Solar Cells/Build Panel

Connection in series will increase the voltage (just multiply the voltage of each by the number connected in series), but will not change the maximum current. (The same applies to batteries, fuel cells, thermocouples or whatever).

In series the amps would stay the same, but the total voltage of 10 cells would be 10x that of a single cell.

34point. my main question is if I take will say 10 cells 3x6 [I know the voltage part] and the amp's for one cell is 3.6 If i put these in parallel would it be putting out 36 amp's?they claim they are 1.8 watts each.I think that the amp's are more important when charging a 12 deep cycle battery.

tks

Johnny

GA John & 34.5 - green math doesn't often pan out in the end.

By 'green' math I mean the type done on the back of an envelope when chatting with buddies that can be used to support most anything - the grossly optimistic type.

JohnDG. I know about the voltage part. But I just didn't think that the tabbing wire would carry that much amp's. What I plan to do is use 36 cells to get the 18 volts x 3.6 amp's and then put some cells in parallel to get more amp's in the panel.Putting in diodes were needed. then connect to the buss wire.

tks Johnny

WHEN IS THE BEST SITUATION FOR USING MORE AMPS?

WORRY ABOUT YOUR VOLTAGE </P> TO CHARGE VOLTAGE IN A 12VOLT BATTERY</P> 72 CELLS ,WILL PRODUCE 36 VOLTS MAXIMUM

Is your caps lock stuck?

You don't control amperage, you can only control voltage or resistance. Thats why you are getting so many wonky answers.

I won't insult you by quoting ohms law at you. But perhaps Kirchoff's law might be useful to directly answer your question.

ok, what Im going to do is just wire the 72 in seires ,that will come out 36vdc x 3.6 amps.or could just make 2 panels with 32 cells and put them in parallel, and that would give me 18vdc x 6.2 amps. But I think the 72 in seires is Better.

tks for all the in put, I love CR4, and all the good friendly people here.

Johnny

amperage equals voltage divided by resistance. Amperage is what makes wires hot. Without knowing the resistance, you have no idea how much amperage your cells will produce. Only way to find out is to experiment.

Put in a fuse just in case.

Out of curiosity, is there a circuit diagram in the box these cells came with which would explain all this? Sometimes it is helpful to read the directions.

I suggest that if you wire 72 cells in series that you obtain a good current limiter. otherwise you will let all the smoke out.

I like that, 'otherwise you will let all the smoke out' - not at all a good thing to have happen.

Yusef1. I didn't get the cells yet. with the 72 cells the panel will be only 129 watts.Yes I will be putting in a fuse's ,and diodes. I'll make sure all the smoke stays in, lol.

Johnny

Now you got me thinking about the power.So what Im going to do is to make Two panels 36 cells each and then put them in parallel.So then i'll have 18vdc by about 7 amp's.With diodes and fuses were needed. Sure do like all the different thoughts.Sure dose help out.I use to have my own business doing Plumbing/heating/remodeling,build computers for myself,wired houses,but thats much different then solar cells,.in a way.

tks for all the comments.

Johnny

Unless you have a reason for 18 'nominal volts' - the extra 6 volts - when applied to a 12 volt battery - will increase the current per cell, past the 'ideal point on the cells curve'.

If you do not control the current - (i.e. remove the extra volts) - you will probably wreck the cells and almost certainly push 12 volt battery beyond 15 volts - destroying it.

"More is not better" in this context. Balance is 'better'. As in plumbing - you would not put a pressure booster on a garden hose that's been lying in the sun - to get 'greater performance'.

Given 72/24 is 3, why not make 3 strings and have 3.6 x 3 = ~10.8 amps @ 12 'nominal volts'?

It is the closest configuration to 129.6 "theoretical" Watts you will get into a "nominal" 12 volt load.

A 10 amp charge rate is about right for a 100 Ah battery, though 'deep cycle' can require lower rates. As can 'state of charge' influence the current you want. Check these curves for your batteries.

