Need help wiring 12v solar project

solarpowernovice

Before I attempt to wire everything I want to make sure this is correct...I left out grounding in the diagram to make it easier to read. Is this an acceptable way of wiring this system?

I have three 270 watt solar panels in Series going to a 15 amp breaker, then to PV+ on the Midnite Classic 150.

The negative from the PV panels goes directly into the PV- of the Classic.

From the Battery+ on the Classic with #4 conductor going to a 100 amp breaker, then to the positive post on the battery bank.

The Battery- on the Classic to the negative post on the battery bank with #4 conductor.

From the Positive post of battery bank (four 6v golf cart batteries) #2/0 conductor going to a 250Amp breaker, then to the positive of the inverter.

From the Negative post on battery bank with #2/0 conductor going directly to the Negative of the inverter.

Attachment not found.

Cariboocoot

Re: Need help wiring 12v solar project

With one small change: your batteries are 'laddered'. As such the two strings won't share current evenly. You need to connect them 'diagonally'. See diagram here.

solarpowernovice

Re: Need help wiring 12v solar project

okay this guy in this video was telling me to put the positive and negative on the front 2 batteries http://www.youtube.com/watch?v=VYhH6-hcu8U at 3:36 good thing i checked first (and keep in mind he has his own website where he sells solar equipment)

Cariboocoot

Re: Need help wiring 12v solar project

solarpowernovice wrote: »

okay this guy in this video was telling me to put the positive and negative on the front 2 batteries http://www.youtube.com/watch?v=VYhH6-hcu8U at 3:36 good thing i checked first (and keep in mind he has his own website where he sells solar equipment)

Just because some has youtube videos and sells stuff doesn't mean they know what they're talking about. In fact it often means they don't.

The idea behind the diagonal wiring is that it keeps the resistance fairly equal on both strings. Laddered: one string is connected directly to the positive and negative cables, the other has the extra added resistance of two interconnecting wires. Diagonal: each string is directly connected to one power cable and has one extra wire each to the other.

solarpowernovice

Re: Need help wiring 12v solar project

yes ive learned to not believe anything i read or see in videos online anymore LOL thanks alot!!! I'm going to get my cables cut now

zoneblue

Re: Need help wiring 12v solar project

You look like you are ont he right track. Seeing as you have the mini dc (good choice), you may as well add a 500A shunt (and negative bus) and use that to connect the negatives. That will also give you the WbJr, SOC, EA and other nice things for very little money. Mount classic above minidc, make your wiring cleaner etc.

Do you really need 100A for the classic breaker?

solarpowernovice wrote: »

Before I attempt to wire everything I want to make sure this is correct...I left out grounding in the diagram to make it easier to read. Is this an acceptable way of wiring this system?

I have three 270 watt solar panels in Series going to a 15 amp breaker, then to PV+ on the Midnite Classic 150.

The negative from the PV panels goes directly into the PV- of the Classic.

From the Battery+ on the Classic with #4 conductor going to a 100 amp breaker, then to the positive post on the battery bank.

The Battery- on the Classic to the negative post on the battery bank with #4 conductor.

From the Positive post of battery bank (four 6v golf cart batteries) #2/0 conductor going to a 250Amp breaker, then to the positive of the inverter.

From the Negative post on battery bank with #2/0 conductor going directly to the Negative of the inverter.

Attachment not found.

solarpowernovice

Re: Need help wiring 12v solar project

I already have the 100 amp breaker... i hope its okay to use it

Cariboocoot

Re: Need help wiring 12v solar project

solarpowernovice wrote: »

I already have the 100 amp breaker... i hope its okay to use it

As long as the wire is capable of greater current it is. Example 100 Amp breaker & 4 AWG wire yes, 100 Amp breaker & 8 AWG wire no. The idea is if the current goes too high the breaker trips before the wire fries.

solarpowernovice

Re: Need help wiring 12v solar project

Okay I've wired everything just like in the picture i showed you but I haven't actually connected the inverter cables to the batteries yet or the solar panels to the wire i have coming from the 15 amp breaker. Should I hook up the inverter first and then hook up the solar panels? Which one should i turn the power on first, the inverter or the charge controller? Also... should i put the inverter lug on the battery post first and then the charge controller on top of that, or does it matter?

I have to do all of this on the weekends so its been taking me a long time. I plan on adding a shunt and negative bus bar later, I just want to get all of it hooked up now to get the batteries charging and so on...

Cariboocoot

Re: Need help wiring 12v solar project

The only part that really matters is connecting the controller's output to the batteries before connecting the PV input. This is a wiring convention: not all controllers need to be connected this way but there's not a one that will 'object' to it whereas connecting the PV first will damage some controllers.

Other than that, the controller doesn't affect the inverter nor does the inverter affect the controller. There are systems that have one but not the other and work fine.

If anything getting the batteries charged should be a priority; you don't want them sitting around self-discharging while you work on other things. I normally will connect the charging first and make sure the batteries are up to snuff before activating any loads. Good idea to know you can put the power back before you take it out.

solarpowernovice

Re: Need help wiring 12v solar project

okay thank you I have had the batteries almost 2 weeks now i want to charge them today so we will be hooking it all up now

BB.

