What size of solar system

[Sunking]

Thanks Sunking for setting me straight

You are Welcome. By the way I don't care what John, Dave, and Chris say about me on other forums. They know who they are and yes I see their comments. I don't care.

I am one of them Train Drivers. Great company Boeing is. They also have a Solar Panel Division if you like paying $100/watt for a panel.

Good luck to you.

EDIT NOTE:

This might help explain some things about 12 volt systems. Back in the early days of solar of 20, 30, and even to some extent 10 years ago, there were no Grid Tied Panels, PWM or MPPT charge controllers, readily available 24/48 volt inverters, or a lot of deep cycle batteries on the market. All there was to choose from is 12 volt inverters for mobile users like RV's and Truckers, and golf cart batteries were the only game in town. None of that is true today, except the mind set of being trapped in a 12 volt box. Back in those days it was only utilities that used 24, 48, 96, and 144 volt systems. My guess is the person who set it up is old and set in their ways and not up to date trapped in his 12 volt box.

Don't feel alone, 90% of the folks that come here are trapped in a 12 volt box. Still has applications in RV's, Boats, Truckers, and toys but has no place in a home off-grid system of any usable practical size.

[Sunking]

I will tell you that the guy who put this together knew what he was doing and spared no expense in the wiring for this system when he put it together.

You are the only one who believes that and not fooling anyone but yourself. Anyone who bought 12 6-volt batteries, made 6 parallel 12 volt battery strings has no clue what they were doing or how dangerous it is. That is why you caught so much flack. You had no clue. Neither did the person who put it together. I can tell you that persons Mind Set. He is trapped in a 12 volt box and has no clue he could have bought the right size batteries and used higher voltage. All he knew was golf cart batteries and 12 volt systems.

That is not busting your chops, just the facts. The only truthful statement is: "Spared No Expense", To bad he could have done it right for a lot less money if he knew what he was doing. Otherwise you would not have to fix it. So be honest with yourself. We did not make you mad. You did that all by yourself from lack of knowledge. We just had to give you an attitude adjustment upside the head with a 2x4 to get your attention.

[russ]

Thanks again for all your input, cockiness or not.

Jaust comes asking for help and likes to spout off.

[Jaust]

Thanks guys, that's the first time anyone had explained what problems this may cause. I will tell you that the guy who put this together knew what he was doing and spared no expense in the wiring for this system when he put it together. When I'm up there next week I'll get all the specs and info with pictures of the setup. I've been looking all over the internet and watched so many videos of different setups and how they're micky moused together and I don't know exactly what size wiring I have but I know it's more than adequate. I'll get back to you guys after I get back next week. Thanks again for all your input, cockiness or not.

[Sunking]

What's the best battery configuration?

To use all your batteries 24 volts. To extend battery life and efficiency 48 volts

You say it's so dangerous with no explanation why.

Answered that a few times and by others. CURRENT.

1000 watts at 12 volts is 100 amps
1000 watts at 24 volts is 50 amps
1000 watts at 48 volts is 25 amps.

A 1000 watt 12 volts requires a minimum #4 AWG very expensive wire only for short distances. More than 10 feet bigger more expensive wire. It requires special tooling (hydraulic compression) , training, and heavy connectors to . It also requires frequent inspection of loose connections and poor termination on cables. Failure to do those things will lead to a meltdown and or fire.

EV9MeltedTerminal.jpg

The issue is resistance and current flowing through the resistance of loose connections and poor wire terminations. On efficiency side the same issue, resistance. The resistance in wiring causes power losses as heat in wiring and connections. Less current means lower power losses or higher efficiency. 24 volt systems are 400% more efficient than 12 volt systems for a given power level on a given wire. A 48 volt system is 1600% more efficient.

[paulcheung]

Less than 800 watts inverter you can use 12 volts, 800 to 1500 watts 24 volts, over 1500 watts inverter 48 volts. Those are the best configurations.

When you draw more than 50 amps current from the battery bank, you need some big wires and when you reach to 100 amps it is hard to terminate the end properly unless you have the right tools and experience. many thing can go wrong when you dealing with high current, slack connection can cause fire.

[Jaust]

How many times can I say I'll worry about the solar later? What's the best battery configuration? You say it's so dangerous with no explanation why.

[Sunking]

Sunking, I wish you would have read the threads. I've said multiple times that this is the way I bought the cabin. I've asked for your help to help me rectify this problem and you said you want nothing to do with helping me. So I'm asking for help from someone that will tell me what the problem is and to help me. I respect the knowlege you have and wish you were on my side but since you're not I need help. That's all I'm saying. I personally would not tell someone that what you have is do dangerous that I don't want to help you make it safe.

Read my lips. 48 volts. Loose 4 batteries. 400 watts of panels (grid tie panels, not battery panels) , and a Midnite Solar Kid controller. Buy a 48 volt inverter and run everything off 120 VAC. In addition buy a good Golf Cart 48 volt battery charger to run off the genny. Its that simple.

