# Multiple Solar Panels in Parallel

Discussion in 'General Electronics Chat' started by Guest3123, Nov 11, 2014.

1. ### Guest3123 Thread Starter Member

Oct 28, 2014
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"Multiple Solar Panels in Parallel"

Do you think that if you arrange your solar panels in parallel that it would be easier, even on cloudy days to hit your target voltage..?

I mean, what if you had 5,000,000,000 or even 3 solar panels that were rated at 1.0vdc, and you put them outside, arranged in parallel. Would more solar panels all working in parallel, even on a cloudy day give you better chances to hit your target (1.0vdc) voltage?

I don't care about the current (amps), only the voltage.

I'm well aware that the voltage (Vdc) stays the same, but multiplying the current (A & mA) and power (W Watts).

2. ### alfacliff Well-Known Member

Dec 13, 2013
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the brightness of the sun determines both the voltage and current output from the panels. and what good is voltage without current? a better way to hit a tareget voltage would be to series your panels and use a voltage regulator to hold the voltaage down to what you need. as the illumination dims and the voltage drops, you would still have enough more voltage that would be regulated down to what you need. thats why some of my panels were designed to be 18 volts in bright sun, then regulated down to 13.6 to charge batteries.

3. ### Guest3123 Thread Starter Member

Oct 28, 2014
391
19
So using a step up, or boost converter wouldn't work as good or as well as a buck or step down converter. I guess even when it comes to shooting for current too, I guess having more voltage would also allow you to use an adjustable buck boost converter to adjust the current & voltage. I guess your right.

Just wondering.. If my solar panels were rated for only 0.300A each @ 4.5vdc, and I joined them in series (x3 = 13vdc). Could I take the 0.300A and also using the higher voltage, could I turn some of that voltage into a higher current even though my solar panels were rated for 1.5 watt each..? That's mainly why I'm trying to get them in parralel, to get that extra current flow. But was just think that if there were multiple solar pannels all working ot get that 4.5vdc, that they would get it more effectively than using only 1 solar panel to hit the target voltage of 4.5vdc.

4. ### wmodavis Well-Known Member

Oct 23, 2010
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The voltage output of solar panels is relative constant as the solar irradiance varies. The current output is pretty much as variable as the irradiance. But that being said there are calls for both series and parallel operation which varies with the system design requirements. Then if you only care about the voltage you'll get more with a series arrangement.

5. ### wayneh Expert

Sep 9, 2010
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A handy rule of thumb I've seen used in most commercial products is that the panel's open voltage is about double the battery voltage. The panel is loaded to ~80% of open circuit voltage and this is near optimal. A few volts are lost in the regulation and so forth.

You need a fairly large system to justify the cost of using buck/boost regulators. In other words, you could get more power by just buying more PV panel instead of a fancy regulator.

6. ### Lestraveled Well-Known Member

May 19, 2014
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Solar panels are often connected in parallel. You do need an isolation diode on the output of each panel and each must have same voltage profile. Solar panels model best as constant current sources which makes them well suited to operate in parallel.

7. ### Guest3123 Thread Starter Member

Oct 28, 2014
391
19
I did wonder if that was the case.. That it's better or more desirable to put them in parallel. Kinda figured that.. Seeing that they suck at providing current. Not to mention, on top of that, they're "seems to me" pretty expensive. Just trying to get up 1A of current to charge a cellphone would of cost me allot more, if I didn't go to eBay to by my 1.5watt, 0.300A, 4.5vdc Solar panels. Had to buy three of em. So I'm gonna wire & probably solder them up in parallel, and see what happens with a 2.7v - 5.5v @ 1A output boost convert, and see if i can't get a tune out of them.

So.. Hooking 3 of em, with a SB240 Schottky diode (0.5VFD), that I'll get about 4.0vdc from them at about a hair under 1A, which my cellphone only uses about 0.900A of current drawn from my MNKE IMR 26650 batteries. So even if they do go below 4vdc, or even 3.0vdc, I should be fine with the boost converter I bought.

But then again, using them in series might be really good too, seeing that I have a crap load of really nice Buck & SEPIC Converter on they're way. So it doesn't really matter I guess. I'm gonna get what I want no matter what. If I need more solar panels, or if I need to buy a higher voltage solar panel, I guess that's what I'll have to do. Either way, I win.

8. ### ErnieM AAC Fanatic!

Apr 24, 2011
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1,789
Since a solar cell is a current source device saying they "suck at providing current" can be shortened to they "suck."

A string of cells in series is limited by the current output of the weakest cell. A weak cell may be a defect of it can be due to a passing cloud, worker's glove, or just dust on the thing. So put them in parallel for the best current output.

Power electronics works more efficiently when working at a higher voltage as the dc sat losses and the current drop losses are lower. So put in series for higher voltage.

Obviously reality is an engineering compromise between the two.