Solar Panel for seldom usage

[Justniv]

Hi everyone,
I'm new to solar&electronic.
The project i want to do is to build a solar panel for camping outdoors. Im gonna use this panel twice a year for a week each time (probably less). so the rest of the it will probably be stored in the basement or something - disconnected and away from the sun.
I want to be able to turn on ~7 led bulbs of 10w, and to charge a portable speaker which draw 0.85A @ 14v (that's what written on the ac/dc adapter: output: 14V 0.85A)
Ive already ordered 40 solar cells of: 0.5V 8A 4W.(here:http://www.ebay.com/itm/350701549614...84.m1439.l2649)
My question is if this low amper battery gonna be good for this purpose:
C12-8.5 Normal Voltage: 12v 8.5Ah 151x65x97 = Datasheet: http://rostec.livesystem.co.il/pictu...181_12v8.5.pdf

For example let's take this bulb: http://dx.com/p/e27-10w-6500k-166-le...ulb-220v-51280
from my understanding it's draw 10W/220V= 0.045A
so 7 like this will draw: 0.32A
and the speaker charger will draw 0.85A.
correct me if i'm wrong.
thanx

[daz]

Welcome to Solar Panel Talk!

Hi everyone,
I'm new to solar&electronic.
The project i want to do is to build a solar panel for camping outdoors. Im gonna use this panel twice a year for a week each time (probably less). so the rest of the it will probably be stored in the basement or something - disconnected and away from the sun.

It is actually cheaper to buy a solar panel, than make one yourself (once you factor amount of time taken, consumables, cells, etc)!

I want to be able to turn on ~7 led bulbs of 10w, and to charge a portable speaker which draw 0.85A @ 14v (that's what written on the ac/dc adapter: output: 14V 0.85A)
Ive already ordered 40 solar cells of: 0.5V 8A 4W.(here:http://www.ebay.com/itm/350701549614...84.m1439.l2649)
My question is if this low amper battery gonna be good for this purpose:
C12-8.5 Normal Voltage: 12v 8.5Ah 151x65x97 = Datasheet: http://rostec.livesystem.co.il/pictu...181_12v8.5.pdf

Well, battery capacity depends how long you want to run the lights for, as well as for how many days backup you need.....

On another note...I assume you got the 40 x 0.5V @ 8A cells to make a 12V nominal panel? If so, theoretically, you should have 20V @ 8A. If you intend to use this on an 8.5AH battery...you are going to have a lot of flames!!! Let's assume the maximum charge rate for your AGM battery is C/4 (I didnt go through to your link yet)....then the minimum size battery you require is a 32AH @ 12V, otherwise your solar panel will overcharge your battery.

For example let's take this bulb: http://dx.com/p/e27-10w-6500k-166-le...ulb-220v-51280
from my understanding it's draw 10W/220V= 0.045A
so 7 like this will draw: 0.32A
and the speaker charger will draw 0.85A.
correct me if i'm wrong.
thanx

That is correct, but remember, that is at 220V. You will need to use an inverter to get 220V, and that means you will be drawing 5.8A on the 12V side (so your little 8.5AH battery is inadequate).


What I would recommend, is you first have a look at the 'stickies' in the off-grid section of the forum first. Once you have read them a good few times, then fire away your questions. The stickies will give you a much better idea of what is required, as well as a look at the costs involved!

[Justniv]

thanx

It is actually cheaper to buy a solar panel, than make one yourself (once you factor amount of time taken, consumables, cells, etc)!

i'm not from the US so the shipment is expensive, plus taxes & customs.

Well, battery capacity depends how long you want to run the lights for, as well as for how many days backup you need.....

something like 6 hrs, for 4 days...(working only at night of course - 20:00-2:00)

If you intend to use this on an 8.5AH battery...you are going to have a lot of flames!!! Let's assume the maximum charge rate for your AGM battery is C/4 (I didnt go through to your link yet)....then the minimum size battery you require is a 32AH @ 12V, otherwise your solar panel will overcharge your battery.

i'm planing to use a charge control, like this: http://www.ebay.com/itm/Solar-Charge...item27d409d647
isn't it gonna solve the issue of over charging??

That is correct, but remember, that is at 220V. You will need to use an inverter to get 220V, and that means you will be drawing 5.8A on the 12V side (so your little 8.5AH battery is inadequate

I'M planning to use an inverter, but didn't check this area yet...so i didn't understand u when u wrote:

and that means you will be drawing 5.8A on the 12V side (so your little 8.5AH battery is inadequate).

[daz]

thanx

No problem!

i'm not from the US so the shipment is expensive, plus taxes & customs.

I am not from the USA either....but even here, it's cheaper to just buy the solar panels than to make them yourself.

The only times it would make sense to make a solar panel is;
1) you want to learn (ie its a hobby and not for real world reliable application),
2) you have absolutely no access to solar panels in your country (or the solar panels are extremely expensive)

Remember, homemade solar panels won't last as long as commercially manufactured solar panels. Also, a lot of homemade panels are not very reliable (some even catch on fire, for bad designing!).

