Hi,
I'm trying to design\calculate my solar system components so I'm trying to figure out each technical details of the devices.
OK, let's see if we can help untangle this mess...
1. Max. Solar Input Power, 12V system (720W, 20V-80V DC) - why I care about the input VDC? the solar panel generate watt so I just need to be sure that the maximum solar watt isn't go over 720w, how the VDC range relevant? most of the solar panel doesn't contains output VDC which relevant to the charge controller voltage input?
The VDC or MaxPVInput rating is the maximum voltage the controller can take in before it fries. On the panel's data plate will be a number for VoC which is Voltage Open Circuit, or the voltage the panel can put out under STC standard testing and no load. It's like taking an American 120v light bulb and plugging it into your 220v socket. The voltage is too high and the light bulb goes POP! You use the VoC number for calculating how many panels you can put in series together as in series you add the voltage up but the amperage stays the same.
As a napkin math example, let's say you bought some Generikk Brand 100w panels. On the back you've got a VoC of 22v, a Vmp of 20v, and an Isc of 5a. You buy a controller that says MaxPVInput 100v on the sticker. Well, you look at the numbers and you see that with a Vmp of 20v, you could string 5 together and get every drop of power out of your panels, then your SCC smells like magic smoke.
The VoC is what the panel is trying to put out under load, so when you strung those panels together it actually sent 110v into the controller and the controller couldn't handle it. Solar panels also get better as they get colder so when it's cold the VoC actually goes UP. The rule of thumb is that unless you live in Antarctica, Scandahovia, or our wives' feet, panels will never get cold enough to have to calculate so leave yourself ~20% headroom or so. So in the example above, go for 4 panels in series for 88v and even on a really cold day you'll still be lower than your controller's limit.
2. what is difference between Max. Solar Input Power Max. Solar Input voltage, for example:
Max. Solar Input Power: 12V system (720W, 20V-80V DC)
Max Solar Input Voltage: 160V DC (25°C), 155V DC (-25°C)
it seems that the max solar input power is 80VDC but in specific temperature its 160 max?
Max Input Voltage is how many panels in series you can string together. Some controllers have different limits for different voltages, PowMr being one of the most common. If you're running a 12v based system it can use anything between 20 and 80v, and if you're running a 24v based system it can use anything up to 160v. It's black voodoo magic. If you're running a 12v system and try to throw a 150v string at it you'll have magic orange smoke.
Max Solar Input and Max Power input are the maximum watts the controller can USE to charge your batteries, the effective capacity of your controller. Let's go back to the example system above with the Generikk brand 100w panels. Your controller says it can take a maximum of 720w, but only 80v. OK, so the 80v is a HARD limit so with a 22v VoC you're stuck with a maximum of 3 panels in a string which brings you to 300w of panels (20v Vmp * 5amps = 300w). Well, you could hook up multiple strings in parallel because in parallel you add the AMPS but the VOLTS stay the same, so you decide to get 9 panels and make 3 strings, we call that a 3s(eries)3p(arallel) arrangement. Your total volts are 66v (because 3 panels in SERIES) and you're bringing in 15a (because 3 strings in PARALLEL) which SHOULD give you 900w!
Oh krap, but the controller says max of 720! Did I break something?
Nope, relax. So solar panels are rated by test lab conditions and unless you live in that test lab you're not going to get 100w out of a 100w panels. If you can get 80% on a regular basis you're doing pretty good. If you live in Seattle and can get 10% you're doing pretty good too. ?
So what will happen is that in the earlier part of the day when the sun really isn't doing much, your voltages will get up to where it can start charging the battery a little, which is better than none. When the sky isn't perfectly clear you'll still get charging out of so many panels because each panel in the string only has to work 1/3 as hard to start charging the batteries. Only in perfect sun with no clouds at 25c aimed directly at the sun will you really ever see 100w out of each panel. This is called "Over Paneling" and is actually good practice.
But what about the 750w limit?!?! Well, so the sun comes out one day, it's aimed perfectly, and you've wheeled all your panels into the lab and they're really cranking. Since panels don't PUSH power into a system, the controller ASKS the panels for power and the panels GIVE what they can. The controller can ASK for 720w and if the panels can do it they'll GIVE the 720w, but if the panels have 900w available, the controller is still asking for 720w so it's all good. Much like breaking a 5ver for a candy bar, the clerk only WANTS 1.50 but you HAVE 5 and can GIVE 1.50 to the clerk.
Does that make sense?
3. In inverter, the parameter of 110\220vac is mention and also the 3000W. what each one means? the total W doesn't contains the vac?
That's odd to see a 110/220 on an inverter as inverters take 1 voltage of DC and convert it to 1 voltage of AC, so 12v-110v or 24v-110v or 48v-220v, or 12v-220v or whatever it may be. I've never heard of an inverter that can take multiple DC voltages OR that puts out multiple AC voltages, you just get the inverter for your needs.
The 3000w limit is how much power the unit can push out before magic orange smoke becomes a thing. It's the same whether you're doing 220v @ 13,6a or 12v @ 250a since watts are watts either way.
If you have a 3000w inverter going from 12v DC to 220v AC it will need 250a available on the DC side and can put out 13.6a on the output side. 12v * 250a = 3000w, 220v * 13.6a = 3000w.
If you had a 3000w inverter going from 48v DC to 220a AC you'd need to have 62.5a available on the DC side. 48v * 62.5a = 3000w
There is no such thing as an inverter that can take multiple voltages and put out multiple voltages, so you gotta choose the right one for your system.
In addition, some link of tutorial\DIY guide to understand how to measure the component values will be great.
thanks
Grab a copy of Will's book and go peruse his earlier works on
his YouTube channel. He goes over how the basics of electricity work, what the components do, how to size a system, beginner mistakes, etc. Make up a pot of tea and get cozy, there's a LOT of good information there.
Hopefully this has helped make sense of things a bit.
