# Solar problems



## coates776 (Sep 4, 2015)

My back up solar would appear to be no good. It drops from 12.5 to 10.5 in 4 hours of use and can take a week to charge back to 12.5

My electrician son says it's the panels and have appeared to rusted. He said they are designed to sit on caravans and be brought in at night.

What sort of panels should I have purchased. I have 5. 120v panels currently hooked up to 5 expensive batteries.


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## Slippy's-Attorney (Sep 23, 2015)

How many batteries do you have? if you have more then 1 you could have a bad one

most 12 vdc panels put out much more then 12 vdc.. the controller controls the out put to the battery so they do not get over charged.

if the panel(s) are putting out enough and the controller is pass through enough.. the battery is the problem

also if you have multi panels..a bad panel can effect the total out put also


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## Slippy's-Attorney (Sep 23, 2015)

coates776 said:


> My electrician son says it's the panels and have appeared to rusted. He said they are designed to sit on caravans and be brought in at night.


I have never heard of this.... I think you need a new electrician...


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## Mad Trapper (Feb 12, 2014)

Get a electric tester. Check each panel for output voltage individually.

Check each battery for volts after charging with a plug in charger, and putting a load on it. Do all the cells have water?

Can also use a ohm meter to check all connections.

Did you mean 5 12V panels, hooked to 5 12V batteries in parallel through a charge controller?

Do you run 12V off the system or have 120V inverter?


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## Joe Smith (Aug 21, 2015)

Hello,
I would start by checking the batteries. Batteries will, when fully charged have up to about 13.5 volts. This can be deceiving though, charge them fully then put a load on them-I usually use just an old car headlight. Check the voltage of the battery again with a volt meter. If the battery has lost voltage-drops to 10.5, then the battery is not doing well. 

Are the batteries maintenance free type with no removable top caps? If they have caps on top that are removable and you can see the individual cells they must be topped off with water, make sure to use distilled water, there are no trace mineral elements. Do not add too much, fill to the appropriate level.

On a sunny day have you checked to see the voltage output of the panels? Your son could be able to help you. Check the output with a volt meter.

So if you've checked the batteries, individually, and they are good, and the output of the panels is good, then your controller has a problem. I am used to working with motorcycles and smaller stuff like that but they will have a "regulator/rectifier" that regulates voltage to the battery, and changes the current from AC to DC. I have seen these go bad and overcharge/boil the battery, and since they are also connected to the ignition it affects engine performance.

As for the rusting, I don't know. If I bought something I want to use it. Can they be cleaned and coated with something. Oh, and caravans? You in merry olde England? Let us know from time to time how it's going there, we're curious.


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## 8301 (Nov 29, 2014)

coates776 said:


> My back up solar would appear to be no good. It drops from 12.5 to 10.5 in 4 hours of use and can take a week to charge back to 12.5
> 
> My electrician son says it's the panels and have appeared to rusted. He said they are designed to sit on caravans and be brought in at night.
> 
> What sort of panels should I have purchased. I have 5. 120v panels currently hooked up to 5 expensive batteries.


Coates,,, It's been a while so remind me about your battery bank amp capacity and what charge controller are you using. That will allow me to suggest a panel wattage for most efficient battery charging at a C/10 to C/8 rate to protect your batteries.

Panels, even good ones, can delaminate inside and allow the wiring to corrode. Panels also have diodes in the back (prevents the panels from discharging your batteries at night but they rarely go bad. Panels can rarely be repaired, replacement is usually required.

Assuming you have lead acid batteries and a good hydrometer test all of the cells of the batteries and post your specific gravity ( SG ) readings here when the batteries are fully charged. Different batteries have different from the factory electrolyte charges but you want to see at least 2.165 in each cell on a fully charged and healthy battery. To be more precise about SG charges most battery manufacturers list their SG rates on the internet and may be worth looking up.

example, my Crown batteries have a factory SG of 1.277 when fully charged instead of the 1.265 SG I mentioned earlier.

Simply using a open circuit voltage measurement is a poor method of testing a batteries health.


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## 8301 (Nov 29, 2014)

P.S. If you electrician thinks solar panels need to be brought in at night you need a new electrician. Well made solar panels have 20+ year warranties mounted to your roof in the rain and occasional hail. They are required to be capable of withstanding 1" hail at 55 mph. 

Solar World hail testing procedure:.
Hail Impact Test. Replicates a natural hail storm by dropping a 1.1-pound, one-inch steel ball onto solar panels from a height of 13 feet. Then we repeat this up to 20 times in the same place on at least 11 different points of impacts.


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## coates776 (Sep 4, 2015)

Attached is a photo of the installed system and attached is also a pic of the panels I got on eBay

Son is electrician, a grade contractor. But this is his first solar set up


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## coates776 (Sep 4, 2015)

Just turned on inverter battery light on and it reads batteries 10.8


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## 8301 (Nov 29, 2014)

Ok, I'm going to assume that you have five 100 amp hr reserve 12v AGM batteries. Since you're using a PMW type controller which really limits how much of the power the panels make on a sunny day you'll need a bit more panels than if you had a MPPT controller and wire them in parelell instead of in series. If you want a relatively fast charge rate of C/7 which is about as fast as you'd want to charge a battery to help keep from shortening it's life too much from heat. C/7 rate for that battery bank is 900 watts worth of well positioned panels and a good controller.

