Good adivce is hard to find.

[Guest]

Hello All! im looking at getting the rest of my solar stuff together this week and this is my first time.The all mighty Internet has provided only confusion.Any help would be appreciated.

2x 12v 105ah batteries - already have these....i know 6v are better... i missed the train on that one.

280w 24v single mono panel( really good deal right now). - Is this better/more efficient when using an MPPT controller to step it down to 12v then lets say 12v panels with a PWM controller of similar watts

20Amp MPPT controller. - Should i get a 30amp in case i expand or will a 20amp provide plenty with 24v panels?

i already have a 3000w inverter. I know people will say its to big for 12v batteries but i only use it for light duty( biggest thing would be coffee maker ). - I already have a class T fuse block. What fuse should i run for this thing? 200-400amp? and recommendation on wire size? is Class T fuse the proper fuse?

My last question is with wiring....if i have 2 x 12v batteries. Should i put the inverter wires and the solar wires on different battery terminals or will they be fine sharing the same - + posts?

Please help the internet is a scary place. Since i have not bought some of this stuff im open to suggestions as well. Thanks

[inetdog]

You will get lots of good advice here, although you may not like it.
To start you off, a coffee maker can be a 1000W load, and that means around 100A of DC out of your batteries. If you were to go to the full 3000W for any reason you would be pulling 300A and the wiring for that is not something you want to get involved with 24V would be a lot better.
Also, for parallel battery connections read up on the information at http://smartgauge.co.uk/batt_con.html.

If you can come up with a comprehensive list of what loads you want to power, and for how long in each 24 hour period, we can give you much better advice.

The whole process of sizing a system is covered in multiple sticky threads in the Off Grid topic area.

[Logan5]

Stop thinking inside of a 12volt [BOX]

[Guest]

Thanks for the useless reply. You feel better now? I sorted it all out locally from a solar shop. Its up and running beautifully minus the inverter which i will resize. All done in a 12v[BOX].

[jflorey2]

280w 24v single mono panel( really good deal right now). - Is this better/more efficient when using an MPPT controller to step it down to 12v then lets say 12v panels with a PWM controller of similar watts

MPPT is better.

20Amp MPPT controller. - Should i get a 30amp in case i expand or will a 20amp provide plenty with 24v panels?

Panel voltage doesn't affect current rating. Panel voltage affects voltage rating (input side) of controller. To determine current required, divide panel wattage by battery charge voltage (usually 13-14 volts.)

i already have a 3000w inverter. I know people will say its to big for 12v batteries but i only use it for light duty( biggest thing would be coffee maker ).

Get a different coffee maker and use a smaller inverter.

I already have a class T fuse block. What fuse should i run for this thing? 200-400amp? and recommendation on wire size? is Class T fuse the proper fuse?

Fuse should be ~250 amp for that inverter.
Wire size depends on run length, but in no case should be less than 2ga.

My last question is with wiring....if i have 2 x 12v batteries. Should i put the inverter wires and the solar wires on different battery terminals or will they be fine sharing the same - + posts?

Wire both your charger and inverter to opposite "corners" of the battery. Not exceeding 2 connections per lug is a good rule, so connecting the charger to the inverter (not the battery) would be a good idea. Remember that fuses protect wires, so any wire that attaches to the battery directly is unprotected, and any wire that attaches after the fuse must be able to carry 250 amps momentarily (i.e. you can't just use 18ga wire to go to your charge controller.)

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[Sunking]

That 3000 Watt Fire Starter you have requires 250 amp fuse and a 4/0 copper cable the size of your wrist. Neither your battery or Inverter is made to terminate a 4/0 cable.

It does not matter what your intent is or what you think. Your 105 AH battery can only handle up to a 400 watt Inverter. Your Inverter burns 30 to 40 watts setting there collecting dust, in a day you burn 30 watts x 24 hours = 720 watts hours as waste heat on a battery that only has 2500 watt hour capacity. That means you use 1/3 of your battery capacity each day doing nothing but setting there.No one can fix that or help you.

You may think that is not helping you or useful, we do not care. We cannot help you if everything you have done is wrong and you refuse to correct all your mistakes. Like I said your Intent means nothing. You just bought your 16 year old kid a new Corvette because he promised he would never go faster than 50 mph. In this case you lied to yourself and believe it.

[Sunking]

2x 12v 105ah batteries - already have these....i know 6v are better... i missed the train on that one.

You missed more than the train here. Makes no difference what voltage you configure them for 12 or 24 volts. Fact is the batteries can only support up to 400 watt Inverter.

