Solar panels and volt readings.

[86Dolphino]

I been goofing around with solar panels. I currently have a 135watt kyocera panel with a Sunforce 12v 30amp digital charge controller.  

 

My question is picked up another panel was told its 175 watt 12v panel, but when I hook up my volt meter to it, it gives a reading of about 33.3 volts. That's way over 12v. Is that ok or was I miss informed on this panel being 12v.

 

I'm worried it's too many volts for my 12v charge controller and battery. 

[WME]

You got a serious mismatch. Any label on the "new" panel?

A 12v panel usually has 22v open circuit. 33v seems to be a 24v panel. Your controller max v is 25v.

Sounds like a nogo

[Maineah]

33.3 volts seems a bit high it's not wired to the other panel also in series? Either way the controller with take care of it if they are not series wired usually they are in the 20-25 volt range in direct sunlight so if it's not noon on a bright day it sounds like they are series wired because thats 16+ volts per panel more like I would expect.

 

[86Dolphino]

No labeling  on the new panel. 

Which is a bummer. 

It was about high noon and do not have it worked up yet. Just had it laying in my driveway when I tested it.

 

Maineah are you saying I can still wire it in just not together but separately to the charge controller?

I'm going to see about exchanging it

[Maineah]

 No I would not use it with a 12 volt controller that is too much over the top. What I was think you had it wired to the other one in series but if it was sitting in your yard than that's too much voltage for your 12 volt controller It most likely is a 24 volt panel. If you are stuck with it buy another controller for 24 volts lot cheaper that a panel. Me I would start the generator charge the batteries enjoy the AC and run the microwave!

[DanAatTheCape]

can you light it up and read what voltage is really coming ?

[86Dolphino]

Yes you can. That's how I found out it was way over 12volts. I ended up exchanging them for 3 75 watt 12v panels. I'm trying to determine how many watts I really need. 

 

Right now I have a 135watt panel but I now could add 225 more watts giving me 360watts but I'm not sure i need that much. 

 

I do want to add a 12v tv with a built in DVD player but other than that, that's it. 

 

 

Right now I'm going to get two 6 volt batteries. 

Edited November 25, 2018 by 86Dolphino

[Maineah]

I have a camper with two group 24 batteries (160 amps) I can go indefinitely even with a couple days of rain with a 100 watt panel every thing is led no exceptions there is an accumulator on my water pump (less run time). A Fantastic fan set on low. I have a small inverter to watch TV (I'm not a big tv watcher so time is limited) listen to sat. radio I don't camp when it's cold enough to need the gas heater but could for a day or two. I can run my ham radio gear and charge things like phones on 12 volts. Now here is a catch my panel is ground mount I made a custom frame for it that allows me to elevate it and turn it so I get sun from dawn to dusk, a roof mount only get full sun at midday granted that's max sun but during the remainder of the day I can do pretty much the same so I get a good bit longer charge time. The panel has a 15' #10 power cord and plugs directly into the battery bank the controller is mounted on the panel so it's self contained. It folds flat and lives on the bed in transit. The bottom line if you need to bring the house with you you will need a lot of power but every day most stuff is getting more and more efficient and if you keep the demand down you can get by with very little.

[WME]

Kinda, sorta wag for solar systems sizing. 1 watt of solar for 1 amp hour of battery. Sooo how big is your proposed battery bank??

[WME]

LOST POSTS

1. Make sure your roof is big enough to support your panel wattage.

2. Balance is the thing

3. Big battery, smaller panel makes your system an extenda-stay

4. Big battery, big solar..perpetual motion

5. Controller is important, max panel charge amps should be less 20% of battery capacity.

[Gulfstream Greg]

I have always been under the impression that panels should be wired in series for better charge efficiency. Then select the correct controller for the voltage supplied from the in-series panels.

An expert I am not, so anyone have the info to fill in the blanks? Some panel/controller 101?

