2000k system only puts out 500 watt why?

[charles2,david000k]

24V requires thinner gauge wire for the wiring runs, which means it will be cheaper. However there are more devices available for 12V. Use fuses/breakers based on the smallest wire gauge in the run, the temperature rating of the wire and how many conductors you are running together.

Won't work.

Sure, but you will need something called an LCB (linear current booster) to allow the pump to start reliably. They are about $150.

What gauge would I run for a 12V supply about 70ft max. I just want to run lights off this but the home is 40ft long so I figure 70ft gives me room for obstickal I might have to work around from power source to fuse box.

[charles2,david000k]

You are not going to run a steam engine with a heating loop. You would need a full blown boiler matched
to the engine. I'd suggest looking into a much simpler Peltier Junction which is lower efficiency, but has
no moving parts. Any cracked panel, I'd expect to die a slow death as moisture seeps in. Bruce Roe

I don't know my stove gets pretty hot it set up to work a lot like a rocket stove and my heating loop is in the mouth of the flue pipe I melt lead and aluminum in it some times and when I first started out with the heating loop I started with a water grade copper which worked out fine until the water ran out then the pipe started to warp and melt copper melts somewhere around 1,900 F. It's a shame about this broken panel I sealed it up with silicon while in the house and got the humidity down as low as I could I think it was around 40% that day and the brakes are very small. really small 3 of them about the size of a pencil eraser and did not come through the front of the glass just the white backing and cracked the cells themself but like I said I sealed them up with silicon. What do you think the life span could be if you had to put a number on it?

It is looking like I will be getting some reading today off of panel number 3 it's been raining the past two or three day and had some clouds this morning but we are clear and blue now but when I set up I got 35V off all 7 panels. so we are looking better and better every day.

[jflorey2]

1. I want to run DC back up lights in my home to all the rooms. What is the safest and most cost effective way to go 12V or 24V and what Awg wire and lights should I use?

24V requires thinner gauge wire for the wiring runs, which means it will be cheaper. However there are more devices available for 12V. Use fuses/breakers based on the smallest wire gauge in the run, the temperature rating of the wire and how many conductors you are running together.

2. I burn wood all winter here because it's free we have a major wood betel problem in our area and we constantly get people to ask us to come in and cut these trees down in the winter to try and control the wood betel population. So I want to put a heating loop in my wood stove and produce steam and wanted to run a small steam engine off that loop to produce DC current to charge the bank but steam engines are a dead thing now day. Does anyone know where I could pick up a small one to run a PMA?

Won't work.

3. I have a 24 volt panel that only puts off 24.4V and 8 amp can I directly run a 12V water pump off it with no batteries?

Sure, but you will need something called an LCB (linear current booster) to allow the pump to start reliably. They are about $150.

[bcroe]

I want to put a heating loop in my wood stove and produce steam and wanted to run a small steam engine off that loop to produce DC current to charge the bank but steam engines are a dead thing now day. Does anyone know where I could pick up a small one to run a PMA?

3. I have a 24 volt panel that only puts off 24.4V and 8 amp can I directly run a 12V water pump off it with no batteries? This is the panel the distributor had me cut the back off the junction box off and replaced the diodes then was further damaged in shipping. It was putting out 29V before the diodes were replaced then dropped to 26V after that then the panel was cracked and it dropped again to 24.4 to 24.7. I just need the pump to fill water tanks as needed.

You are not going to run a steam engine with a heating loop. You would need a full blown boiler matched
to the engine. I'd suggest looking into a much simpler Peltier Junction which is lower efficiency, but has
no moving parts. Any cracked panel, I'd expect to die a slow death as moisture seeps in. Bruce Roe

[charles2,david000k]

Just want to let you guys know I have not forgotten about you and will do a update on the next panel on the next good day. But I did have a few question a little off topic I been meaning to ask.

1. I want to run DC back up lights in my home to all the rooms. What is the safest and most cost effective way to go 12V or 24V and what Awg wire and lights should I use?

