80 Watt Solar Setup

Gang,

I am now the very proud owner of a 80w folding panel....I went and picked up the unit today raced home to set it up in the back yard for testing before our trip in Feb. This is what I have found so far:

Volts at the alligator clips were 10v (it was a little cloudy)
105amp Deep Cycle battery fully charged overnight showing 12.8v
40L Engel connected to the battery

I would have thought the volts should show higher around the 13volts at the clips? I have not checked the volts before it goes into the controller will do that when I get home. The regulator shows battery full and there is a load on the battery. I am not going to go into where I got it from but here are the specs per 40watt panel
TYPE
40 Watts
Solar cell
Mono
Maximum power (Wp)
40.00
Maximum power voltage (V)
18.00
Maximum power current (A)
2.23
Open circuit voltage (V)
21.60
Short circuit current (A)
2.44
Cell Efficiency (%)
16.50%
Number of cells (Pcs)
36(4*9)
Size of module (mm)
610*534*35
Maximum system voltage (V)
1000V
Temperature coefficients of Isc (%)
0.03%/?
Temperature coefficients of Voc (%)
-2.2mV/?
Temperature coefficients of Pm (%)
-0.55%/?
Temperature coefficients of Im (%)
0.03%/?
Temperature coefficients of Vm (%)
-2.2mV/?
TemperatureRange
'-40C------+85C
Surface Maximum Load Capacity
60m/s(200kg/sq.m)
Allowable Hail Load
steel ball fall down from 1m
Weight per piece (kg)
4.50
Output tolerance (%)
±3%
Frame (Material, Corners, etc.)
Aluminum
Standard Test Conditions
1000W/m2 AM1.5 25’C
FF (%)
=74%

So I guess my question is what volts should I expect at the alligator clips?

Can anyone recommend a good amp clamp meter? I have been looking at the one at Jaycar for $120 but there must be cheaper ones out there?
Back Expand Un-Read 0 Moderator

Reply By: outsider - Thursday, Jan 21, 2010 at 14:36

Thursday, Jan 21, 2010 at 14:36
Being a folding panel I would imagine that the controller is on the panel and you have several meters of wire to the battery.

I found I was getting a considerable voltage drop over the wire and removed my controller from the panel and located it at the battery end of the wires.
This pretty well doubled the amps i was getting out of the panel as the controller was getting a more accurate voltage reading from the battery.
AnswerID: 400454

Follow Up By: Member - Troll 81 (QLD) - Thursday, Jan 21, 2010 at 14:51

Thursday, Jan 21, 2010 at 14:51
You are correct it's got a 10m lead
0
FollowupID: 669614

Follow Up By: Member - Troll 81 (QLD) - Friday, Jan 22, 2010 at 09:55

Friday, Jan 22, 2010 at 09:55
Outsider,

I did some more testing last night and I replaced the dodgy clips that came with it with some good quality ones and re soldered the wires etc etc. I then took a volt measurement at the battery and it was 12.4 and I also put it at the other end at the panel and it showed 12.3...so 0.1 drop is probably not to bad over 10 meters?

Let me see if if I have this right
If I was to move the controller does that mean I will have to run 2 sets of wires still?
join the 2 panels together and run one long cable to the controller and then a thicker much shorter to the battery?
0
FollowupID: 669731

Follow Up By: outsider - Friday, Jan 22, 2010 at 10:35

Friday, Jan 22, 2010 at 10:35
"join the 2 panels together and run one long cable to the controller and then a thicker much shorter to the battery"

That sounds right to me.

I would be surprised if you were only getting a voltage drop of 0.1v over 10 meters

0
FollowupID: 669741

Follow Up By: Maîneÿ . . .- Monday, Jan 25, 2010 at 10:48

Monday, Jan 25, 2010 at 10:48
Troll,

Are you saying you have two (2) POS (+) & two (2) NEG (-) cables going to the battery ??

