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Discussion Starter · #1 ·
I recently installed a new bimodal solar system (grid tie, and non grid tie with battery backup). I have 33 X 230 watt solar panels. For a total system of 7.5 Kwatts. The problem is that I'm not generating the power I expected.

In a weeks time (of relatively good weather, two mornings of rain ,and one afternoon of broken skies) I have only broken 5.0 of kwatts produced twice (once I hit 5.07 and once I hit 5.17 kwatts). On each of these times, this was the amount of power INTO the inverter. The amount out of the inverter (for my use) both times was only 4.4 kwatts!

For the amount of money I spent I'm very upset. I expected much more!

I have an Outback flex 500 dual inverter (supposedly top of the line), that seems more efficient at producing noise (fan) and heat (87 degrees inside the inverter room) than electricity.

I have two basic issues. One. Is the efficiency from the panels to the inverter acceptable for a peak sun time (from 7.5 down to 5.17 or an efficiency of 68%)? Second is the further loss of power thru the inverter (from 5.17 to 4.4, or the loss of another 15%) from the inverter acceptable?

Is this in the range of possibilities or did they screw something up in the installation?

Going from 7.5 potential to 4.4 actual does not make me a happy man! I need a second opinion, or at least have some ammunition to fire with, before I go ballistic with the contractor.

Regards,
Icarus
 

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as a prepper you should have plenty of ammo....... but I think you mean for a discussion..... how long are the feeds from the panels to the inverter...... what size cable did they use.........both can lead to signifcant line loss if sized to small..........
 

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Doesn't sound right. What size wire did the run? Most importantly, hows your exposure? Where are you located, up north doesn't get the same intensity as down south. I would use a multi meter and go through all 33 panels and get a voltage/amp reading for each on a full sun day. If your sun and wire is good, you might have a couple dead or weak panels. Let us know.
 

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Live Secret, Live Happy
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I have been running a small solar system for 16 yrs.

First where do you live and what does the nearest DOE solar incidence recording station say. Are you even in a decent area for solar? What's the typical sun hours and intensity?

I test each panel while mounted for max voltage, max current, and voltage against a common load.

Then I install test points and current shunts in the feed lines from the panels to the controller.

I want to see less than a 1/2 volt drop in my feed lines. I went with 4/0 cable (over kill) to achieve that.

The final leg is the connections out of the battery to the inverter. I use copper buss bars.

From the inverter to the load I use normal 12 ga extention cords.
 

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I used 10ga from my panel to regulator. Same to the batteries. 4ga to the inverter with soldered on copper eyes. I have an average of .3v difference between battery and regulator. Seems the big wire is key in preventing bleed off. DC current does that over distance. Plus its like pouring too much water through a small hose you know.
 

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Hard to say if you are getting the maximum possible out of the inverter. Since you are running a dual battery and grid tie setup there may be losses involved with the manner of apportioning load. This kind of setup is a bit unusual to me. Most grid tie setups do not make use of storage batteries, they simply meter to the grid. They also tend to be at much higher voltages from the panels than is usable for charging. That would mean a battery charger is in the setup.

As to the amount you are getting from the panels, hard to know if they are setup at the proper angle to receive the maximum benefit from the sun. You would be lucky to achieve their max rating however.
 

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Discussion Starter · #7 ·
Thanks for the inputs.

Feed from the panels to the inverter is about 40 feet.

I live in the Atlanta Area. 5.5 hrs of sunlight average per day. (It's been higher than that over the last week, however it has been humid......that mean's bright but hazy).

It's a 48 volt system with wires 3/4 of an inch thick. I'll get the specifics on the wiring from the contractor tomorrow.

Hick. How do you access the DOE solar incidence recording stations?

As for the ammo....... statistically I'll be dead before I use it all up.
 

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I didn't catch the mentioned "grid tie", that makes sense. I'm guessing it running off what excess you have.......darn I'd like to hop all over this set up with a meter!
 

