Solar Reg. 20 or 30 Amp?

[MarkJ]

Hi Folks

OK now I have sold Nicolle and bought 2 solar panels

YIPPEEE!!!!!!!!

Both are 120 watt Monocrystaline.
Neither are mounted yet, but I have one lashed on deck to get some sun.

They will be mounted properly when a) I work out how to, or b) when I get to a cheaper country.

My question is: I don't have an ammeter on the boat. and can't determine what the panels are putting into the batteries.


There is a regulator with LCD amp indicator thats 20Amps for $169 or a 30Amp one for 199

2x 120=20 amps in theory but I will never get that.

Should I save the $30 and drink more beer? Or should I buy the 30Amp one like the shop recommends?

20 amp: http://www.jaycar.com.au/productView.asp?ID=MP3129&keywords=mp%2D3129&form= KEYWORD

30 Amp http://www.jaycar.com.au/productView.asp?ID=MP3722&CATID=7&form=CAT&SUBCATI D=912

Mark
(The bloke who bought Nicolle is trying to get his money back )

[mesquaukee]

Always go just a little bigger. Especially in the tropics where the ambient air temperature is higher. The charge controller can put out a lot of heat so you want to mount it where there is air movement.

You might want to check out this website http://store.solar-electric.com/tracc35solch.html
A 35 amp Xantrex controller is US$119

[MarkJ]

Originally Posted by mesquaukee

Always go just a little bigger. ...You might want to check out A 35 amp Xantrex controller is US$119

Thanks for that

That Xantrex one doesnt have the LCD screen with the amps readout (extra $100) ... which is kinda all I want, actually.

Mark

[Ex-Calif]

Originally Posted by MarkJ

Hi Folks

OK now I have sold Nicolle and bought 2 solar panels


(The bloke who bought Nicolle is trying to get his money back )

Seeing as how the money is already spent, I am thinking he is outta luck.

You might offer to take her off his hands for a small fee

With the extra $30 or so you get taking Nicolle off his hands spring for the the 30 amp

[camaraderie]

If your goal is to get the most out of your panels rather than simply dissipate the extra full sunlight power as heat...suggest you look into an MPPT controller. Payback on the price differential will be VERY quick with a 15-20% gain over conventional regulators.
Blue Sky SB2512i Charge Controller 25 A 12V MPPT or
Blue Sky SB2000E MPPT charge controller

[chala]

You could also buy a QP5412 6-50A shunt for $12.95 and use it with your multimeter, Nicolle by now should be a champion in electronic, but with 120W of solar, a regulator will be wiser.

[witzgall]

I would buy a MPPT controller that allows you to wire as a 24v array. You can either use smaller wires from the panels to the controller, or lose less voltage over the length with the same wire. I got a great deal on 8AWG from Defender, $16.99 for 25 feet.

I think also that by wiring as a 24v array, you will get more amps into the batteries, in certain situations. One is partial shading, where the voltage might drop down below 24v, but still above 14v, so charging can still occur.

I just installed two 24v panels, 120watt, this past weekend. I wired them in parallel, 24v, and used a BZ MPPT500 controller. I have read both good and bad things about the controller, so we will see. The price was right. By the time time I had everything hooked up, it was heavily overcast, I was still getting between 1-3.5 amps into the batteries.

Chris

[MarkJ]

Originally Posted by chala

QP5412 6-50A shunt for $12.95 and use it with your multimeter, .

Yes, I was thinking of that with the $17 Ammeter. But the 6-50A... but I want to be able to read under the 6 amps. Do they show up at all?

I tell ya what, this solar pannel is picking up the sun! Can't wait to get the second and can't wait till I can properly see how many amps its doing.

[mesquaukee]

Build your own Shunt

You could make your own “shunt” that is accurate to 0.1 amps.
You could measure the voltage drop across a fixed length of wire.
12 gauge wire, 76 inches long has a voltage drop across it of 10 mV per 1 amp of current, or 6 amps would read 60 mV on the multimeter.
If using 14 gauge wire, 47” long, and for 16 gauge wire, 30” long. Have Fun.

[forsailbyowner]

I just run an ammeter, diodes and fuse. Have 300 watts plus. With a large battery bank even the 15-20 amps is just a trickle.

[Cowboy Sailer]

Mark, I was surprised to see the output of solar cells go up by about 20 per cent from cloud edge lensing effect. You need to prepare for more than 20 amps. It sounds strange to think that the output of a solar array could go up on a day with scattered clouds but it can.

[MarkJ]

Originally Posted by Cowboy Sailer

output of solar cells go up by about 20 per cent from cloud edge lensing effect. .

Goodness! A bit of that and the beer will be really cold!

[CSY Man]

I would go with a "booster" instead of a regulator as the MPPT in itself is a very efficient regulator: I have had the Blue Sky 2000E for a couple of years and love it..
Saw an immediate difference of about 10% +

[bill good]

G'day Mark KISS So long as you have at least a panel voltmeter the rest is 'nice to have'. MPPT seems to be the no 1 choice. BZ MPPT products get a lot of bad reports. In the price range you are looking at you might look at the PS15 PWM unit. I am still rewiring my electrickies to include 80v 400watt solar system!! Just have to mount the panels all the internal wiring done.

regards bill

[MarkJ]

Originally Posted by CSY Man

: I have had the Blue Sky 2000E for a couple of years and love it..
Saw an immediate difference of about 10% +

Originally Posted by bill good

KISS So long as you have at least a panel voltmeter the rest is 'nice to have'.
regards bill

Look, as the town I am in only has the Jaycar regulator - MPPT - I might just wait for a few months till I can see them all at once.

An ammeter in the solar panel line will tell me how much its putting in; the Multimeter stuffed into the cigarette lighter tells me if the battrey needs a charge when the sun goes down and if the fridge don't start I know there is no battery left or too much turned on.

With a system like that I can't fail


Mark