"If I was to move the controller does that mean I will have to run *2 sets* of wires still"
"join the 2 panels together and run one long cable to the controller and then a thicker much shorter to the battery"

Wire the two panels together, then run just one *set* of cables to the solar regulator situated at the battery, with same cable size all the way.

Maîneÿ . . .


0
FollowupID: 670194

Reply By: signman - Thursday, Jan 21, 2010 at 14:47

Thursday, Jan 21, 2010 at 14:47
Agree with outsider...
Remove the reg. off the panel unit and position as close to the battery as possible.

AnswerID: 400459

Reply By: Ozhumvee - Thursday, Jan 21, 2010 at 15:09

Thursday, Jan 21, 2010 at 15:09
Another way to boost the output is that with the frig and the panel connected to the battery at the same time you can remove the regulator completely especially as you have to manually connect the panel when you want it to charge the battery and are disconnecting it at night and when travelling.
With a constant load (frig) the panel will never overcharge the battery.
Peter
1996 Oka Motorhome

Member
My Profile  My Position  Send Message

AnswerID: 400461

Follow Up By: Maîneÿ . . .- Monday, Jan 25, 2010 at 10:52

Monday, Jan 25, 2010 at 10:52
when the fridge is not running, what's happening to the battery ????

Maîneÿ . . .
0
FollowupID: 670196

Reply By: bruce - Thursday, Jan 21, 2010 at 16:00

Thursday, Jan 21, 2010 at 16:00
I have been watching those panels with some interest...can you check the out put when the panel is partially shaded and I mean very, very little shade on it....does it drop off ?(I assume that it will)..or does it stop completely ?...why I am asking this is because I had a "Suntech" brand 85w a couple of yrs ago and with any shadow on it and I mean ANY shadow on it and it was dead...I now have Uni-Solar 64w that does still work when partially shaded and am considering one of these folding type to supplement it...you are the first person that I have seen that has commented on them...cheers
AnswerID: 400468

Follow Up By: Member - Troll 81 (QLD) - Thursday, Jan 21, 2010 at 16:04

Thursday, Jan 21, 2010 at 16:04
Will let you know...I am going to buy a clamp meter soon so will have more accurate figures. By the time I get home it will be around 4pm and I am guessing the sun won't be at it's optimum but will record the numbers and let you know
0
FollowupID: 669624

Reply By: Member - Ed C (QLD) - Thursday, Jan 21, 2010 at 16:56

Thursday, Jan 21, 2010 at 16:56
re the clamp meter, may I suggest you have a look at ebay, type "Uni-T clamp meter" into the search field, and take your pick from what comes up ;-)

There's a handful of Hong Kong based sellers offering these at (more or less) similar prices..

A couple of years ago, Mike Harding picked up one of these (UT 203 from memory?), tested it and reported his findings here on the forum, whereupon he gave it the thumbs-up for accuracy of readings, and in particular, value for money...

I believe Mike knows 'a thing or two' about electrickery (and IMO the forum is the poorer for his choosing to no longer participate), and his endorsement was good enough for me to buy one...
For a few $$ more, I picked up the UT 204, and I've been more than happy with it (though I have no way to verify the accuracy of the readings, I take 'em at face value;-)) .. (YMMV)

:)


Confucius say.....
"He who lie underneath automobile with tool in hand,
....Not necessarily mechanic!!"

Member
My Profile  Send Message

AnswerID: 400472

Follow Up By:- Thursday, Jan 21, 2010 at 19:30

Thursday, Jan 21, 2010 at 19:30
Ed C,

you can verify their (un)accuracy, by wiring a cheapish multimeter into the circuit for testing purposes. Read on if this if of interest to you...

A few general comments first:
Clamp meters can introduce large errors at low currents.

E.g. if the accuracy of a 4000 count unit is specified +/-1% of reading + 1 LSD for DCV, then the same meter could have a much worse accuracy of e.g. +/-2.5% of reading + 3 LSD for DCA.
In other words, measuring say 20VDC, your meter could show anything between 19.79V and 20.21V which would be sufficiently accurate for most jobs.