Where abouts are you from/looking to install a solar system?

something like 6 hrs, for 4 days...(working only at night of course - 20:00-2:00)

Ok, assuming you are still going with the 7 x 10W lights;
7 x 10W = 70W x 6 hours = 420WH per day
420WH / 12V = 35AH
So you need an absolute minimum battery capacity of 70AH @ 12V, or a recommended capacity of between 120AH - 200AH @ 12V (<--- with no reserve days)

i'm planing to use a charge control, like this: ******* . isn't it gonna solve the issue of over charging??

A charge controller controls the charging voltage, not the charge current. The charge current is controlled by using the correct size solar panel. So you have to size the solar panels according to the battery.
If the solar panel wattage is too high for the battery, the battery will be irreversibly damaged. Likewise, if your solar panel is too small, your batteries might get sulphated for insufficient charge.

PS..that charge controller you linked to is a PWM. PWM controllers are only 65% efficient, which means you need a bigger solar panel to make up for the loss in efficiency.

I'M planning to use an inverter, but didn't check this area yet...so i didn't understand u when u wrote:

The inverter takes 12V in, and puts out 220V. The current out on the 220V side will be 1/18th of the current that the inverter draws from the battery side.
For example, lets say you needed 50W out from your inverter (@220V), the inverter will draw; 50W / 12V = 4.2A from the battery.
So 50W @ 12V = 4.2A
At 220V, 50W = 0.23A (50W / 220V = 0.23A)

Does that help?

[Sunking]

You would be throwing a lot of money away doing what you want. There is a much simpler less expensive way to get it done. Just get a good deep cycle battery and float battery charger. If you do it your way not only will you have a panel and charge controller, you will also need th efloat charge to keep the battey maintained and charged up when you put the panel in the garage. Just eliminate the expense and trouble. A good deep cycle battery will run th ecamp fopr several days without a recharge. If in trouble just hook up a set of jumper cables to car battery and run the engine for a few minutes. You have no use for the panel.

[Justniv]

sorry for the delay..

Just get a good deep cycle battery and float battery charger

you mean somthing like this: http://www.ebay.com/itm/12V-Automati...ht_2302wt_1093

?
and what about inverter dc/ac??

So, daz calculated it and im gonna be using 420W a day. lets say i want it for 3 days- 420W*3= 1260W. now from here im not sure how to continue because of the inverter, so just a "draft"
1260W/220 = 5.72Ah
or
1260W/12 = 105Ah

And let's not forget because it's deep cycle it's not recommended to discharge it more than 50%, so:
105Ah*2 = 210Ah--->> ~250Ah (just incase...)
or
5.72Ah*2= 11.44Ah--->> 20Ah

thanx

[daz]

So, daz calculated it and im gonna be using 420W a day. lets say i want it for 3 days- 420W*3= 1260W. now from here im not sure how to continue because of the inverter, so just a "draft"
1260W/220 = 5.72Ah
or
1260W/12 = 105Ah

And let's not forget because it's deep cycle it's not recommended to discharge it more than 50%, so:
105Ah*2 = 210Ah--->> ~250Ah (just incase...)
or
5.72Ah*2= 11.44Ah--->> 20Ah

thanx

Check there in bold, that is the correct one (because you are using batteries)...

Also, inverters are never 100% efficient, so you need to cater for that as well. Assuming your inverter was 85% efficient, you need to add an additional 15% for losses. So 1260WH + 15% = 1449WH
1449WH / 12V = 120.75 --> 121AH @ 12V

So if you require 121AH @ 12V, the absolute minimum battery capacity you would need is 242AH @ 12V (for a 50% DOD). Round up to next available size, perhaps a 250AH @ 12V?
Also, try to get one big battery instead of two smaller ones, as that will be much better! If all else fails, and you cannot get one big battery, only then look at using 2 smaller batteries (ie 2 x 130AH @ 12V).

[Sunking]

sorry for the delay..


you mean somthing like this: http://www.ebay.com/itm/12V-Automati...ht_2302wt_1093

?
and what about inverter dc/ac??

No I said a good Float Charger like Iota DLS 30.

What do you need an inverter for? There are lots of them available at good prices. Just do not the common mistake of buying one too large.

[Justniv]

is this gonna be good as inverter?

http://www.ebay.com/itm/BESTEK-300-WATT-Car-Power-Inverter-Charger-Adapter-With-USB-DC-TO-AC-Computer/390573457210?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D261%26meid%3D8725283664759152230%26pid%3D100005%26prg%3D1088%26rk%3D5%26sd%3D290895258976%26

what do i need to know/search on the inverter?
obviously 12v->220
150W will be enough
efficiency = the more the better- around 85%
what about Amperage ?
Protection?

* so in all of the calculations i only refer to 12V and basically ignoring the 220V?
*about the charger, it stops charging when battery is full?
*how many years will this arrangement last for?
* is there a simple way to know how much the battery discharge?

