# I need help please =D



## razorback (Jul 17, 2012)

Hi there!!!

The only thing I know for sure about solar power is it comes from the sun. With that being said I have a question for a friend.

He has had solar panels on his roof for I know 4 years, I finally got around to asking him about them and I opened a can of worms that I could never imagine. When that happened I purchased the Solar Power for Dummies book, yeah that cleared things up.

And now here I am asking the true experts in the matter =D

The can of worms:

He has never been able to do anything but charge his power tool batteries with the solar panels. He had 1 (car) battery hooked up to the panels and that would charge, but that wasn't enough to run the Frig in the shop. I told him if I was guessing I would figure the 1 battery could not handle the load of a frig. So the other night I get a text from him of a frig with the lights on. He had added 3 more batteries, and the frig was running just fine (for 30 minutes that is). 

Here are some number's s\he texted me today when he asked about my Dummies book and if I had learned anything yet LOL!!! 

His words:

I was reading reviews of different books for help. I've got 4 12V batteries each with 25 amps but I can't power my frige that pulls just 280 watts and 2.5 amps. Obviously (and not surprisingly) I'm doing something wrong. According to an online conversion table 12v and 25 amps translates into 300 watts. So I can't figure out why 4 times that can't keep a durn fridge going.

Now again, I know nothing about solar power and I'm a blonde female so I have some pretty heavy issues stacked against me on understand anything you tell me. But I'm willing to learn =D

Thank You in advance for any help and info you can share!!!


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## LincTex (Apr 1, 2011)

Well, for starters, for the time being just consider the solar panels as "Battery Chargers".

The energy source is the batteries. They don't create energy, they only *store* it.

The inverter converts the battery power (DC) to the type of power the fridge uses (AC). 
It must be large enough to handle "starting" loads, not just "running" loads. 
It takes more power for a mount to get a motor started than it does to keep one going.

With me so far?

Is the fridge 12 volt, like from an RV/Camper? Or it a normal household fridge?

Let me guess one more thing..... your friend is using normal car "starting" batteries - - NOT "deep cycle"... am I correct?


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## razorback (Jul 17, 2012)

Yes it is a normal fridge and I'm asking about the batteries =D


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## razorback (Jul 17, 2012)

Yes he has deep cycle batteries

It's at the inverter part I start to get glassy eyed


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## razorback (Jul 17, 2012)

Just got this from him:

My set up will power the thing for about 30 minutes then go off so it can handle the initial load. And after that it shuts off and the batteries still show 12v

Does that help?


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## Viking (Mar 16, 2009)

LincTex said:


> Is the fridge 12 volt, like from an RV/Camper? Or it a normal household fridge?
> 
> Let me guess one more thing..... your friend is using normal car "starting" batteries - - NOT "deep cycle"... am I correct?


Two great questions and probably the answer to what some of the people new to solar don't quite get. Amp hour ratings and current draw of appliances or other things used. By my experience the larger RV/Camper refrigerators when ran on 12 volts or 120 AC supplied by battery/inverter, are not efficient because they generate the heat to run the ammonia absorption cooling process by electrical resistance. About the only time it's viable to use those refrigerators in those modes is when they are charged by the vehicles alternator (Better be a high amp output too) or when they are plugged into grid power. As to batteries, the reality is car batteries and even RV/Marine batteries just don't have the amp hours or the durability of true deep cycle batteries. I've had years of experience in using various types of batteries and the best bang for the buck, as far as I'm concerned is the good old 6 volt golf cart battery. They can be bought at pretty good prices from Sam's Club or from Costco. There are better batteries but you had better brace yourself because prices go up steeply, AGM types can be better than twice the cost of regular golf cart batteries. It all depends on how much one is willing to spend.


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## Viking (Mar 16, 2009)

razorback said:


> Just got this from him:
> 
> My set up will power the thing for about 30 minutes then go off so it can handle the initial load. And after that it shuts off and the batteries still show 12v
> 
> Does that help?