But if you'd measure a 40W solar panel's output current of around 2.5A, the meter could show anything between 1.44A and 3.56A, or +/- 42.4% of the expected value which is a large and significant deviation from the real thing.

Using conventional multimeters on their DCA setting gives a more accurate picture, but care has to be taken to keep probe wire/clamp resistance as low as possible in order to prevent excessive voltage drop (which would reduce the battery charging current quite a bit).

Whenever I do current testing on battery charging circuits, I like to wiggle the banana style plugs inside their receptacles several times. This scratches off any contact surface oxidisation, resulting in a much more accurate reading.

Best regards, batterymeister

0
FollowupID: 669651

Follow Up By:- Thursday, Jan 21, 2010 at 21:07

Thursday, Jan 21, 2010 at 21:07
oops, error on my side:

the current measurement would be out by up to +/- 92.5mA, so you could expect a reading of between 2.41A and 2.59A which is quite an acceptable range of uncertainty.

My apologies.

Best, batterymeister
0
FollowupID: 669671

Follow Up By: Member - Troll 81 (QLD) - Friday, Jan 22, 2010 at 09:47

Friday, Jan 22, 2010 at 09:47
I ended up stopping at Dick Smiths on the way home and picked up a good one I think. I have been looking at the ones on eBay for a while but I think those $20 ones wont be very good and the accuracy will be poor.
0
FollowupID: 669730

Follow Up By:- Friday, Jan 22, 2010 at 10:04

Friday, Jan 22, 2010 at 10:04
It's always advisable to compare specs and accuracy figures.

If I'd be in the market for a DC current clamp meter with reasonable accuracy, I'd go for the directly imported ones on ebay.
The importer has a full specs sheet there, together with detailed and meaningful accuracy figures - something I don't get to see at jaycars more expensive offerings.
No data no deal :(

Best regards, batterymeister
0
FollowupID: 669732

Reply By: Mandrake's Solar Power- Thursday, Jan 21, 2010 at 21:43

Thursday, Jan 21, 2010 at 21:43
I will run some tests on mine tomorrow night and post the results here at about 7 pm if anyone is still interested -
I'll do a full sun both panels .
full sun with 1 panel covered
full sun with bottom half of both panels covered ..

Does that cover most situations do you think ?

Measure volts at reg and alligator clip - Should do ..

Cheers

Mandrake
AnswerID: 400521

Follow Up By: outsider - Friday, Jan 22, 2010 at 01:32

Friday, Jan 22, 2010 at 01:32
I would be interested in the panel angle,
I had read that here in brisbane around 26 degrees facing north would be the best angle but after testing I have found that this time of year laying the panel flat produced the most amps.

Quite often see folks with their panels up around 60 degrees, doubt they would be very efficient at the angle.
0
FollowupID: 669706

Follow Up By: Mandrake's Solar Power- Friday, Jan 22, 2010 at 07:13

Friday, Jan 22, 2010 at 07:13
My main panel is flat on the roof of the jeep !! So I lose the first and last hours of sunshine - From memory I think the angle has something to do with your latitude ? Rule of thumb ?
But that angle would need to be changed during the year to be aligned with the sun .. Might try a couple of different angles as well tonight ..

Cheers

Steve
0
FollowupID: 669718

Follow Up By: bruce - Friday, Jan 22, 2010 at 10:20

Friday, Jan 22, 2010 at 10:20
If the shade at the rear of the panel was the same or similar dimension as the panel then the angle to the sun would be right....correct ?
0
FollowupID: 669733

Follow Up By: Mandrake's Solar Power- Friday, Jan 22, 2010 at 10:30

Friday, Jan 22, 2010 at 10:30
At midday (sun time ) Yes ...

