480 Watts = ?

[milezone]

Hi Guys,

Ok not too good on the math part of this, so this goes to the pros.

I am in SW kentucky, and I have (4) 120 watt solar panels hooked together at 12 volts, going through a 20 amp controller and then to (4) 105 amp batteries.

My question is what does this equal to in daily wattage?

Thanks

Milezone

[russ]

From PV Watts -

Jan 42 kWh
Feb 45 kWh
Mar 58 kWh
April 56 kWh
May 58 kWh
June 58 kWh
July 60 kWh
Aug 57 kWh
Sept 52 kWh
Oct 53 kWh
Nov 39 kWh
Dec 36 kWh
"Year" 493 kWh

PV Watts is calculated from long term data meaning the 'average' year - some will be better and some not as good.

PV Watts starts with 1 kW so I enter 4.8 kW and take 10% for a result.

Russ

[Sunking]

My question is what does this equal to in daily wattage?

You mean watt hours but to answer your question 0 watt hours because you burned up your 20 amp charge controller trying to push 40 amps through it.

[milezone]

Hmmmm well the controller is ok, but you are correct my 20amp breaker blew. Luckily I have that. Ok well sounds like my panels are more than 20 amps? I could have swore they were only like 5 amps per panel.

While I am on the subject of blowing things Am I ok with the 4 batteries? I checked the panels and was getting 18.5 volts as of 6:00pm today, if that helps any?

Milezone

[milezone]

Hi Guys,

Also I was always thinking of switching to a MPPT controller, and I know in the next few months I am going to add another 240 watts of solar (making it 720 watts total), can anyone recommend a good controller for this setup?

Milezone

[Sunking]

Hmmmm well the controller is ok, but you are correct my 20amp breaker blew. Luckily I have that. Ok well sounds like my panels are more than 20 amps? I could have swore they were only like 5 amps per panel.

Milezone currents and voltages all depend on panel specifications, how the panels are configured, and charge controller type.

All you stated is you have 4 120 watt panels and a 20 amp charge controller.

I assume you have standard 12 volt panels, wired in parallel. So if that assumption is correct your panel specs are likely 18 Vmp and 6.67 amps Imp. So if you have 4 of them in parallel will yield a Imp current of 4 x 6.67 amps = about 27 amps input to the controller @ 18 volts.

As for controller type can be either PWM or MPPT.

With PWM the Input Current = Output current. You are trying to pump in 27 amps into a 20 amp device. That will eventually let the magic smoke out. Sounds like you already know you have trouble because your breaker is too small. The breaker needs to be a minimum of 30 amps. So if you have a 20 amp PWM controller and the panels wired in parallel you are heading for trouble.

I doubt you have MPPT so no need to go into that, but if you do, then you have turned your 480 watt panels into 260 watts because that is all a 20 amp MPPT charge controller will pass to the batteries (20 amp x 13 volt).

Either way you are screwed.

[milezone]

I thought MPPT Controllers were better? If I get a 60 amp Outback, would that not be a good one to get the most out of my setup?

Or should I just go get a 60 amp PWM, as you make it seem like that will get my 480 watts to work together?

And yes I have them parallel to keep a 12 volts setup. So yes I do need a new controller, would love to hear what you recommend for me. I have a few bucks to burn.

Milezone

[Sunking]

I thought MPPT Controllers were better? If I get a 60 amp Outback, would that not be a good one to get the most out of my setup?

MPPT controllers are a lot better, much better. Problem is with your setup if it is MPPT and 20 amps it will limit the battery charge current to 20 amps. Watts = volts x amps. So with a 20 amp MPPT controller operating in 12 volts the max wattage you can input without wasting panel wattage is roughly 13 volts x 20 amps = 260 watts. Anything over 260 watts will not be used.

Before I go into a detailed explanation read this thread please. After you do you will understand this:

If you used say a 30 amp PWM controller vs a 40 Amp MPPT controller with your panels at 480 watts:

The PWM controller will output 13 volts x 26.7 amps = 346 watts out of 480 input.

With a 40 amp MPPT controller will output 13 volts x 35.3 amps = 459 watts out of 480 watts input.

[Mike90250]

Rouge has a new mid (60v) voltage MPPT charge controller out,

http://www.roguepowertech.com

30A 12 / 24 v battery

[milezone]

Hi Sunking,

First thank you for the help, I know we noob's can be a pain in the rump.
Ok so I am going with a 60 amp outback controller. This should give me plenty as you say for my 480 watts, and room to add 2 more. Is this the proper thinking?
Which means I need to bump up my fuse also to 60 amp, correct? Thanks

Milezone

[milezone]

Went with Northern Arizona Wind & Solar. Great help they were as well. Got a new 60 amp Outback controller, MNEDC-Quad Enclosure for 1-4 Panel Mount Breakers, 3 60 amp breakers, some wires, and ground bus bar (to ground the entire system). Watch out, I am working for the total NEC Spec legal and approved system.

Milezone

[Sunking]

Ok so I am going with a 60 amp outback controller. This should give me plenty as you say for my 480 watts, and room to add 2 more. Is this the proper thinking?
Which means I need to bump up my fuse also to 60 amp, correct? Thanks

Milezone

Ok now you are talking and have something to work with. First you do not have to be stuck with wiring your panels in parallel anymore. Which is great because it is parallel is very inefficient. You can now use a series/parallel combination. With 4 panels you can wire them all in series to get the voltage up and current way down.

Operation with 12 volt battery your panel wattage is limited to around 800 watts input. If you move up to 24 volts you can input 1600 watts, and at 48 volts 3200 watts.

As for the combiner fuse now depends on panel configuration. If you stick with 4 panels in parallel you will need a 30 amp fuse/breaker. Wire them in series and you only need a 10 amp breaker.

[milezone]

The only problem I have is my inverter, it is 1,000 watt pure sine wave, but 12 volts. So if I do change to 24 volts, I would have to get a new inverter, whcih are quite expensive.

[Sunking]

The only problem I have is my inverter, it is 1,000 watt pure sine wave, but 12 volts. So if I do change to 24 volts, I would have to get a new inverter, whcih are quite expensive.

Yes you will, that is life. You feel into the trap of 12 volts which is very limited and inefficient.

[Securityxpert4u]

The only problem I have is my inverter, it is 1,000 watt pure sine wave, but 12 volts. So if I do change to 24 volts, I would have to get a new inverter, whcih are quite expensive.

Don't know how much you paid for your inverter, but you can always use a step up or step down DC converter to use it with the ideal 24V or 48V series string...just a thought