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**bobinator1420** · 08-22-2012, 04:32 PM

Really? No help?

**inetdog** · 08-22-2012, 05:56 PM

Originally posted by bobinator1420

heyo!!!

I'm pretty new to solar panels and just wanted to know the following

With multiple panels, which is better: hooked up in series or parallel?

Also, i plan on fooling around with some tiny 2V, 0.2 W panels. If i were to hook up about 30, i 'd only be producing around 7W. However, the V would be around 60V. Could this damage a battery setup of 24V?
or would I need to buy a solar controller to run the panels through? Please and thank-you

A 2 volt unit is indeed likely to be multiple cells in series assembled into a panel, but .2 watt is the sort of thing you might find in a solar outdoor light or the like. Pretty much useless for anything serious.
But since you ask, 2 volts is too low a voltage to do anything useful except to run an LED directly or charge a single 1.x volt battery. So you would have to put them in series. The current for 2v, .2 watt would be 100ma. Also too low to be useful for most purposes. So you would have to put your series strings in parallel or your parallel units in series.
At that point it depends on what you are trying to use them for.

As a general question, with panels like 200 watt, whether you hook them up in series or in parallel depends on what the voltage and current of the panels are and what you are planning to use them for.

**MarineLiner** · 08-22-2012, 09:57 PM

Cells and panels

Originally posted by inetdog

A 2 volt unit is indeed likely to be multiple cells in series assembled into a panel, . . . . .

Thank you.

I write it again:
¤ A 2 volt unit is indeed likely to be a cell
¤ multiple cells in series assembled into a panel

Then, we can make two strings of 15 cells in series which will have 30 volts each. The current still the same.
Next, we connect those 2 strings by parallel. The current increase.
If we want to make 28 volts then use only 14 cells in each string.

**inetdog** · 08-22-2012, 10:40 PM

Originally posted by MarineLiner

Thank you.

I write it again:
¤ A 2 volt unit is indeed likely to be a cell
¤ multiple cells in series assembled into a panel

Then, we can make two strings of 15 cells in series which will have 30 volts each. The current still the same.
Next, we connect those 2 strings by parallel. The current increase.
If we want to make 28 volts then use only 14 cells in each string.

A typical silicon monocrystaline cell will have a voltage around .6 volts. So a 2 volt unit will be 3 or 4 of those cells in series, making a mini-panel.

**MarineLiner** · 08-23-2012, 12:01 AM

Originally posted by inetdog

A typical silicon monocrystaline cell will have a voltage around .6 volts. So a
2 volt unit will be 3 or 4 of those cells in series, making a mini-panel.

OIC. So, what we can do is connecting those mini panels in series and make them into two strings of the same units (14 or 15) as i post before.
Then connect those two strings of mini panel in parallel to increase it's current.
But still 7 watts is so "small" and has only a limited usage.
Or maybe the battery is for laptop?

**inetdog** · 08-23-2012, 01:34 AM

Originally posted by bobinator1420

heyo!!!

I'm pretty new to solar panels and just wanted to know the following

With multiple panels, which is better: hooked up in series or parallel?

Also, i plan on fooling around with some tiny 2V, 0.2 W panels. If i were to hook up about 30, i 'd only be producing around 7W. However, the V would be around 60V. Could this damage a battery setup of 24V?
or would I need to buy a solar controller to run the panels through? Please and thank-you

Continuing:

30 of those in series would be 60 volts, but still only .2amp. So the extra voltage ability will be wasted running into a 24 volt battery.
On the other hand, with or without a controller .2 amps will not overcharge (or even properly charge) an FLA battery of more than about 10 amp-hour capacity.
For long term float charging, you do need to regulate the voltage.
For other types of battery such as Li-ion, a charge controller is absolutely necessary for safety as well as for preserving the battery.

**MarineLiner** · 08-23-2012, 02:19 AM

Originally posted by inetdog

Continuing:

30 of those in series would be 60 volts, but still only .2amp. So the extra voltage ability will be wasted running into a 24 volt battery.

That's right.
And it's why i proposed to build two 28v strings by connecting 14 of those in series. So the extra voltage will be enough just to charge 24 volts battery.
By connecting those two 28 volts strings on parallel, we get 0.4 amp.
Your thought?