 What is the wattage rating of the inverter? Is the inverter modified sine wave or pure sine wave? A good inverter will have a low voltage cut off, usually just over 10 volts and it could be that shortly after the battery voltage drops to cut off that the battery voltage can rebound to 12 volts. Give us a figure on the physical size and weight of your batteries or if there is an amp hour rating on them. Pictures would also help. Just guessing, but even though the batteries may be deep cycle it sounds like they are too small and don't have enough amp hours even with four in parallel. And by the way it's not a good thing to parallel old and new batteries because the one old battery may draw down the new ones depending on its age and internal condition.


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## NaeKid (Oct 17, 2008)

razorback said:


> Yes it is a normal fridge and I'm asking about the batteries =D


Each part of the system is dependant on the next part in the system.

At the beginning you have solar-panels that are converting the sun's energy into 12-volt DirectCurrent power. Think of those solar-panels as being the faucet in your house filling the sink with water. Think of the sink as being the batteries being filled with power. Add more batteries and they hold more power (water).

Now - when you hook-up the fridge to the batteries, it is kind of like pulling the plug out of the bottom of the sink and leaving the faucet turned on trying to keep it full. At night, there is no sun - no filling the batteries with power - or you could say that you running out of water flowing out of the faucet.

If that fridge is pulling the power out of the batteries faster than the solar panels can put power into them, it is like having a drain on the bottom of the sink larger and faster-flowing than the faucet at the top.

So - now, you will need to add more power-flow to the system so that the panels can stay ahead of the power-drain caused by that fridge - meaning - add more solar-panels. Then - depending on the amount of power being drained out of the system, your friend might need to add more batteries (more sinks if you want to think of them that way).

At some point, the quantity of batteries will be able to supply power to that fridge for a couple of days without needing a recharge by the solar panels - and - your friend will have enough solar panels that the fridge will be able to run on just the panels by themselves for hours at a time.


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## cowboyhermit (Nov 10, 2012)

Viking said:


> A good inverter will have a low voltage cut off, usually just over 10 volts and it could be that shortly after the battery voltage drops to cut off that the battery voltage can rebound to 12 volts.
> 
> This is what it sounds like to me as well, a lot of inverters will indicate a LV condition. A multimeter of any sort will be of huge use for working with this stuff.
> 
> even though the batteries may be deep cycle it sounds like they are too small and don't have enough amp hours even with four in parallel.


Or they might not be charged fully. In the O.P it was mentioned that the batteries were "25 amps" if they are in fact 25 amp *hours* (a normal unit for deep cycle batteries) then they are very small. 4 together would give you 100AH total which is 1 typical large battery.


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## Viking (Mar 16, 2009)

Just to explain differences in inverters, a pure sine wave inverter will have the same wave pattern (perhaps even cleaner) as grid power, the modified sine wave inverter is just a square wave inverter with the edges of the square smoothed so it looks somewhat like pure sine wave. The standard square wave is like the old car radios that were tube type power only they had a vibrator tube that would chop up the 12 volts into plus and minus square wave to run the radios transformer. I haven't experience it but I have read that motors, such as the compressor motor in a refrigerator, may run hotter on square wave or modified square wave inverters. There is also some claim that some electronic systems don't do well with those inverters. My solar systems power pure sine wave inverters. The inverter on our motor home is 2000 watts run by four 6 volt 205 amp hour golf cart batteries hooked series/parallel for 12 volts and 410 amp hours. There are four 100 watt 44 cell mono-crystaline solar panels which feed into a 30 amp MPPT solar controller to charge the batteries. When we were out on the desert boondocking we could make one or two pots of coffee, coffee maker is 1000 watts and after the coffee was made it went into a thermos so as not to run it's hotplate. In the evening we ran a non-LCD 19" TV/DVD for up to 4 hours. The voltage to the inverter never reached cut off voltage. We used some lights both fluorescent and incandescent, for short periods.


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## LincTex (Apr 1, 2011)

razorback said:


> "My set up will power the thing for about 30 minutes then go off so it can handle the initial load. And after that it shuts off and the batteries still show 12v"


If the connections between the inverter and battery are poor, heat will increase in the area where the connection is bad. When that area gets hot, resistance goes up.... and due to resistance, the voltage available to flow to the inverter goes down, causing it to trip off. The batteries now bounce right back up to 12 volts again.

