Invertor question

[Offgrid]

Yes Sir!!! Just want to say thank you for ALL your help! Seriously want to start a thread called Sunking for president! Lol.You should start a paypal account or something lol.(on second thoughts hehe) So I can move on with some system upgrades now which is awesome.Firstly a combined box and then growing the array to 500w before bumping up voltage (can't wait!) I do have one last question though before I replace that 10amp CC of mine though,My 100w panel is rated at 5 amps imp but current flowing to batterys is usually not more than 3 amps,does that mean I still can add another x2 100w 12v 5amp panels or just,at a push,1 more? We did discuss PWM input amps = output amps but just wanted to clarify so I don't burn **** down.

[Mike90250]

Great, on one thread, someone want's to waterboard sunking, and here, they want to pay him. He must be doing something right

[Sunking]

Great, on one thread, someone want's to waterboard sunking, and here, they want to pay him. He must be doing something right

But I like being waterboarded. I am in TX and can use any type of water. TX is burning.

[Sunking]

Offgrid to answer your question depends on controller type. Once you moove above about the 200 to 400 watt panel wattage, you need to switch to MPPT as th eextra expense is justified and offset by the efficiency gained.

For a PWM charger just make sure the panel Imp total is equal too or less than the charger amp rating. Nothing more to it than that other than do not series up panels to raise the voltage.

An example if you have a standard 100 watt panel it produces 18 Vmp @ 5.55 Imp amps. So you connect it to say a discharged battery. The battery pulls the Vmp down to match the battery. A discharged battery with bulk charge current applied will only develop around 12 volts on the battery terminals. So we know input current = output current. So with 5.55 amps @ 12 volts = 67 watts. Your 100 watt panel is now 67 watts. OK now add the second 100 watt panel in series. Current is still 5.55 amps, and the same battery still only receives 67 watts out of 200.

With a MPPT charger things change drastically. Input voltage is not limited like a PWM. Most can handle up to 150 volts regardless of the battery voltage. So we can series wire the panels to take the advantage of higher voltage efficiency. Take those same 2 100 watt panels in series. The input to the controller is 36 volts @ 5.55 amps. The output to the same discharged battery is 12 volts @ 15.83 amps or 190 watts out of 200.

[Offgrid]

Thats pretty damn awesome.I like the outback range but will need to sell a lung to get one.Might go for a local brand who makes mppt http://www.microcare.co.za/products/...t-tracker.html

Coming back to PWM and keeping the Imp rating for the panels on par with the CC....Heres the thing...x2 100w panels do 5.55amps each so thats 11.1amps.My CC can handle 10amps....This means get a new CC before getting the panel obviously I guess.


Oh btw I heard on the news about the Texas fires.Something about everything is very dry and lots of fuel being around...Refering to all the oil wells etc?

[Mike90250]

You will have to monitor the off-brand MPPT controllers, it's very tricky to get it working right, and Morningstar, outback, midnight and Xantrex have it down. Rogue and BlueSky also have good ones too.

[Crumb]

You will have to monitor the off-brand MPPT controllers, it's very tricky to get it working right, and Morningstar, outback, midnight and Xantrex have it down. Rogue and BlueSky also have good ones too.

As an aside, can you fill us in on that? I am looking at them. The Instapark ones are similar to other brands that, at least in the smaller mppt sizes have been called fakes. I have also seen an HQRP one, looks a little less dubious, but I can't be sure of it. Either is probably built better than my pair of Chicago electric!

How do you like your Sunsaver Mppt?
Is it true about needing the optional extra remote probe to get it to work right in the first place?
(And are they ever referred to as "muppets?" )

And why do we even track the power point?
All this tracking and seeking with fancy hardware...
I know what it is - printed right on the label! - 17.5V! Mystery solved!
So, why do we need fancy equipment for that instead of just hard-optimising for one voltage like 17.5?
Couldn't this be solved with dip-switches or a little knob? (For cheaper.)
I have trouble understanding the approach, but the results sound good most of the time for mppt.

[Sunking]

Oh btw I heard on the news about the Texas fires.Something about everything is very dry and lots of fuel being around...Refering to all the oil wells etc?

No not oil wells silly. Texas has had no significant rain since May. Summer temps have been around 110 for 63 days. The fuel is 268820 square miles of dead dry grass and pasture land.

[Sunking]

And why do we even track the power point?

Have you read this STICKY thread?

Oh I forget, I am on your ignore list, you cannot see any of my post or replies!

[Mike90250]

And why do we even track the power point?
All this tracking and seeking with fancy hardware...
I know what it is - printed right on the label! - 17.5V! Mystery solved!

Because it changes and moves around

I've got a 3 tab spreadsheet here
http://www.mike-burgess.org/images/MB_May-3-2007.htm and the first tab (lower left) has the raw data from the array, and you can see the volts and amps vary over the course of the day.

With one panel, you could "set and forget" but with many panels, the error will build and be a large loss.

[Crumb]

Because it changes and moves around

I've got a 3 tab spreadsheet here
http://www.mike-burgess.org/images/MB_May-3-2007.htm and the first tab (lower left) has the raw data from the array, and you can see the volts and amps vary over the course of the day.

With one panel, you could "set and forget" but with many panels, the error will build and be a large loss.

I do have one panel!
I'll start here:

http://en.wikipedia.org/wiki/Buck_converter#Impedance_Matching

Thanks a million!

[Offgrid]

You get cheaper MPPTs like the Stecca but they dont have the LCD screens which is half the fun to me.Like watching paint dry but addictive!

[Sunking]

You get cheaper MPPTs like the Stecca but they dont have the LCD screens which is half the fun to me.Like watching paint dry but addictive!

You need to use non toxic paint, those fumes are rotting your brain.

[Crumb]

You get cheaper MPPTs like the Stecca but they dont have the LCD screens which is half the fun to me.Like watching paint dry but addictive!

Stecca indicates positive ground/common (I am trying to get away from that.)

http://www.stecasolar.com/index.php?4a3b3d623a641

and I see higher prices than the morningstar with the thermomitor and shipping. Maybe this price difference is due to different countries and so forth.

I would prefer only a low voltage(pulsed)/overcharge(steady) light and a button to activate an LED to confirm charging.
Displays/lights are too hungry in a small/silly system like the one I am building. 0.050 amps for an LED is 1.2 amp hours in 24 hours - or so. (If my math is right.) This is about half my daily discharge capacity at the batteries if I want to keep them charged. Regardless of what I get I have to consider putting the charge light on a momentary-on switch. I have little margin to play with.

For what it is electrically (An mppt controller), the price is surprisingly high - I am surprised the market supports it. The companies making them must be getting nice margins on them. Perhaps I am in the wrong buisness? Hah!

[Offgrid]

Lol,don't make me throw a zippo on your lawn!