2. I burn wood all winter here because it's free we have a major wood betel problem in our area and we constantly get people to ask us to come in and cut these trees down in the winter to try and control the wood betel population. So I want to put a heating loop in my wood stove and produce steam and wanted to run a small steam engine off that loop to produce DC current to charge the bank but steam engines are a dead thing now day. Does anyone know where I could pick up a small one to run a PMA?

3. I have a 24 volt panel that only puts off 24.4V and 8 amp can I directly run a 12V water pump off it with no batteries? This is the panel the distributor had me cut the back off the junction box off and replaced the diodes then was further damaged in shipping. It was putting out 29V before the diodes were replaced then dropped to 26V after that then the panel was cracked and it dropped again to 24.4 to 24.7. I just need the pump to fill water tanks as needed. I think the pump is rated 12V at 6 or 7 amps it's a sureflow pump I pulled out of a motorhome.

[inetdog]

No it's a 250 watt panel putting out maybe 208W and we cut out most if not all the other factors by only testing just the panel only when we do current or amp's and on perfect condition day I won't even set up to test if there is a chance of light clouds it has to be a perfectly clear day before I waste my time setting up. That is probably why some readings were off today. An I got to be pulling over 250 watt because my inverter puts out 6000 watts easy and sucked the bank completely dry and burnt out my second to last 250 amp fuse in the process but the fuse burn up because they are rated at 32V and the panels should peak at 38V and 8 amps I have solenoid cc and MPPT built in to the inverter I even open the inverter up to blow out dust and check it has huge coils and a mess load of the flat diode I have seen in other MPPT cc and for $2000 it better really be MPPT. I will have to do a update when I get more time this thread is getting long.

What will happen is that if the inverter is designed to put out 1200W from a 12V battery and you put that load on it the current into the DC input of the inverter will be something upward of 100A. (More if the efficiency of the inverter is low.) But that does not mean that you should use a 100A fuse on the input (or on the battery). When the battery voltage drops under load and at the low end of charge down to 10v the inverter will be drawing 120A to get the same 1200W input power.
And if you have a load which has a startup surge, such as a motor or an incandescent lamp the current into the inverter can be as much as twice that (240A) for a few seconds.
A 100A fuse can handle 120A indefinitely as long as the fuse holder and connections are good. Above 130A it will blow in anywhere up to three or four minutes, to close to instant on a really high overload.
For a fuse on the DC circuit from the panels to the CC, there is a chance that the CC will draw up to Isc of the panels under some fault conditions rather than just Imp.
If the fuse holder terminals do not make good contact with the fuse or if you have a loose wire connection to the fuse holder that will increase the temperature of the fuse and cause it to blow at less than the rated current.

Typical aftermarket automotive fuse holders are often not good for that current level on a continuous basis. And whatever the reason, when the fuse finally blows the high voltage will cause an arc which will keep current flowing and dissipate hundreds of watts in the fuse and holder, potentially destroying the whole thing and catching on fire. Given a 32V DC fuse rating and a 38V Vmp you will have a real problem. And if the panel Vmp is 38, the panel Voc which is what will be trying to keep the arc going, could be as much as 46V.

[jflorey2]

Solar panel companies really should label their panels better. Like something that says a 250W really only puts out 200W.

No, they really put out 250 watts under STC (standard temperatures and conditions.) That means 25C and 1000 watts per square meter. And that might happen in say Canada during spring where it rained the day before, it is now severe clear, the temperature is 5C and the wind is blowing. The Sun warms the panels to 25C and you actually get their rated power. Having STC always mean the same thing is very important because you can accurately compare panel A to panel B to see which gives you more power.

But in summer your panels are going to be closer to 50C (they get hot in the sun) the sky won't always be perfectly clear and your panels will get dirty over time. Plus, of course, off-axis operation will reduce your total power. Which is why 210W from a 250W is more likely in "real world" conditions.

(BTW if you don't like STC there is a measurement called PTC which is much more indicative of real world conditions.)

then one day in the middle of summer on the hottest day the system went nuts burning wires, disconnect, cc, battery bank and fuse up everything between the panels to the fuse right before the inverter was trash like there was a huge power spike or someone crossed the wires.

