Cheap and dirty offgrid farmer

[Offgridreefer]

6 years ago I moved off grid when I purchased 26 acres without any power on it. I've been slowly building my solar system up as I can afford. Just hoping I can jump ahead of that learning curve a little bit if I can network with a few of you guys who have been there and done that already.

 

[snoobler]

You found a good place for that.

 

[Offgridreefer]

Since I've already posted here I'll just go into my current issue which is my main reason for coming to this forum. If I'd be better off posting this issue in another area please just point me in the right direction.

This summer I upgraded my solar system significantly. I purchased 8 windynation 100 watt panels, a renogy rover 60 amp mppt and I have those charging a 1200 amp hour battery bank wired in parallel for a 12 volt system. The maximum charging power I have ever seen from this system is 550 watts. That's the reading that the mppt gives, usually it's around 430-450. This is under ideal conditions. Full sun, directly over head. I have the panels wired up in sets of 4 in series, then the 2 sets of 4 wired in parallel into the mppt. The open circuit voltage of each set of 4 panels is is about what it should be for their manufactured rating. About 85 volts if I remember correctly. The short circuit amps of each group of 4 is also within a reasonable range of the manufactured rating. Around 5.5 amps I think. It's been a couple of months since I took all these readings and I can't take new readings right mow because forest fires have obstructed the sun. Since the panels appear to be functioning reasonably close to their rated capacity I assumed it was the mppt. What I have discovered is that renogy has horrible customer service and really have been of no help.

Can anyone shed any light on this? Any more information I can provide to help get this figured out? Are windynation panels garbage? Is it unreasonable to expect them to provide close to their rated output? Is it more likely the mppt? Are renogy products as terrible as their customer service?

Thanks for any help you can provide!

 

[GLC]

Yep, list what your hopes and dreams are. Lot of knowledgeable people here.

 

[GLC]

What were your amps and volts shown on the controller? Size and length of wire from the panels?

 

[Offgridreefer]

Here is a typical reading from the mppt at mid day full sun. Each set of 4 panels is run through about 40' of 12 awg cable. The open circuit voltage and short circuit amp readings I gave were at the mppt end of the cables not straight out of the panels, so voltage drop shouldn't be the issue I don't think. Yes, the battery status is 100%, but the mppt is still in charge mode and If I turn on a 500 watt load when it's at this state the charging input doesn't change and the %charged consistently drops.

 

[nwillitts]

6 years ago I moved off grid when I purchased 26 acres without any power on it. I've been slowly building my solar system up as I can afford. Just hoping I can jump ahead of that learning curve a little bit if I can network with a few of you guys who have been there and done that already.

where do you live?
500 watt load from an inverter?
any pics of your set up?

 

[Offgridreefer]

where do you live?
500 watt load from an inverter?
any pics of your set up?

I live in western oregon. Yes, 500 watt air conditioner run off of a renogy 1000 watt sine wave inverter. I can post some pics later. Anything specific I should be sure to get pics of that could be helpful?

 

[GLC]

First remember, open circuit voltage can be the same for using 14 or even 16 gauge wire. It has no load nor is pulling any amps. Just because you are reading 85 volts, it does not mean you are not losing any amps. By the photo of the controller at that time you are pushing 10 amps with 12 gauge wire at 40 feet x 2 = 80 feet because of your positive and negative distance total. I would check a wire calculator chart but you my be light on the wire.

 

[GLC]

Next, what batteries do you have? Is your controller set up on the type of batteries that you have? Depending on your settings, you may be going to float too quickly? Also bear in mind, in this heat you may be only able to get 70 to 80 percent of your panel rated watts.

 

[Offgridreefer]

First remember, open circuit voltage can be the same for using 14 or even 16 gauge wire. It has no load nor is pulling any amps. Just because you are reading 85 volts, it does not mean you are not losing any amps. By the photo of the controller at that time you are pushing 10 amps with 12 gauge wire at 40 feet x 2 = 80 feet because of your positive and negative distance total. I would check a wire calculator chart but you my be light on the wire.

According to the manufacturer the maximum power current is 5.58 amps. That shouldn't be excessive for 12 guage wire should it? Ill work on finding a wire calculator and get back to you.

