Voltage stepping small panel help please!

[zabanikopek]

Hello all.

Glad to have found this community http://www.solarpaneltalk.com/images...on_e_smile.gif
I have a small workshop and help with community projects on solar, gray water systems etc as the 'green industry' in the UK seems to be very expensive.

I want to make a small panel using 4 x 4w 6 inch cells just to charge phones/mp3 players just for camping trips etc with a cigarette lighter socket.

I realize the panel will be putting out 2v and would like to ask help what I need to add to get it up to a useful voltage.

I'm a novice so any advice would be very much appreciated.

[Sunking]

That voltage is not going to work, you will have to go up to around 7 to 9 volts.

[zabanikopek]

Thank you Sunking

A better question would have been....

I wish to make a small panel from scratch about a 1ft x 2ft to charge mp3's, phones, ipods....Where would be a good place to start?

I can source 6"x6" 4w cells locally...

Thank you for replying....

[Mike90250]

You would need a 2v DC - DC convertor, to step it up, but they don't really make things like that, till you get to about 5V DC input power. Hey - that's USB voltage, so you need to increase your PV to about 5.5V @ 1A to use USB chargers. (that's about 7w of PV panel, about a foot square.)

[Perry]

Hello all.

I realize the panel will be putting out 2v and would like to ask help what I need to add to get it up to a useful voltage.

I'm a novice so any advice would be very much appreciated.

Does each cell put out 0.5 volts or 2 volts?

[Mike90250]

each PV cell puts out 0.5V, so you would need at least 10 cells in series to get 5V.

[Sunking]

You have three challenges to over come.

1. In theory you can build a DC to DC converter to step up the voltage. It is done in many products by Switch Mode conversion which is where you take the DC voltage, convert it to AC, use a transformer to step up the voltage, and rectify it back to Dc voltage. Challenge is you cannot do it with just two volts as it takes more than that to operate the components. However the converter requires a lot of parts and engineering which means expensive unit cost
2. The more practical way is to oversize the panel to say 10 volts at 1 amp or a 10 watt panel. Then use simple linear voltage regulator that only use a couple of convention voltage-current regulators, and only cost a few dollars. Most of the power is wasted as heat but who cares as it works, practical, and some think affordable spending $100 to replace a $5 wall charger that will use 5-cents of electricity in 10 years.
3. Competition. They already exist and are factory made foldaway flexible panels that are light and come with a warranty and listed and certified for the purpose by a listing agency. As a DIY you would never be able to match the price, quality or legal listing fees.

[zabanikopek]

Point taken

Many thanks

It was just an idea for a simple 1 day group workshop for people with limited ability to teach some basics and have something to take away at the end of the day without having to wire up 36 cells and encapsulate a whole panel.

[cs1248]

Cost of cells?

Point taken

Many thanks

It was just an idea for a simple 1 day group workshop for people with limited ability to teach some basics and have something to take away at the end of the day without having to wire up 36 cells and encapsulate a whole panel.

If the cells are"dirt" cheap and square and 4 watts cut them in 4 equal peices
This takes skill and you might cut up some broken cells for practice.
You'll have 4, .5 volt cells @ 2a. Properly tabbed and wired, you'll have 8volts @ 2a
in an area just a little over a sq foot.
I use a steel ruler and a "new" utility razor knife and "snap them over a small guage welding rod. Might mention I've had lots of glass cutting experience from my stained glass days. Might also mention, I've got a lot of broken cells.
Wish you a good learning experience.Charles

[Mike90250]

....
You'll have 4, .5 volt cells @ 2a. Properly tabbed and wired, you'll have 8volts @ 2a

I think that actually gives you 2V @ 2A from 4 cells in series. Not 8v.

[cs1248]

Mike's right

I think that actually gives you 2V @ 2A from 4 cells in series. Not 8v.

I reread my post and it was a bit unclear. I meant to say, 4, 4watt cells could be divided to produce 8v. You would have 16 segments. The 16 segments would cover "about a sq ft.
'Z", even for hobbiests it is important to measure your results..for instance, at each step, measure... test your individual cells, or segments, for volrs and amps before you assemble your panel. The cheap digital meters,from harbor freight, here in the U.S., are close to my expensive Flukes. Charles