**bobinator1420** · 08-23-2012, 03:19 PM

Originally posted by MarineLiner

OIC. So, what we can do is connecting those mini panels in series and make them into two strings of the same units (14 or 15) as i post before.
Then connect those two strings of mini panel in parallel to increase it's current.
But still 7 watts is so "small" and has only a limited usage.
Or maybe the battery is for laptop?

So I guess I should use the same number of cells but put 1/2 in series the. Hook that up in parallel? And it's not for a laptop but an application similar to topping of the charge on a 36 v battey composed of 3 12v (10aH). Think like an Rv or boat same concept

**green** · 08-23-2012, 06:21 PM

Originally posted by inetdog

For other types of battery such as Li-ion, a charge controller is absolutely necessary for safety as well as for preserving the battery.

What if you charged a 3.4V cylinder Li-ion with one of these 5v 200MA mini panels without a controller? I was thinking of doing this for a project. That's not enough to make it go boom

is it?

**MarineLiner** · 08-23-2012, 09:45 PM

Originally posted by bobinator1420

And it's not for a laptop but an application similar to topping of the charge on a 36 v battey composed of 3 12v (10aH). Think like an Rv or boat same concept

Wait a minute¡

You said before it's 24 volts?
Why not telling about 36 volts?
Let's wait what inetdog will say?

**inetdog** · 08-24-2012, 12:06 PM

Originally posted by green

What if you charged a 3.4V cylinder Li-ion with one of these 5v 200MA mini panels without a controller? I was thinking of doing this for a project. That's not enough to make it go boom

is it?

It is remarkably easy to make any Li-ion battery go boom, even when you use a charger made for it. Connecting any Li-ion battery directly to a power source such as a panel (even your 5 volt 200ma mini panel) is not a good idea. You may get away with it because of the low current limit, but an Li-ion battery will lose life and possibly become unsafe (go boom from internal short-circuit) if constantly overcharged, even at a low rate. Other battery types such as NiCd and NiMH are much more tolerant in this respect. Li-ion chargers do NOT include a trickle charge mode.

There is a good detailed description of Li-ion battery chemistry and characteristics here.

**inetdog** · 08-24-2012, 12:21 PM

Originally posted by bobinator1420

So I guess I should use the same number of cells but put 1/2 in series the. Hook that up in parallel? And it's not for a laptop but an application similar to topping of the charge on a 36 v battey composed of 3 12v (10aH). Think like an Rv or boat same concept

The amount of power you get, if you optimize the series/parallel configuration, would be reasonable for topping off or floating a 36 volt 10 AH battery stack. But a lot would depend on the details of the 12 volt batteries (FLA, AGM, or GEL). For a low AH capacity situation like that, 7 watts is still too low to do any major charging. For maintenance of batteries that would be unattended and unused for long periods of time, it would be a reasonable application, I think.

**green** · 08-24-2012, 01:20 PM

I guess I'll skip the Li-Ion project. But I do actualy have a small homemade trickle charger that is maintaining a 12V 12AH SLA battery. I took the cells from 12 solar landscape lights, wired them as 2 strings of 6. I forget the Numbers I was getting but it was like 20V at 500mA or something like that. Anyways that runs a small portable police scanner that I got sick of changing 6 AA's at a time in. The scanner uses 9V so there is a 12VDC-9VDC wired in between. I have no charge controller hooked up, just a blocking diode. I've had it hooked up a little over a month and it keeps the battery right at 12.6V. I'm happy with it.

Oh I should say the scanner is only on maybe 20 to 30 mins a day, But it does use power when it's idle to maintain memory.

**bobinator1420** · 08-24-2012, 11:31 PM

Originally posted by inetdog

The amount of power you get, if you optimize the series/parallel configuration, would be reasonable for topping off or floating a 36 volt 10 AH battery stack. But a lot would depend on the details of the 12 volt batteries (FLA, AGM, or GEL). For a low AH capacity situation like that, 7 watts is still too low to do any major charging. For maintenance of batteries that would be unattended and unused for long periods of time, it would be a reasonable application, I think.

I think it is a reasonable application then. Thanks. Oh and would I still need a voltage regulator (see link below) like this for that kind of application? Or can I directly hook up the panel to the battery system? And they are simple lead acid based rechargeable batteries.

http://www.amazon.com/gp/aw/d/B000FIWKQE/ref=aw_ls__1?colid=2AR2G8IGQG44J&coliid=I13YSHVLOZJ4CD

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