What you need is a rod mounted at right angles to the panel and keep its shadow to a minimum - then the panel will be pointed at the sun correctly ..

Cheers

Mandrake
0
FollowupID: 669737

Follow Up By: signman - Friday, Jan 22, 2010 at 10:39

Friday, Jan 22, 2010 at 10:39
Ideal positioning is facing 'solar' north (as opposed to magnetic north)
With the angle set at your location latitude.
BUT- this only applies at equinox.
So on the equator- the panels would be set horizontal- and at the poles they would be vetrical.
Equinox is aslo the only time a sun-dial is accurate. not allowing for the +/- calculations required !!

0
FollowupID: 669742

Follow Up By: signman - Friday, Jan 22, 2010 at 12:38

Friday, Jan 22, 2010 at 12:38
Another way to obtain the optimum angle:
Stick a stick in the ground.
Measure the length of the stick and divide this by the length of the shadow cast.
This would give you the tangent of the required angle when subtracted from 90 dgrees.
Also, the direction of the cast shadow would indicate solar north at that moment.

eg. At my location (just SW Sydney) at 12.24pm AESST- a 300mm stick cast a shadow of 90mm.
The tangent resulted in an angle of 73.3 degrees. Subtracted from 90 would yield an optimum angle of 16.7 degrees.
This would be correct as the Summer Solstice was only a month ago.

0
FollowupID: 669762

Follow Up By: Mandrake's Solar Power- Friday, Jan 22, 2010 at 16:08

Friday, Jan 22, 2010 at 16:08
Due to severe overcast conditions testing is postponed for a day or so ...

"It may not happen overnight but it will happen."

LOL

Mandrake
0
FollowupID: 669801

Follow Up By: Mandrake's Solar Power- Sunday, Jan 24, 2010 at 12:39

Sunday, Jan 24, 2010 at 12:39
OK - Clouds went away and I got the Kit out and set up for tests ..
2 X 50 watt Solar Kit at 20 degrees to the vertical facing the sun .
Manufacturers data as supplied
Short circuit Amps 2.96 X 2 = 5.92 Amps
Short Circuit Voltage - 21.6 V
Rated at 2.77Amps at 18 Volts X 2 = 5.54 Amps
Ambient Temp was 22 C approx. ..
Time of test 10.30 am to 10.50 am .
2 different Multimeters which were changed to verify results ..
Amp measurements were taken between the +ve ali clip and +ve battery terminal.

This was not as easy as I assumed - My Multimeters were dancing all over the place
and was very ( impossible really ) to get any accuracy however the results are
interesting if not totally accurate ..

The constant load used was an old 12v auto fan-heater - running fan only.

BOTH PANELS .

Volts measured at controller input - between 19.7 and 20.3 .
Volts measures at controller output - 14.7 ( under constant load )
volts measured at Ali clip - 14.0 ( Under constant load )
Short-circuit Amps was 6.09
I tried to measure Amps but the range on the
display was flicking from 0.8 to 6.18 !!!

SINGLE PANEL ( 1 Panel totally covered )

Volts measured at controller input - between 19.7 and 20.3 .
Volts measures at controller output - 14.7 ( under constant load )
volts measured at Ali clip - 14.0 ( Under constant load )

Short-circuit Amps was 3.05

BOTH PANELS ( lower half of both panels covered )

Volts measured at controller input - between 19.7 and 20.3 .
Volts measures at controller output - 14.7 ( under constant load )
volts measured at Ali clip - 14.0 ( Under constant load )

Short-circuit Amps was 0.13 !!

So as long as one complete panel is in full sun the kit works well
Any amount of shade over both panels reduces output dramatically .

The cable supplied with the kit is 5 metres long and "obviously " not
large enough as the voltage drop was 0.7 volts !! Moving the controller
closer to the battery would solve that issue as would changing to a
larger diameter cable .

Cheers

Steve
0
FollowupID: 670084

Sponsored Links

Popular Products (14)