Re: Need help wiring 12v solar project

It really does not matter which you hook up first (charge controller, inverter, etc.)...

My suggestion. disconnect the cables at the load (charge controller, AC inverter, etc.).

Connect up the battery bank and measure the voltage at the loads (color code the cables, i.e., a few wraps of black and red tape where the cables connect to the loads). Double check polarity of the load connections. Disconnect battery (or turn off breakers), then connect up loads and power up (if your "bus connection" is at the battery, be very careful of sparks when you make your power connections. It does not take much of a spark to light off the hydrogen in the battery cells).

DC loads hooked up with reversed polarity--Many times--Are not very forgiving.

-Bill

solarpowernovice

Re: Need help wiring 12v solar project

The only grounding rod that lowes sold was 8 feet long... do i need all 8 feet of it or can i use half of it and the other half for my generator?

Cariboocoot

Re: Need help wiring 12v solar project

A grounding plate might serve you better: http://www.homedepot.ca/product/galvanized-ground-plate-c-w-connector/910158

Normally ground rods are 10' in the ground, with 5' being the minimum.

solarpowernovice

Re: Need help wiring 12v solar project

how deep do i bury one of these ?

Cariboocoot

Re: Need help wiring 12v solar project

solarpowernovice wrote: »

how deep do i bury one of these ?

Ah. Tricky question. It depends on your soil conditions. Ideally it will be in damp soil at the driest time of the year. That may not be easy to determine, but it's usually simple enough to dig a hole and see what the soil is like and go deeper if it appears too dry, as opposed to trying to drive a rod - and possibly hitting a rock.

solarpowernovice

Re: Need help wiring 12v solar project

i have a IOTA dls-90amp 12v battery charger (and 10 feet of #2 wire but, no breaker ). could I use this with my generator to charge the batteries until I get all the solar components hooked up and grounded? Or can i use my normal automotive 12v 5/10/50amp fully automatic charger/starter maybe ? This way I can have time to buy the grounding plate instead of the grounding rod I have. Theres also no sun today and I want to charge the batteries to keep them good... i bought them brand new about 2 weeks ago four Interstate 232 amp hour golf cart batteries

Cariboocoot

Re: Need help wiring 12v solar project

Yes the Iota should charge them fine, especially if they are not severely depleted. Even though it may not reach 100% it will keep them above the level where sulphation sets in.

Grounding is not essential for operation. It is for safety should something go wrong. Mobile applications, for example, can not be grounded because it would be impractical. Don't worry about it too much. If the solar can be up and running without a ground rod/plate go with it.

solarpowernovice

Re: Need help wiring 12v solar project

okay thanks. Does the iota NEED a breaker or can I just use it without one for this one time? If it absolutely needs a breaker i'll just wait until tomorrow or whenever the sun comes out and use the panels ungrounded... This is for a mobile application, I grounded all the components to the ground bus bar then to the frame of the enclosed trailer. The grounding bar/plate was going to be used strictly for the solar panels because they're not attached to the trailer.

BB.

Re: Need help wiring 12v solar project

There is the cost/benefit way of looking at Safety... If there (heaven forbid) is a failure in the Iota's output (shorted components) or in the wiring from the bank to the Iota--And there is not much to burn (concrete floor, charger wiring does not pass over flammable objects), and/or if the cost of failure is acceptable (damaged battery bank)--Then you can run the risk and be OK (I have not heard of an Iota output shorted/failure--But I am not in the business, so it would only be something I have read here anyway).

If this is your house and there is a wood sub floor, using plywood to mount devices, etc... The chances of failure are still small--But the cost of failure is high.

I have seen battery cables glowing red hot (old 1950's pickup with battery under floor and the latch spring failed and fell across the battery). Lots of smoke and glowing steel spring. And having to run back into the shop to grab something to pull the spring off the top of the battery.

Most cabin/home battery banks are many times larger than an automotive battery and can supply 10x or more current into a short circuit and have many times more AH available (in a car, the old assumption was the battery would go dead before the short circuit would light off the starter motor cables).

It is a tough call--Realistically, you could install the Iota without a fuse/breaker and nothing bad would happen for a 100 years.

Practically speaking, we have thousands of folks reading here, and some how/some where, something will go wrong for that one person/family.

It it was me--I would connect without the fuse/breaker on the battery bus and get the things charging (be very careful of sparks near battery cells--oxy/hydrogen gas explosions are not pretty)... And I would not leave them alone/go to sleep (I would be around the place--If I saw/smelled smoke, I could do something). I would also have a fire extinguisher, and something to cut the cables if needed (ax, bolt cutters, etc.) so I could stop the current flow if needed. Large battery banks contain a scary amount of power.

I have done many stupid things over the years and, obviously, survived them. We have very skewed ideas of what is risky or not (feel much safer with us driving the car to work vs turning our lives over to an airline company and captain--But air travel is much safer).