This is a VERY common problem with inverters.

The other cause is an inverter that is just to dang small.


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## Viking (Mar 16, 2009)

cowboyhermit said:


> Or they might not be charged fully. In the O.P it was mentioned that the batteries were "25 amps" if they are in fact 25 amp *hours* (a normal unit for deep cycle batteries) then they are very small. 4 together would give you 100AH total which is 1 typical large battery.


That's the other thing not mentioned either, what is the total wattage of the solar panels? How many solar hours of charge time do they give? And I always like to throw in the fact that the more cells the solar panels have the better chance of having batteries recharged on less than optimal charge conditions, fog, clouds, low winter sun, etc. Then there is the quality issue with solar controllers, MPPT is the best in that it will take the higher voltages from high cell count solar panels and give higher charge rates. There other controllers that are less expensive but I have found the MPPT type to be great for less than favorable sun conditions for good charges. AM Solar has a good tutorial for understanding solar power. www.amsolar.com click on the RV Solar Education. It's about RV solar but it works of home systems as well. If we had to we could pull all of our system off the motor home and use it in our home.


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## Viking (Mar 16, 2009)

LincTex said:


> If the connections between the inverter and battery are poor, heat will increase in the area where the connection is bad. When that area gets hot, resistance goes up.... and due to resistance, the voltage available to flow to the inverter goes down, causing it to trip off. The batteries now bounce right back up to 12 volts again.
> 
> This is a VERY common problem with inverters.
> 
> The other cause is an inverter that is just to dang small.


Consider also the wire size, another area of resistance loss. The wires from the solar panels to the controller, from the controller to the batteries and the big one, the wires from the batteries to the inverter. If any of those wires are too small voltage can be reduced as well. 12 volts DC doesn't hold up well in too small of wire or long distances of those wires.


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## cowboyhermit (Nov 10, 2012)

So razorback, this is really simple, see
In all honesty it really is not that bad though, it is just that there are a few factors with a solar system and without a few solid numbers it is kind of a shot in the dark.

IMO of what has already been said, inverter is shutting down in one of two ways;
1. Essentially flipping the internal "breaker" due to overheating or overcurrent. This is the simplest possibility; inverter is not big enough or is "broken".

2. Inverter is shutting down due to low voltage, this can be due to many factors as have been listed; batteries were not fully charged, batteries are out of capacity, batteries simply are not able to sustain that rate of discharge, wire size or connections are not good, etc.

A multimeter can test the voltage before use on the individual batteries and then when under drain, it can test voltage at the batteries and at the inverter, in short it can narrow down to exactly what the problem is. Ultimately though, without knowing a few numbers (total solar watts, battery size, inverter size) it is impossible for us to say whether the system is actually feasible for that application.

Hope you don't get turned off of alternative energy, it is usually much more straight forward.


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## LincTex (Apr 1, 2011)

cowboyhermit said:


> Hope you don't get turned off of alternative energy, it is usually much more straight forward.


It IS straightforward.... when it is planned out properly and the right components (wire, batteries, panels, inverter, etc) are used.

It sounds like your friend who is trying to run the fridge might very likely have a poorly planned system, or poorly assembled.... and has not yet found where the weakest link is located.


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## razorback (Jul 17, 2012)

Ok guys THANK YOU!!! I have printed off all this and will be faxing it to him to get you all the answers to help him solve the issue. 

Nope not turned off at all, my head might expode but remember I invested in the dummy book so I want to learn. Just have to find a way to wrap my head around it. I love the water and sink though!!!

I have a photo of his batteries let me see if I can figure how to load that from my phone =D

Ya'll are awesome!!!!


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## razorback (Jul 17, 2012)

Got some more info =D

He has used 350 w to 800w inverters, he has four 15watt panels and he said I have battery cables when I mentioned wiring.

Here is the photo he texted me, too.