That has nothing to do with how those panels are rated. That is simply a poorly designed system.

I still have not found out if a 1000 HID lamp would work for testing?

No. Let's say you do that and you get 9 watts out of your 250 watt panel when it's under the HID lamp. Then you move the light around and tilt the panel differently and it gives you 10 watts. What does that tell you? Nothing really.

And the new solenoid cc the guy gave me is acting up it is hot right now at 8:30 at night no sun and the inverter is off so the only power going to it is from the battery bank and I thought it was stuck in the off position again but I checked and it's not. for some reason when it is off the solenoid gets super hot which is probably what caused the last one to burn up.

Get a real charge controller. This solenoid design is going to cost you a lot in the long run.

[LETitROLL]

I am still wondering how to go about buying used batteries. As far as pricing goes I stopped by my local scrap yard trying to buy a few but they refused to sell me any due to lead is toxic and acid is dangerous. So what I decided to do is put up flyers offering to pay other for scrap car and truck batteries for 0.14 cents a pound it is a little more than what local scrap yard is giving but I have no way to weigh a battery. So I was wondering if I could use group size to determine weigh so I am not ripping people off or me?

Solar panel companies really should label their panels better. Like something that says a 250W really only puts out 200W. See this is what made me so mad I got these panel and tested them and they put out exactly what they were marked on the back label 38.1 volts and 8.6 amps with no special treatment and it was a cloudy day they even read on the charge controller of 38 volts when the cc was not charging and pulled down to 36 volts with a 6,000 watt inverter pulling on them feeding my whole home that's with a electric stove, a 2 horse well pump, 4,500watt water heater, and everything else a 1,200 sq house has lights tv fridge deep freezer etcetera and it did that with no problem I was happy then one day in the middle of summer on the hottest day the system went nuts burning wires, disconnect, cc, battery bank and fuse up everything between the panels to the fuse right before the inverter was trash like there was a huge power spike or someone crossed the wires. Nominal peak power(Pmax) 250w with a fall off of 10% in the first 15 years is 225 watts at the end of 15 years it should be no lower than 225 watt for peak output and this is how the warranty reads this is why I am mad about the whole thing solar manufacturers should really think of rewrite their warranties if this is the true capability of their panel. I know it probably sounds like I am mad at you but I'm not it is just frustrating to think that a panel fell off 25 watts in the first I test the other panel I have had in the house today and it's at 24.4 volts by itself with no load. but when I did my loop test it put out over 9 amps. I still have not found out if a 1000 HID lamp would work for testing? And the new solenoid cc the guy gave me is acting up it is hot right now at 8:30 at night no sun and the inverter is off so the only power going to it is from the battery bank and I thought it was stuck in the off position again but I checked and it's not. for some reason when it is off the solenoid gets super hot which is probably what caused the last one to burn up. IDK sorry I got of on a rant I hope you all are well with all this isis junk going on and remember to be safe.

Sounds like your flyers might be a good idea for getting used batteries, you should be able to get average weights for various sizes off of manufacturers sites on the internet.

[charles2,david000k]

For middle of November in North America that does not seem bad, no matter how big and bright the sun is, in most of North America right now it is at a "Poor Angle" and the atmosphere is eating part of your energy. Also if I remember correctly your panels are fixed mount, so even during mid-day sun when things look good to the naked eye, if the elevation of your panel(s) is not perfectly square to the sun (which is almost impossible with fixed mount) it makes it impossible to match the lab conditions that your panels nameplate wattage was created with.

I am still wondering how to go about buying used batteries. As far as pricing goes I stopped by my local scrap yard trying to buy a few but they refused to sell me any due to lead is toxic and acid is dangerous. So what I decided to do is put up flyers offering to pay other for scrap car and truck batteries for 0.14 cents a pound it is a little more than what local scrap yard is giving but I have no way to weigh a battery. So I was wondering if I could use group size to determine weigh so I am not ripping people off or me?