[WME]

RV solar 101😁

https://amsolar.com/rv-solar/support/

Remember grasshopper its all about balance

Edited November 29, 2018 by WME

[Maineah]

Generally big arrays are to reduce cable size and voltage loss with higher voltage, above 600 volts it starts to get in to a different realm. Because of the relative short cable run a mobile aray it's not real important a #10 cable will carry 30 amps 2 100 watt panels maybe on a bright day maybe 16 amps tops so the loss is not really great when the regulator is at the end because of the 20+ volts from the panel. When you start adding batteries to the mix their output is a different issue they are capable of large current. I use a 25' cable on my portable aray it is a #10 I see little or no loss and it is already regulated down to battery voltages as the controller is at the panel,

[WME]

Parallel thought... If you have a long distance between the panels and your battery, place the controller as close to the battery as possible. A .1v drop on the 18v coming from the panel is no big deal. A .1 drop between the controller and battery is a big deal and has a big impact on the battery being fully charged. 

[Maineah]

That is true but in the case of a Toy home it's pretty hard to get too far away from a battery though!

[frontboat]

u need mppt controller or u could  fry the controller . i did

[Maineah]

PWM's work but they are RF noisy The MPPT's are definitely more efficient and pretty much standard now the  technology marches  on. 

[86Dolphino]

so I went into my Dolphin today. and was looking at my charge controller and noticed it said 17.6 volts. how is that? do these charge controllers go bad? after my furnace ran for about 5 to 10 min I could def tell my battery was draining. I feel like it roasted my battery.

[WME]

1. Check the water level in the battery.

2. Get a good VOM and check the actual voltage at the battery.

Charge controllers can go bad the same as most electronics. 17.6 sounds almost like a shorted controller that is allowing full panel voltage to the battery...Silly question are you sure it was 17.6, not 12.6

[86Dolphino]

I just doubled check, it's now showing 20.4. I have all LED lights inside and it wont even turn on a light. the original (but generic) battery level indictor says 1/2 batt. when I started this thread 11/6/18 my battery worked good.  I don't think I installed anything wrong. red to red black to black. I first noticed it about 3 weeks ago. but didn't pay much mind. now wish I did. 

 

 I could not check the volts at the battery (ME I think VOM is Volt ohm meter) its dark outside and raining pretty good today.

[WME]

Take a flashlight and go out and disconnect all the wires going to the - terminal on the battery. Tomorrow in the daylight we will help you check things out.

Was the Rv plugged into shore power?

Yes VOM=volt ohm meter

 

[86Dolphino]

ok will do and no its not connected to shore power

 

thank you

[Maineah]

13 hours ago, 86Dolphino said:

so I went into my Dolphin today. and was looking at my charge controller and noticed it said 17.6 volts. how is that? do these charge controllers go bad? after my furnace ran for about 5 to 10 min I could def tell my battery was draining. I feel like it roasted my battery.

From the panel itself that's ok they can run 22 volts on a good sunny day, from the output of the controller that's high check it directly at the battery and see what you get. The furnace sucks up a good deal of power and will kill a battery in less than 2 days. Make absolutely certain you have the controller connected properly (input/output) if it isn't you will see high voltage at the battery. Batteries are resistive but at 22 volts it can cause damage to the battery over time. The controllers work by turning on and off, the time they stay on is how they regulate the longer the time the greater the charge.

[WME]

Mr. Dolphin status???

[86Dolphino]

Folks I'm sorry for flaking out. I won't give a bunch of excuses.  

 

I have pulled the 12v coach battery took I took it down to batteries plus who said it was shot. Build date on battery was like Nov 2017.

 

While I was there I bought two new Duracell 6v batteries.  

 

I don't trust me my charge controller.  I'm wondering if anyone can direct me to a decent charge controller for 120 or less these new batteries. 

 

I cant get the forum to upload my photos so here is a link of what batteries I got. 

 

 

https://www.batteriesplus.com/battery/sli/bci-group-gc2/sligc115

 

 

 

[WME]

OK tomorrow go out at noon and measure the voltage from each panel no controller just the max voltage the panels are generating.

I have the same 2 batteries and a 280 watt panel.