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## LincTex (Apr 1, 2011)

I think even an 800 watt might be a tiny bit too small...

Lots o' spaghetti in that picture!! I can see using both dual terminals on the battery makes it pretty easy to run cables like he/she did... still can't see how the inverter is wired up. 

If those "alligator clips" on the far right are the inverter connection, then that is the problem!!


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## razorback (Jul 17, 2012)

I'm asking =D


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## NaeKid (Oct 17, 2008)

So - he is running 15x4 watts of power generation (60 watts total) on a system that would probably require a minimum of four-times that much in order to run (240watts) - fudge-factor would say that he needs at least 500watts of power generation in order to keep the batteries topped up - and that is without knowing the rest of the system.

Those clamps (like for booster-cables) are not a good way to connect things together - there is a massive amount of loss-of-power with them. Full circle clamps with soldered connections are the only way to go with that.

I would recommend that if your friend doesn't wanna start over - turn that system into an LED-lighting system for the house or garage (much lower power draw) and re-start with something that has been calculated fully-n-completely for what he wants to accomplish.

Play with an online calculator to try to get a base-line plan going: http://www.wholesalesolar.com/StartHere/OFFGRID/OFFGRIDCalculator.html

*Edit-to-add:* If you use that calculator and run the numbers just for the fridge to run (approx. 60kw/h) their numbers for my area come back with about 500watts of generating power required. Your area might be different.


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## LincTex (Apr 1, 2011)

NaeKid said:


> So - he is running 15x4 watts of power generation (60 watts total)


If those are those cheap junk "Sunforce" panels, then 60 watts is probably a little optimistic


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## Viking (Mar 16, 2009)

LincTex said:


> I think even an 800 watt might be a tiny bit too small...
> 
> Lots o' spaghetti in that picture!! I can see using both dual terminals on the battery makes it pretty easy to run cables like he/she did... still can't see how the inverter is wired up.
> 
> If those "alligator clips" on the far right are the inverter connection, then that is the problem!!


The jumper wires are probably from an auto parts house, bought for convenience of hook-up. The shorter the jumpers are the less the resistance loss. I'm with LincTex on that inverter, companies that sell inverters and generators are getting better about rating them for continuous and peak (very short term power as in getting motors up to speed). My 2000 watt inverter has a peak of 4000 watts for 5 seconds. One factor in designing solar that hasn't been mentioned here is the current draw of the inverter in no load and full load. If battery systems are sized too small just the current draw from just having the inverter connected can bring their voltage down. Undersized solar charging system may not keep up with just a small discharge like that. There is plenty of info on solar on the internet, I've done tons of research myself, there are formulas for sizing that are very helpful. Thing is, don't just have the bare minimum or you'll end up with problems like you have mentioned. A good solar system has to have a good reserve to it as there are factors that will tax even the best systems, such as cloudy days, fog, dust, late fall thru early spring low sun angle and hot days where are fridge will run longer and more frequent. That's why I like a 44 cell 100 watt panel over a 32 or 36 cell panel for charging a 12 volt system, even on a poor sun day I can still get batteries charged. The 44 cell panel can produce 21 volts under load the 32/36 cell panel puts out 17-18 volt range and those figures are best case situation, new panels, clear skies, premium temp for operation and panel angled to the sun. Thing is, life is not perfect and I would say that four 15 watt panels are insufficient to charge the batteries for the discharge rate they are getting.


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## BillM (Dec 29, 2010)

*Starting amp draw*

The compressor in a refrigerator will typically pull 180 % of the full load amp rating for a second during start up.

When you put your volt /ohm meter on the compressor terminals and start up the refrigerator, if the voltage drops when it starts , you do not have enough volt / amp capacity .

A 20% redundancy is the usual engineering allowance to provide for adequate power.

You should never pull more than eighty percent of the total amps of the service.


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## razorback (Jul 17, 2012)

Update:

Got a text last night that stated he now has a 3000 watt inverter and his fridge has been running for 3 hours =)

That you for all the help!!! Just wait till I start my adventure to solar power!!!


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