Solar panel companies really should label their panels better. Like something that says a 250W really only puts out 200W. See this is what made me so mad I got these panel and tested them and they put out exactly what they were marked on the back label 38.1 volts and 8.6 amps with no special treatment and it was a cloudy day they even read on the charge controller of 38 volts when the cc was not charging and pulled down to 36 volts with a 6,000 watt inverter pulling on them feeding my whole home that's with a electric stove, a 2 horse well pump, 4,500watt water heater, and everything else a 1,200 sq house has lights tv fridge deep freezer etcetera and it did that with no problem I was happy then one day in the middle of summer on the hottest day the system went nuts burning wires, disconnect, cc, battery bank and fuse up everything between the panels to the fuse right before the inverter was trash like there was a huge power spike or someone crossed the wires. Nominal peak power(Pmax) 250w with a fall off of 10% in the first 15 years is 225 watts at the end of 15 years it should be no lower than 225 watt for peak output and this is how the warranty reads this is why I am mad about the whole thing solar manufacturers should really think of rewrite their warranties if this is the true capability of their panel. I know it probably sounds like I am mad at you but I'm not it is just frustrating to think that a panel fell off 25 watts in the first I test the other panel I have had in the house today and it's at 24.4 volts by itself with no load. but when I did my loop test it put out over 9 amps. I still have not found out if a 1000 HID lamp would work for testing? And the new solenoid cc the guy gave me is acting up it is hot right now at 8:30 at night no sun and the inverter is off so the only power going to it is from the battery bank and I thought it was stuck in the off position again but I checked and it's not. for some reason when it is off the solenoid gets super hot which is probably what caused the last one to burn up. IDK sorry I got of on a rant I hope you all are well with all this isis junk going on and remember to be safe.

[LETitROLL]

No it's a 250 watt panel putting out maybe 208W

For middle of November in North America that does not seem bad, no matter how big and bright the sun is, in most of North America right now it is at a "Poor Angle" and the atmosphere is eating part of your energy. Also if I remember correctly your panels are fixed mount, so even during mid-day sun when things look good to the naked eye, if the elevation of your panel(s) is not perfectly square to the sun (which is almost impossible with fixed mount) it makes it impossible to match the lab conditions that your panels nameplate wattage was created with.

[jflorey2]

No it's a 250 watt panel putting out maybe 208W

Sounds about right. You almost never get rated power out of a panel. If you are getting 208 watts calculated out of a 250 watt panel it is doing its job - especially with a simple solenoid based charge controller.

and burnt out my second to last 250 amp fuse in the process but the fuse burn up because they are rated at 32V and the panels should peak at 38V and 8 amps

Voltage does not burn out fuses. Current does. (However, once you blow the fuse, then the voltage rating becomes VERY important - and you'll see fireworks if you use a low voltage fuse on a high voltage system.)

I have solenoid cc and MPPT built in to the inverter

Inverters don't do MPPT charge control. That only happens in the charger (the thing between the panels and the battery.) A standard inverter does not have an MPPT, nor does a solenoid based charge controller.

I even open the inverter up to blow out dust and check it has huge coils and a mess load of the flat diode I have seen in other MPPT cc and for $2000 it better really be MPPT.

Surely you are not thinking that your inverter has any given functionality simply because it has "flat" components in it?

[jflorey2]

1) "You test Isc and Voc" This is of course the easiest and most common way to test a panel and see if it is close to spec or not, but aren't they usually (or always) measured one at a time?

Yes. The easiest way is get a meter that is rated for more current than the panel is capable of, then test Voc with the meter set to volts and Isc with the meter set to current. (Two separate tests, generally with two different connections on the meter.)

To my way of thinking it is not mathmatically possible for any panel to put out anywhere near Voc when it is being tested to Isc (short circuit).

Right. The definition of "short circuit" is zero voltage across the device, just as "open circuit" refers to a zero current condition.

Since they are readings, that by nature cannot exist at the same time, I am trying to make sure i understand the value of multiplying the two together, and/or if it is a common practice in the solar industry to actually multiply those two together, or just know what they are individually.