You must charge at least at a C/20 rate so you must have at least 300 watts worth of good panels properly angled and that is the bare minimum to protect your batteries from undercharging although I'd like to see at least 480 watts worth of panels and a good charge controller to charge the battery bank I'm assuming you have.

We can get into derail rates and other variables but I'd need to know a lot more about your equipment. I do know that you have a PWM type controller so you need to avoid top of the line high voltage panels. Look for panels that put out about 17-20v and wire them in paralell or get better MPPT type controller.


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## coates776 (Sep 4, 2015)

This is the batteries they read 130


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## coates776 (Sep 4, 2015)

There are 5 panels. 120 each all linked together like the batteries


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## coates776 (Sep 4, 2015)

If you thought I had 5 100 w batteries and need 900w of panels being 180 w per battery but the battery size is 130 so what should the total on the panels be. I currently have 5. 120w panels being 600w


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## coates776 (Sep 4, 2015)

I don't think we'd have a charge controller?


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## Mad Trapper (Feb 12, 2014)

coates776 said:


> There are 5 panels. 120 each all linked together like the batteries


You batteries are in parallel, so that portion is 12V. You can't charge that with 120V.

Not sure what your "white box" does?

Doubtful panels are 120V, most likely 12V (ca. 17V in full sun if all are working O.K.) , that feeds your 12V battery bank.

What sort of loads are you drawing off this system? 12V DC or 120V AC? If 120V there is an inverter someplace in the system. Concerning loads, how many watts ( Volts X amps) are you drawing from the system?


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## Operator6 (Oct 29, 2015)

Few years ago a guy a few miles from me burnt his house down with solar panels and batteries. Fireman determined it wasn't installed correctly. 

Be careful ! Lol !


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## 8301 (Nov 29, 2014)

coates776 said:


> If you thought I had 5 100 w batteries and need 900w of panels being 180 w per battery but the battery size is 130 so what should the total on the panels be. I currently have 5. 120w panels being 600w


Since your five batteries are 130 amp/hr each 
390 watts of panels minimum
630 watts a nice compromise
1150 watts maximum to minimize heat damage from charging too fast

On a related but different subject. I've mentioned this before but I'll say it again. Having more than 3 batteries in parallel seriously risks damaging your batteries from uneven charging. If a person wants more amperage than 3 batteries can provide they either need larger batteries or lower voltage batteries.
Six good sized 2v batteries in series will make for a huge 12v battery and the batteries will have much more even charging than running the batteries in parallel.


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## 8301 (Nov 29, 2014)

coates776 said:


> I don't think we'd have a charge controller?


If you're using one of those cheap solar kits that is designed to hook to a battery it should have come with a PWM type charge controller to protect your batteries from overcharging. This controller must be able to handle the amperage your panels are producing.

390 watts @ 12v requires a 35 amp charge controller
630 watts @ 12v requires a 55 amp charge controller
1150 watts at 12v requires a 100 amp charge controller

While not super recommended I've heard of people using several smaller charge controllers, like 1 controller per panel. They must all be the same model of controller in an effort to have them roughly run the same charging algorithm.


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## 8301 (Nov 29, 2014)

coates776 said:


> If you thought I had 5 100 w batteries and need 900w of panels being 180 w per battery but the battery size is 130 so what should the total on the panels be. I currently have 5. 120w panels being 600w


five 120 watt panels
5 X 120 = 600 watts worth of panels so your good assuming you have a charge controller that can handle it. You may find there is a little charge controller attached to each panel. It will have at least 2 led lights on it. The little black box on the back of the panels with no lights is not a charge controller. It is where the wires go through a diode which all panels require.


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## 8301 (Nov 29, 2014)

Operator6 said:


> Few years ago a guy a few miles from me burnt his house down with solar panels and batteries. Fireman determined it wasn't installed correctly.
> 
> Be careful ! Lol !


DC amperage makes a huge electric arc. 5 batteries are capable of putting out over 3000 amps for a short time so no metal tools  around the batteries.
My batteries (eight 6v 395 amp) are stored in a vented plastic garden box from Home Depot. There is nothing metal stored on the shelf above the battery box and I use a plastic flashlight and plastic coated tools when working around them when the box is open.

There are 7 different sized breakers in the DC side of my system along with several shutdown boxes, all required by the 2014 NEC guidelines. If you have a solar circuit that runs into the house and you have a fire the insurance company may not pay if they can show you didn't follow at least the 2011 NEC guidelines. Many areas including mine don't require the 2014 guidelines but I built to that level since it wasn't too much extra for a ground mount system like mine.


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## coates776 (Sep 4, 2015)

Decided first thing am going to get box built around it as that is next on the list and picked up a good quality battery charger to keep them charged why I work on the panel issue


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