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Couple of questions regarding the PV panels...Are they locked in at one angle...or are they tracking the sun?? If locked in at one angle you will not be getting as much sunlight as a set that is tracking the sun...(about 25 to 40 % more if tracking) Anything at all that might be blocking some of the sun to any of the solar panels (I.E. - trees, another building or structure)
 

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Discussion Starter · #12 ·
Couple of questions regarding the PV panels...Are they locked in at one angle...or are they tracking the sun?? If locked in at one angle you will not be getting as much sunlight as a set that is tracking the sun...(about 25 to 40 % more if tracking) Anything at all that might be blocking some of the sun to any of the solar panels (I.E. - trees, another building or structure)
Fixed roof panels. Latitude of 32 degrees. The current angle of the panels is41 degrees from the horizontal. Not optimum I know. Optimum year round is 34 degrees from horizontal. Optimum for July is 18 degrees.

No shade with one exception. Shade blocks three panels early in the morning until 8 am. We are not generating much power then anyway.

Regards,
Icarus
 

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Live Secret, Live Happy
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Thanks for the inputs.

Feed from the panels to the inverter is about 40 feet.

I live in the Atlanta Area. 5.5 hrs of sunlight average per day. (It's been higher than that over the last week, however it has been humid......that mean's bright but hazy).

It's a 48 volt system with wires 3/4 of an inch thick. I'll get the specifics on the wiring from the contractor tomorrow.

Hick. How do you access the DOE solar incidence recording stations?

As for the ammo....... statistically I'll be dead before I use it all up.
Here is doe web site, http://www.nrel.gov/gis/solar.html

But they have changed it a great deal. I'll have to look for the specific city data.
 

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Fixed panels = max power ? No way. You MIGHT get to the max rated output under these circumstances. Snow on the ground, roof and everything around you. Bright sun, 2 pm, with the sun directly aimed at your panels.

Also, what type of solar panels are you using. Some are much better then all the rest. But never have seen any that put out the max.
Also, me thinks your losing some of your incoming power in the 40' distance just to your inverter.
 

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Depends on where you live.

I remember reading about one company in Seattle with a 10kW install who produced only an average of 13 kWh/day (ouch!)
 

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Icarus:

Thanks for the inputs.

Feed from the panels to the inverter is about 40 feet.

I live in the Atlanta Area. 5.5 hrs of sunlight average per day. (It's been higher than that over the last week, however it has been humid......that mean's bright but hazy).

It's a 48 volt system with wires 3/4 of an inch thick. I'll get the specifics on the wiring from the contractor tomorrow.

Hick. How do you access the DOE solar incidence recording stations?

As for the ammo....... statistically I'll be dead before I use it all up.
since we are in the same area, do your panels have these angles to the sun??
Latitude and seasonal corrections for Atlanta
33° 44' 56" N / 84° 23' 17" W
Latitude +15 degrees in Winter, set in mid October or 48.44 degrees
-15 degrees in Summer, set in Mid March or 18.44 degrees?????

Laus Deo
overbore
 

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Go through and in full sun, check YOURSELF the voltage output of each panel individually, i.e, disconnect the wiring and check each panel's output.

That would be the FIRST place I'd start.

Years ago I noticed our array wasn't putting out what it should. You just kinda learn to feel these things when you've lived off an AE system for a while.

Sure enough, pulling each panel I found three of 14 Kyocera 120's that were only producing 9 volts in full sun! A call to Kyocera provided me with 14 NEW Kyocera 130 watt panels. Even though only three were malfunctioning and they were already 7-8 years old, Kyocera replaced the ENTIRE ARRAY. And since they had discontinued the 120 watt panels, I got 130 for an extra 140 watts total!

Might have been Joey the new guy wired some of your panels. I've seen standard house/industrial type electricians literally with their knickers in a twist when it comes to working with DC and solar. In the same token, I can wire up a battery bank, inverter, MPPT's, etc. but couldn't wire a house with 110!! :eek:

Anywhoo, check EACH panel in full sun. When you have problems like this you have to rule things out in a logical order, otherwise you'll waste a lot of time guessing -BTDT with 12 years producing our own power.

Good luck, let us know how it works out!
Lowdown3
 

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as someone who is planning on getting off grid on solar, but starting small and building it up over time...this thread is very informative for me.

I was kinda surprised to hear that 10ga wire is sufficient for the run from the panels to the charge controller...guess I thought you'd have to run bigger or suffer lots of loss
 

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Yeah, I wanted to get in on this thread as well with a subscription. I'm always looking to tweak my system. Been thinking about adding on - this gives me some more ideas. Thanks :)
 
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