280w 24v single mono panel( really good deal right now). - Is this better/more efficient when using an MPPT controller to step it down to 12v then lets say 12v panels with a PWM controller of similar watts

MPPT is always better and you have no choice but to use a MPPT Controller. If you used a PWM controler on a 12 volt battery you turn your 280 watt panel into 100 watts. However with a 280 wat panel you need a minimum 25 amp Controller. Good luck find a 25 amp controller. If you use a 20 amp model you turn your 280 watt panel into 240 watts. You need a 30 amp MPPT Controller.

i already have a 3000w inverter. I know people will say its to big for 12v batteries but i only use it for light duty( biggest thing would be coffee maker ). - I already have a class T fuse block. What fuse should i run for this thing? 200-400amp? and recommendation on wire size? is Class T fuse the proper fuse?

No one can help you with this mistake. Toss it in the trash and get a 400 watt Inverter. You woul dneed a 250 to 300 Amp Fuse and 4/0 cable which is the size of your wrist. Nither your battery or Inverter can terminate a 4/0 cable. It would rip the terminals off from the strain and weight.

My last question is with wiring....if i have 2 x 12v batteries. Should i put the inverter wires and the solar wires on different battery terminals or will they be fine sharing the same - + posts?

No comment.

[Guest]

As per my previous post which you obviously failed to read before making a pathetic Corvette analogy, I resized the inverter already, even before i bought the solar up setup.I came here for some basic advice which i did eventually receive in bits and peaces so i could make a purchase decision and not a bunch of condescending remarks. Everyone is ranting about an inverter, It was the least important question i was asking about since i wasn't even going to install until i figured out the proper specs. You solar guys are worse then bunch of old ladies. MOD feel free to delete this account.

[inetdog]

I feel free not to delete the account or the thread, since it is educational.
You do not have to continue to visit the Forum if you feel that way.

[Wy_White_Wolf]

Since you're replacing the inverter buy a 24V inverter and wire your batteries in series.

WWW

[SunEagle]

I feel free not to delete the account or the thread, since it is educational.
You do not have to continue to visit the Forum if you feel that way.

You did warn him up front that he may not like the advice he would get.

Kind of amazing how people keep coming here to get answers to questions that can't be found on the internet only to get pissed off when they find what they are trying to do is dangerous. All for the sake of saving a few dollars.

To the OP. Good deals on solar equipment may not be really good unless all of the hardware match up so you have a safe and balanced system. Without the proper wire size and fusing something cheap can turn into a fire ball and get someone hurt.

A 30Amp MPPT would be a better way to go with that 280watt panel and a 12volt battery. Although 2 x 105Ah batteries wired in parallel is not a good solution but at least you have enough charging amps to keep that system happy.

As you already understand a smaller wattage inverter is the way to go with that battery system and using any large load like a coffee maker (even for short periods) will quickly drain a battery.

[adoublee]

You solar guys are worse then bunch of old ladies. MOD feel free to delete this account.

Only the most vocal ones 44North. Good luck on your project and stay safe on the interwebs.

[Guest]

Money was never a factor suneagle, i just dusted a 400$ 300w inverter for a $600 pure sine model at much lower watts because i quickly realized it was dangerous and upgraded to a 30amp controller. Soon ill do batteries. I always accept constructive criticism, the thing is none of it was constructive at first hence the reason i was annoyed you understand?. What i was looking for was knowledge to help me make a purchasing decision. I found it. Thanks for those who provided!

[Sunking]

You have a 280 watt panel and 2 12-volt 105 AH batteries. That is all you have to work with and dictates everything else. Fortunately you lucked out as 280 watts is a good match for the batteries. But it does DICTATE everything else.

Wire the batteries in series for 24 volts. With 24 volt battery means much smaller wire, fuses, charge controller, and lot more room to grow, safer, and saves big $$$ today and tomorrow.

If you go 12 volt battery will require a 30 amp MPPT Controller. At 24 Volts only requires a 15 Amp Controller and can grow to 400 watts. A 30 Amp Controller at 24 volt battery can grow to 800 watts, and if you stay stuck inside that 12 volt toy box only 400 watts. So choose wisely.

Either 12 or 24 volts, a 400 Watt Inverter is as large as you want to go with your batteries.

If you go 24 volts requires a 20 Amp 12 AWG wire between Battery and Inverter. If you go 12 volts requires a much larger 40-Amp Fuse and 8 AWG wire (mo $$$$).

Look here for wiring questions.

Lastly, grow some skin and balls. This is the best advice you will ever receive.

FWIW if you go 24 volts will double your battery life. Never ever parallel Pb batteries. Mo $$$$ $aved

[Guest]

There you go again. You guys are suckers for punishment. Grow a pair of balls? This forum is unreal. The only response to that I have is thanks for the real advice on the setup and next time you serve your country overseas twice we can then compare ball size. Until then probably best you stick to what you know. Sensitivity was never the issue. It was respect. You ****ing bum.