25W panel is just not very useful for much more than a couple of LED's.

[greenHouse]

Hey Mike, let me know if I'm talking BS but a small thing like this doesn't need to many science I think.

It's almost like triggle charging and discharging.

You're talking BS.

The OP has yet to say when the open circuit voltage of his solar panel is going to be. And it almost sounds like he's making some non-standard voltage panel -- like 25W at 2.5 volts.

Batteries can't be trickled charged to make them full. The self-discharge of a battery is high enough that a too-small solar panel will never recharge the battery. And if the voltage isn't high enough to begin with, it will never recharge the battery.

[lsy388]

What about i put 50W of solar panel and reduce led duration working time to 8 hour, is that ok with that? Kindly advice. Thanks.

[Mike90250]

You are forgetting the the 50W LED draw, for 10 hours, that's 500Whours.

This is an impossible situation. You cannot draw 500WH out of any battery, and replace with 25W x 5 hr = 120WH recharge.

The most the 8 LED 's can run, nightly, is .8hr. There are losses recharging the battery, so the solution is larger PV panel or less lighting.

I do agree with the least expensive battery, instead of buying a 40ha battery, get the cheapest battery, which might be a 60ah, but beacuse it's a common auto battery, mass production makes it cheap.

[lsy388]

Thanks Mike......, i got it now, i am really a SUPER beginner.......,thank you very much.

[ecusolar]

That's easy if it's right that all LEDs together have 5W.

Get you a cheap new car battery, one of those 3 cil. Suzuki cars, I think they have about 45Amps.
With that load you won't deep circle it as you will only discharge about 10% of the capacity. Why buy a deep circle battery when you can get these for some bucks, in case that it get damaged in 2 years or so, just buy a new one.
Than get you this controller .
Connect your 25W panel, the battery and your load (the LEDs).

5W x 10h= 50W/h, the cheap car battery has 12V x 45Amps = 540W

Your panel has 25W and let's say you have 3 hours of enough light to charge, that's 75W, some power will get lost in the way but you will not lose that much that you don't have enough charge for the night.

Hey Mike, let me know if I'm talking BS but a small thing like this doesn't need to many science I think.

It's almost like triggle charging and discharging.

Thanks, ok, my specific question about my project as following;
* ? watt of solar panel > ? volt of charge controller > ? volt of battery > 5W
of led light with 8 nos.(10 hour working only night)

That's my project line, would you please kindly design for me, thanks for your help.

[lsy388]

Thanks, ok, my specific question about my project as following;
* ? watt of solar panel > ? volt of charge controller > ? volt of battery > 5W
of led light with 8 nos.(10 hour working only night)

That's my project line, would you please kindly design for me, thanks for your help.

[ecusolar]

Need more info

Isy, actually I would start to think about what you want to lightnen, move or use with your panels and for how long in which time of the day and with that we can give a valued opinion.

Only saying I have a 25W panel makes no sense without Volt / Amps values as you can't almost do nothing with it other than move a small water fountain or charge a motocicle battery. You have to know that with any energy you convert you will lose some because of heat.

When you need to go through a charge controller, later a battery and at the end an inverter there is not much left of your 25W.

Thanks, actually i just don't understand to convert Watt to Volt, on top of that, i also have no idea how many volt of solar panel will take how long of time for charging certain capacity of battery. As my country is in Malaysia, the capacity of sun heat is fantastic, would you pls kindly instruct me about above question? Thank you very much.

[lsy388]

Thanks, actually i just don't understand to convert Watt to Volt, on top of that, i also have no idea how many volt of solar panel will take how long of time for charging certain capacity of battery. As my country is in Malaysia, the capacity of sun heat is fantastic, would you pls kindly instruct me about above question? Thank you very much.