[Jaust]

Sunking, I wish you would have read the threads. I've said multiple times that this is the way I bought the cabin. I've asked for your help to help me rectify this problem and you said you want nothing to do with helping me. So I'm asking for help from someone that will tell me what the problem is and to help me. I respect the knowlege you have and wish you were on my side but since you're not I need help. That's all I'm saying. I personally would not tell someone that what you have is do dangerous that I don't want to help you make it safe.

[Sunking]

I'm just wondering what is so dangerous that it scared Sunking away. I'm sure he's so used to everyone bowing to him and his knowledge. But after I explained my setup and asking what I can do to make it right that instead of helping he says yor on your own. I'll probably get thrown out of the forum but he can kiss my ass.

Your skin is real thin. I will not help you if you intend to use 12 volts. I don't want any part of you injuring yourself, others, or burning your home down. I have taken an oath as a professional to do no harm. Someone else can help you do that and be held liable. Not me. Someone will be around to explain it to you later. Who ever told you it was a good idea or set it up that way is not knowledgeable and did not know what they were doing. If they had would know the dangers of 12 volt high current systems.

I will give you one hint. a 2000 watt inverter at 12 volts takes 200 amps of current. A large luxury home with all the electrical bells and whistles does not draw that much current. Possible if they demanded 48,000 watts, but it never happens. Those houses have much larger service wires than you do. Walmart stores do not draw that much current. Nor does an oil refinery which draws million of watts at a time. They do not do it for 2 reason. Big waste of money and dangerous. That ought to give you something to think about.

[Jaust]

Ethanol you both for the info. I have learned slot in a short amount of time. I will definitely look into rewiring either 24 or 48. I'm still wondering what is so dangerous about the setup now. The guy that set it up was no dummy. I'm just wondering what is so dangerous that it scared Sunking away. I'm sure he's so used to everyone bowing to him and his knowledge. But after I explained my setup and asking what I can do to make it right that instead of helping he says yor on your own. I'll probably get thrown out of the forum but he can kiss my ass. What kind of a responce is that? I've been on another forum that has given me great advice. I had to laugh when I saw his name come up. They warned me about him. I should have listened.

[mschulz]

It is a vacation cabin, he doesn't use it every day, so 20% for 5 days it is waste of money. He can safely discharge to 50% and still last him few years as the cycle count on each year is less than 50 cycles. Remember battery will die in a few years even you don't use it at all.

also the C/8 rate is also too much as he has the whole month to charge back the battery, the solar power just sit there and wasted, He has generator to charge the batteries if is needed.

Again the generator need to start and run for hour or so every month or two, so he can use that to stir up the electrolyte in the batteries.

Paul - like I said at the bottom, it is an estimate only. We all think differently about cycling as well - what is too much or a waste of $$.

[paulcheung]

Since you have the batteries, wire them up in 1 series to make 48 volts. Your efficiency will be greatest.

I bet those batteries are 220amp. So useable power =220amp x 48v * .20 = 2112 watt hours. This will draw down your new bank to only 20%.

Now let's find out what draw and charge you need. We are going for c/8 on those.

It is a vacation cabin, he doesn't use it every day, so 20% for 5 days it is waste of money. He can safely discharge to 50% and still last him few years as the cycle count on each year is less than 50 cycles. Remember battery will die in a few years even you don't use it at all.

also the C/8 rate is also too much as he has the whole month to charge back the battery, the solar power just sit there and wasted, He has generator to charge the batteries if is needed.

Again the generator need to start and run for hour or so every month or two, so he can use that to stir up the electrolyte in the batteries.

[mschulz]

Since you have the batteries, wire them up in 1 series to make 48 volts. Your efficiency will be greatest.

I bet those batteries are 220amp. So useable power =220amp x 48v * .20 = 2112 watt hours. This will draw down your new bank to only 20%.

Now let's find out what draw and charge you need. We are going for c/8 on those.

220amp / 8 = 27.5 amps. This is what you should put in and take out. So your panels and inverter should be no larger than. 27.5 x 48v =1320 watts.

This tells you that if you wire 8 of yor batteries together for 48 volt, yor inverter charger needs to be 1200-1400 watts at 48 volts.

Like I said before, dump all your 12 v stuff and run it off your new inverter.

***note that this does not account for any days of no sun and if you are using the cabin on cloudy days you will need to run your generator each day to charge your batteries. This is an estimate only. Now you need to get the actual size of your batteries and your usage to see if it will work.

[paulcheung]

It is all depend on the amount of power you need in 24 hours period. I think 24 volt battery system is adequate for a vacation cabin, still it is the amount of power that matters. When you find out the amount of power you need, we will be able to advise you properly.