 

[GLC]

5.58 amps per panel correct? But you have them in parallel and series. Multiply the panels that you have in parallel times your amps, that would be your max amps total. Just by your photo of the controller at that point, 464 watts at 64.4 volts equal 7.20 amps. If the same reading was made at 800 watts, volts may be closer to 14 to 15 amps. Now think about the size of your wire.

 

[Offgridreefer]

5.58 amps panel correct? But you have them in parallel and series. Multiply the panels that you have in parallel, that would be your max amps. Just by your photo of the controller at that point, 464 watts at 64.4 volts equal 7.20 amps. If the same reading was made at 800 watts, volts may be closer to 14 to 15 amps. Now think about the size of your wire.

I didn't properly explain how I have my panels wired. I have 8 panels. Manufacturers rating for each panel is; max power voltage =17.95 volts and max power current =5.58 amps. I have 4 panels wired in series, 71.8 volts and 5.58 amps, with their own 12 guage wire run all the way to the mppt. Then another set of 4 wired in series with their own 12 guage wire run all the way to the mppt.
Yes, I agree with you, 464/64.4=7.2 amps, but the wires going from the paneks to the mppt are not having to take 7.2 amps because the maximum amps that the panels can produce is 5.58. Correct? Am I missing something?

According to the voltage drop calculator on calculator.net the voltage drop for 71.8 volts and 5.58 amps over 40 feet of 12 guage wire is .71. That's totally acceptable and definitely does not account for the low charging watts.

 

[Offgridreefer]

Next, what batteries do you have? Is your controller set up on the type of batteries that you have? Depending on your settings, you may be going to float too quickly? Also bear in mind, in this heat you may be only able to get 70 to 80 percent of your panel rated watts.

I have flooded lead acid deep cycle batteries. It doesn't go to float until the batteries reach 14.5 volts. I don't think that's too quickly. Plus, that's definitely not the issue since it typically shows a solar output of 450 watts long before it goes into float mode. Even when the batteries are inder 50% charged, it still shows around 450 watts. The only time I've gotten a reading over 500 watts was when I climbed on the roof and poured cold water on all the panels, then it got to almost 550.

 

[GLC]

Ok,got it, i did not realize that you had seperate wiring from each series of panels.

 

[John Frum]

I have 4 panels wired in series, 71.8 volts and 5.58 amps, with their own 12 guage wire run all the way to the mppt.

You have 2 strings of 5.58 amps@71.8 volts.
That is 11.16 amps@71.8 volts.
How long is the round trip circuit?

 

[Offgridreefer]

You have 2 strings of 5.58 amps@71.8 volts.
That is 11.16 amps@71.8 volts.
How long is the round trip circuit?

Maximum round trip circuit is 80'. But that's longer than it actually is. It's more likely closer to 60. I'm just estimating high because I can't get to my system to get exact measurements at the moment. Keep in mind that each 5.58 amp array is on it's own wire all the way to the mppt. So no 12 guage wire is ever having to handle 11.16 amps, only 5.58.

 

[GLC]

I started out with 3 , 305 watt panels on the house in series. 120 volts at 8 amps. Should have got over 900 watts at full 90 degree of sun on the panels. I was barely getting a little over 600 watts max. I added a 4th panel in series and it pushed the unit over 150 volts which the controller did not like and shut down. I changed things up and went 2P2S which should have given me over 1200 watts but i have only gotten max 900. Just because i was supposed to be getting 1200 on paper it did not mean that i would get 1200 phyically. Just food for thought as far as panel out put.

 

[Offgridreefer]

I started out with 3 , 305 watt panels on the house in series. 120 volts at 8 amps. Should have got over 900 watts at full 90 degree of panels. I was barely getting a little over 600 watts max. I added a 4th panel in series and it pushed the unit over 150 volts which the controller did not like and shut down. I changed things up and went 2P2S which should have given me over 1200 watts but i have only gotten max 900. Just because i was supposed to be getting 1200 on paper it did not mean that i would get 1200 phyically. Just food for thought as far as panel out put.

I've considered that possibility, and that's why I'm here asking about this. I don't expect 100% of the rated output, but 56% seems pretty far below the manufacturers rating. Even your system, theoretically 1200 watts, giving 900, thats still 75%. 75% of my 800 watt system would be 600 watts. Ive never seen that.

 

[Offgridreefer]

If it's common and expected to get 50-75% of the rated power out of panels under optimal conditions then I'll quit trying to figure out whats going wrong and simply add more panels. That doesn't seem right to me though.