******** EDIT ****
i didnt see your post before
the DLS 30 is very expensive! isn't there is somthing cheaper?

What do you need an inverter for?

to light up 7 led lamp (220V), and to charge a portable speaker (which has a lithium battery inside)

[Sunking]

so in all of the calculations i only refer to 12V and basically ignoring the 220V?
*about the charger, it stops charging when battery is full?
*how many years will this arrangement last for?
* is there a simple way to know how much the battery discharge?

You are going about this kind of all wrong. You are basically hoping it will work, rather than designing it to work.

Step one is determine daily watt hour usage. From that you then determine battery autonomy (days of use before recharge), solar panel wattage and charge controller size if used and/or battery charger.

So lets say you skip solar and will use 300 watt hours per day, and will be out for 3 days. Immediately you know the battery size. It needs to have 6 days reserve capacity or 300 wh x 6 days = 1800 watt hours. To find the AH = WH / Battery Voltage. So let's say 12 volts. You need 1800 wh / 12 volts = 150 AH battery @ 12 volts. Now you can sleep well at night knowing you have a battery that can supply 300 wh/day for 3 straight days and even 4 or 5 if push come to shove. Get an AGM and as infrequently as you will use it can go 5 days. An AGM battery if used or not will last about 2 or 4 years depending on quality, how deeply discharge, and frequency of use.

For a charge either it be solar or a commercial AC needs to provide a C/10 hour charge rate for your application where C = the battery AH capacity. So if using a 150 AH battery 150 AH / 10 H = 15 amps. To do that with solar if you use a inexpensive 15 amp PWM controller will require two expensive 135 watt 12 volt battery panels (270 watts), or use a more expensive MPPT charge controller with one inexpensive 190 watt grid tied panel.

If it were me with your application I would just buy a properly sized battery and battery charger, and take some jumper cables with me to charge the battery up at camp from a vehicle if I get in a pinch by running the motor for 15 minutes. Then I do no thave to waste my money of the solar junk and lug all that crap around to use twice a year. Besides to use solar at a camp site means a clear cut area with full view of the horizon. That does not sound like a very nice camp site to me, an dhere in TX you would roast in the sun.

[Justniv]

Ok i didn't made my self clear at the last message - i DO wanna listen to your advice and just use a battery WITHOUT SOLAR.
you say that i only need a battery and a charger. And i'm wondering what about an dc/ac inverter? because my goal is to turn on led bulbs and to charge a portable speaker. so i found those "light bulbs" which can work:

http://www.ebay.com/itm/10W-LED-Flood-Light-White-High-Power-Waterproof-Outdoor-Wash-Lamp-Bulb-DC-12V-/370825054478?pt=LH_DefaultDomain_0&hash=item5656e5490e

And

http://www.ebay.com/itm/New-10W-900lm-LED-Spotlight-Flood-spot-Light-Lamp-Bulb-Cool-White-DC-12V-85-265V-/130767057538?pt=US_Light_Bulbs&var=&hash=item1e7252f282

they are DC. but about charging the portable speaker? (it's also charge with DC current but with an adapter that gets: 220V and Outputs: 14V 0.85A). if it's getting problematic with the speaker (12V -14V) i'm not gonna use it...

* about the charger - the DLS 30 you gave as an example is for 400W 30A, is that good? too much? is there other cheaper charger?
* why did you pick AGM battery and not FLA? (i did read the sticky thread about batteries..)

[Sunking]

Ok i didn't made my self clear at the last message - i DO wanna listen to your advice and just use a battery WITHOUT SOLAR.
you say that i only need a battery and a charger. And i'm wondering what about an dc/ac inverter? because my goal is to turn on led bulbs and to charge a portable speaker. so i found those "light bulbs" which can work:

http://www.ebay.com/itm/10W-LED-Flood-Light-White-High-Power-Waterproof-Outdoor-Wash-Lamp-Bulb-DC-12V-/370825054478?pt=LH_DefaultDomain_0&hash=item5656e5490e

And

http://www.ebay.com/itm/New-10W-900lm-LED-Spotlight-Flood-spot-Light-Lamp-Bulb-Cool-White-DC-12V-85-265V-/130767057538?pt=US_Light_Bulbs&var=&hash=item1e7252f282

they are DC. but about charging the portable speaker? (it's also charge with DC current but with an adapter that gets: 220V and Outputs: 14V 0.85A). if it's getting problematic with the speaker (12V -14V) i'm not gonna use it...

* about the charger - the DLS 30 you gave as an example is for 400W 30A, is that good? too much? is there other cheaper charger?
* why did you pick AGM battery and not FLA? (i did read the sticky thread about batteries..)

If everything you use is 12 volt DC, you do not need an inverter. I recommended AGM for two reasons.

• Portable
• Can be discharged to 50% DOD without major loss of cycle life.

The charger I recommend was an example of a good quality charger. The actual size needs to be about 10% (aka C/10) of the battery AH capacity. So if you have a 200 AH battery you are looking for a battery charger around 20 amps. Anything from 15 to 25 is OK.

[Justniv]

Thank you very much!
now i need to find what to do with the solar cells i've ordered :\