Edited March 16, 2019 by WME

[86Dolphino]

Ok alarm is set for noon 

[Maineah]

Solar controllers usually are PWM inexpensive and work well there are some PWM controllers that are designed to reduce RF noise a little more expensive. You do not need to buy a controller that has a high current rating thinking it's better it isn't it just will handle more current at a greater cost. Two things you need to know when testing power output voltage and current. A 12 volt panel will make around 22 volts on a normal sunny day that's step one, some are series wired and may double the voltage it's what you need to know otherwise you will cook the controller. Next is current. This will require a meter that can measure current output, many off the shelf will do that it is the same basic ideal with the two panel leads this time with the current measurement the panel will eventually will be short circuited the meter will read in amps. Most meters will sink up to 10 amps. Test each panel add up the current and apply it to the controllers rated current capacity that with a little head room will determine what you will need to buy. No sense buying an expensive controller that will handle far more current than what you need they all work exactly the same. Applications that use multiple panels usually are series wired in the case of a small array generally they are not so your last test would be over all voltage with all of the panels wired if you come up with voltage greater than 22 volts more like 44 they are serised wired and will need a 24 volt controller. Small controllers are as cheap as $15 what I would look for there is lack of noise suppression they often make a motorboat type of noise in you FM radio so maybe a $30 one of the same rating might be a little better.

[86Dolphino]

I just hooked the volt meter to each one of my panels 

 

My 135w kyocera (I may have spelled that wrong) is running steady at 20.4v

 

My 75 watt flex panel is going from 13.77 to 13.80

 

It is a good clear day phone says its 50 degrees but feels like 70 in the sun.

[86Dolphino]

Maineah

 

I am unable to figure out how to check current.  I have attached a pic of my cheap meter maybe you can tell me what setting it needs to be on and how

 

Found if I reduce the pic size on my camera the forum will let me upload a photo  

[WME]

Your flex panel is zapped. The other panel is a functioning 12v panel.

A 20 amp MPPT controller will handle about 250 watts of panel power. Look for one that has 3 stage charging. 

I dont have this controller but it has all the needed features needed    https://www.ebay.com/itm/20A-MPPT-Solar-Charge-Controller-Max-Panel-100V-Common-Negative-12V-24V-Auto/143046291911?epid=11023330324&hash=item214e3931c7:g:bcQAAOSw5qdcDdfm.

 Basic perfectly usable PWM controllers run in the $10-20 range. Basic MPPT controllers are in the $25-35 range.

Saw the lastest post that meter will NOT measure DC amps

[Maineah]

It really is hard to tell what the meter reads in amps if the line under the "A" is flat it will read DC amps if it has a wiggly line it's AC and won't work.  It order to do that the panel wires need to be joined together then the clamp clips over one wire only and the scale would be 20 if it will read DC. Your flex panel is toes up and joined to the other panels will drag them down too it's about a 3 volt deficit with the pair and that's big. But before your toss it move your meter leads from ext to volt/ohms and try again. Just looked up your meter it won't work for DC current it's strictly AC current so you can't read amps. Your 135 watt panel is doing fine if you move it a bit it may even come up but 20+ volts is fine and frankly if you don't go overboard on power demand it's more than enough. I run my rig on one 100 watt panel and two batteries @ 160 amps.

[WME]

Remove all the wires from your house batteries. Check the battery voltage, resting, it should be in the 12.5-13v range. Then hook up your controller to the battery and panels. Do NOT  hook any load to the batteries. Just watch the battery voltage. Anything over 14.7 v means a bad controller.  Replace it if it acts badly otherwise let it charge for a few days

If it's all good after a few days, hook up the loads and see what happens

 

[86Dolphino]

Makes me nervous to run this sunforce charge controller again. My current charge controller seemed to work fine until I added that 75w flex panel. 

 

When I seen the low volts of the flex panel i pulled it down off the coach. 

 

I spent some of the day building a new battery box to hold both 6v.

 

I have 2 other 75w flex panels and they are around 13 to 14 as well. I got them used very used apparently  haha. 

[WME]

8 hours ago, 86Dolphino said:

Makes me nervous to run this sunforce charge controller again. My current charge controller seemed to work fine until I added that 75w flex panel. 

 

 

1

 

I understand your caution. That's why I suggested small steps. I think that the bad panels and poor battery combined to cause your problems.  There is a 50% chance that your Sunforce is OK. 

It looks like you could parallel all the flex panels and charge a battery without using any controller.