I cannot recommend you do something that would put you at risk. Evaluate the risk/reward for your project. And be conservative--Short term risk (charging a battery bank for a 1/2 day) is one thing... Your off grid/backup power system running for decades into the future, is another.

-Bill

solarpowernovice

Re: Need help wiring 12v solar project

Okay I think I'll just use one of the solar panels ungrounded for now, to get the batteries charging. All the components are grounded too the trailer frame already. This seems like a safer option to me... What about you?

BB.

Re: Need help wiring 12v solar project

It only helps if there is a lightning strike (or near strike). Otherwise, no issue electrically.

-Bill

solarpowernovice

Re: Need help wiring 12v solar project

ok i wired just the charge controller up to the batteries... I have PV+ from panels going into the 15amp breakers LINE side then out to PV+ of CC. I have the negative from panels connected directly to PV- on the CC, then from battery negative of CC directly to the battery negative post with #4 conductor, then from battery positive of CC to 100 amp breaker with #4 conductor to battery positive post . I turned on the charge controller first and selected solar and set date and everything, then I turned the panel breaker on. The problem is I am not getting any power to the batteries its saying 0 volts in with PV breaker turned on, and when i turn PV breaker off it goes to 5 volts... I have 1 250 watt panel hooked up to it right now and from what i can tell its all hooked up right and the sun is out. Charge controllers mode is set to ON not OFF...

unseenone

Re: Need help wiring 12v solar project

What do you get if you disconnect the PV cables on the Charge Controller side, and put a multimeter on the +- for DC Volts on the PV Cables from the panel(s)? At the panel(s)?

Cariboocoot

Re: Need help wiring 12v solar project

solarpowernovice wrote: »

ok i wired just the charge controller up to the batteries... I have PV+ from panels going into the 15amp breakers LINE side then out to PV+ of CC. I have the negative from panels connected directly to PV- on the CC, then from battery negative of CC directly to the battery negative post with #4 conductor, then from battery positive of CC to 100 amp breaker with #4 conductor to battery positive post . I turned on the charge controller first and selected solar and set date and everything, then I turned the panel breaker on. The problem is I am not getting any power to the batteries its saying 0 volts in with PV breaker turned on, and when i turn PV breaker off it goes to 5 volts... I have 1 250 watt panel hooked up to it right now and from what i can tell its all hooked up right and the sun is out. Charge controllers mode is set to ON not OFF...

Almost what unseenone said, only disconnect the PV and check the Voltage at the BATT terminals of the charge controller. You should read battery Voltage there. If not something is wrong with the wiring between the controller and batteries.

solarpowernovice

Re: Need help wiring 12v solar project

Can I leave the battery terminals of the charge controller screwed into place and take the reading(leaving the breaker on of course)?
On the charge controller status menu it says 12.2 volts battery voltage. If I am reading a battery voltage on charge controller terminals with a multimeter, then whats the next step I should take to resolve this issue?

Cariboocoot

Re: Need help wiring 12v solar project

solarpowernovice wrote: »

okay can I leave the battery terminals of the charge controller screwed into place and take the reading(leaving the breaker on of course)? On the charge controller status menu it says 12.2 volts battery voltage. If I am reading a battery voltage on charge controller terminals, then whats the next step I should take to resolve this issue?

Yes; leave the battery connected and ON to check battery Voltage at the controller's output. It should read properly. if it doesn't that problem has to be found and corrected first.

It rather sounds like the PV (or possibly the battery) is backwards, btw. Keep an eye out for a little '-' in front of the numbers - it can be easily missed on some meters.

Second step is to read the PV Voltage (and polarity) with the PV not connected to the controller input. It should read Voc. When the PV is connected to the controller correctly the battery Voltage should not drop and the current should come up.

solarpowernovice

Re: Need help wiring 12v solar project

When I hooked the multi meter to the battery negative and positive on the charge controller, the hand on the multi meter spiked to the full ammount ( when set to 10vdc). The only other 2 settings on my multi meter are 50vdc and 150vdc. The sun went down and I couldnt test the solar input I'm probably going to call a local guy who builds and sells 12v portable solar generators and see if he will help me out.

Cariboocoot

Re: Need help wiring 12v solar project

solarpowernovice wrote: »

When I hooked the multi meter to the battery negative and positive on the charge controller, the hand on the multi meter spiked to the full ammount ( when set to 10vdc). The only other 2 settings on my multi meter are 50vdc and 150vdc

Okay in the case the next step is to get a better meter. I'm not kidding. Whacking one of those analog ones with V that's off the scale is not good for them. Nor is reversing polarity and pinning the needle backwards. What's more they are hard to read (try finding 14.5 Volts on that 50 Volt scale) and not very accurate.

solarpowernovice

Re: Need help wiring 12v solar project

I think it may be time for me to call a local solar expert tomorrow and have them hook it up for me, unfortunately.

solarpowernovice

Re: Need help wiring 12v solar project

can I hook up my regular 12v automotive charger to the wall and then series 2 of the golf cart batteries and charge them for a few hours? My regular charger has a 5amp and 10amp deep cycle switch on it, but it has clamp on connectors.