You might be better off buying another 24 cells and making two 7.2 amp panels.

34points, I will be useing a controler.I didn't buy one yet.After reading what you said about making 3, which dose make ALOT of sence.Im always hearing about car alternators charging and then they say a 12 battery need around 18 vdc to charge it...But to think of it, a battery charger is 12vdc. Dam Thanks. Thats what ill do,buy 24 more cells like you said,then wire them in Par. see it's the little things you forget.

tks 34.

Johnny

Your 12 volt battery needs 14.4 volts for bulk charging from what I read.

Keep in mind the my greatest electrical qualifications are:

1) Telling my electrical engineer what I want

2) Turning the house lamps on and off

Yes.

The other wrinkle is that your cells will not always be putting out the same voltage all the time. Sometimes it will be less. For instance, when the cells are at an angle or when a cloud obscures the sun. So you will need to enough extra cells to continue to charge the battery even in low light conditions. (this is a simplification I know, but it is adequate for this discussion.)

However, too many cells might mean that you will over drive the array in high light conditions. If you have too many cells creating too much voltage, you could warm things up. (let the smoke out...grin!) What you have to then is to limit the voltage or limit the current. One way to limit the voltage would be to drag a curtain in front of the cells. Or electronically cut out some of the cells which would do the same thing. (the mind boggles at the idea of a computer sampling each cell and cutting out underperforming ones! Get rid of that pesky serial thing where if one cell goes down the whole string goes down! I only mention this because I don't think anybody is actually making such a sampler-controller. We have the technology, you could be the first!) Or what is more usual, you could go to the other end, and install a current limiting resistor. In its simplest form a transistor with a high enough current rating would work.

Now we are getting into "circuitry" and here is where the lurkers in CR4 would shine! They can design you a controller. Your controller would simply detect the applied voltage, detect the state of charge of your battery, and adjust the conductivity of the transistor to apply the appropriate charge. Or you could simply buy one. $49.00 would solve all your problems.

BE SURE AND FOLLOW THESE RULES: To increase the amps - you put identical 24 pieces strings in parallel. I.e 2 strings of 24 each = 12 V x 7.2 amps. But when paralleling strings, you must incorporate a 'blocking diode' to prevent strings in light discharging into a string in 'shade' - (less light due to a cloud passing or other shadow on part of the panel) and the battery discharging through the panel. (as they don't like it) So every string is 24 (or whatever number makes up your target voltage) + a diode rated above the Amps expected. (generally a 5A diode for this size of cell) It's up to you to decide if you want an extra cell per string, to make up for the roughly 0.6 V drop of the diode, or you want a higher string voltage for charging reasons - like being 2 V above a regulators output voltage.

This has already been explained in this thread.

hello Saveone. I know about the diode ,and I will put in that extra cell.

again Thanks

Johnny

i don't believe anyone was right because the given information is incomplete and unclear. Cell performance is denoted by the IV curve. This is a guess. Not sure of the volts or what 3x6 means. If it is 3.6 volts then this is right. Power at Maximum-Watts at STC - 1.8W; Volts at Open Circuit 3.6V?; Volts at Maximum Power 2.8V?; Amperes at Maximum Power .64A?; Amperes at Short Circuit .71?: Your configuration for 72 cells should be 12 parallel groups of 6 cells in series. 6x12. Your final panel at STC would be the following Pmax 129.6W; Voc 21.6V Vmp 16.8V; Isc 8.52A Imp 7.68A. The module will never perform this well. On a good day with a homemade panel you will get 60-70W hopefully. Under load this will put out 11.5 to 15V depending upon type of load and under the correct circumstances. Perfect for charging 12V batteries.

3x6 is the dimension of the cell used 3" x 6"

If you want to increase output current then connect parallal but if you need more voltage (depends on your equipment ratings) then you can connect series.if you connect series more batteries you will not get more currents.focus this connection and then you can design.

So if you want force and voltage, place 2 of 4 panels in series and 2 in parallel