If you multiply the two together you get an artificially high power - because the voltage will be lower under a heavier load, and the current will be lower under a lighter load. Fortunately the relationship between Voc and Vmpp, and Isc and Impp, is fairly well known (and shown explicitly on the panel's data sheet.) If you don't have access to the data sheet, and it's a monocrystalline panel, you'll get about 70-75% of the product of Voc and Isc at the maximum power point.

[charles2,david000k]

Let me see if I get this . Your panel outputs 200w+ and is 240w rated right? And you are not happy?
I think you're wasting your time with testing the panels . Those panels are performing as they should but your weak points are elsewhere in the system . It could be wire , contacts or the most important pice in the system for harvest CHARGE CONTROLER.
The panel will produce and if the system components are up to scratch to handle the power and efficiently harvest it when available.
Panel will only produce what the system can take even if the panel has a higher rating .Only a efficient system will be able the harvest it all.

No it's a 250 watt panel putting out maybe 208W and we cut out most if not all the other factors by only testing just the panel only when we do current or amp's and on perfect condition day I won't even set up to test if there is a chance of light clouds it has to be a perfectly clear day before I waste my time setting up. That is probably why some readings were off today. An I got to be pulling over 250 watt because my inverter puts out 6000 watts easy and sucked the bank completely dry and burnt out my second to last 250 amp fuse in the process but the fuse burn up because they are rated at 32V and the panels should peak at 38V and 8 amps I have solenoid cc and MPPT built in to the inverter I even open the inverter up to blow out dust and check it has huge coils and a mess load of the flat diode I have seen in other MPPT cc and for $2000 it better really be MPPT. I will have to do a update when I get more time this thread is getting long.

[Raul]

Let me see if I get this . Your panel outputs 200w+ and is 240w rated right? And you are not happy?
I think you're wasting your time with testing the panels . Those panels are performing as they should but your weak points are elsewhere in the system . It could be wire , contacts or the most important pice in the system for harvest CHARGE CONTROLER.
The panel will produce and if the system components are up to scratch to handle the power and efficiently harvest it when available.
Panel will only produce what the system can take even if the panel has a higher rating .Only a efficient system will be able the harvest it all.

[charles2,david000k]

I don't know where you are located, but from some things you've mentioned I'm guessing near Knoxville.

Using PVWatts, for the tilt (say, 25 deg) and direction (south) you've described, mid-day plane of array irradiance might be around 830 W/m2.

The Isc of 8.62 was taken under standard test conditions of 1000 W/m2. (830/1000) * 8.62 = 7.2 A, so the readings you are getting are in the right ballpark. Yes, moving on to the other panels and verifying the Voc and Isc for each would be a good next step. If they all read about the same, then you can be more confident performing a load test.

I'm not sure where you are coming up with the 180 W value. During an Isc test, the panel voltage should be approaching zero, so you won't get measurable power like that. For example, at 7.2 A, you would need 25 V to get to 180 W power (7.2 * 25 A = 180). I guess 180 W would be about right for power for a load test on this panel, if you hooked it up to your (discharged) 24 V battery. Is that what you did?

The 180w was a load test which is what I did today the meter I have track and logs data throughout the whole day from the time you hook it up to the time power output stops. Like today I hooked into panel number two and got these results.

test started at 12:35pm to sundown at 4:55pm skies were clear and I did not get a temp for today but it seemed like it was pretty cool 55F I would have to say.

Ap 7.45
Ah 5.031
Wp 204.8
Wh 150.2
Vm 00.00

I think the Vm was changed due to I now have a backup power source to run the meter. From the readings I got today my peak watts were 204.8 my location is above Spring city Tn in a place called luminary or Bledsoe county but I live almost at the top of the mountain I can see watts bar nuclear power plant and the smokie mountains on a really nice day. you can find me here

https://www.google.com/maps/@35.7104717,-85.001619,98m/data=!3m1!1e3

But I am not really happy with the readings I got as of today so I will be running this same test again on the next good day