My Story -

I have 54 SP150's broken into 3 groups of 18 each feeding a STR2500XRUP.

I installed my own system a year ago and had numerous problems with the ST2500' sthat I received including units that arrived DOA and with other operational problems. During my initial installation I had to make 5 change outs of my initial 3 inverters - mostly DOA.

When I found out about the upgrade units I was excited to see improved performance, since I have noticed that the airplane trails (we live near an airport) and clouds in our area made a siginificant performance differance.

Well this time I had Graham Owen (a solar installer) install the units and everything worked great. I then went out of town for 1.5 weeks. I come back and one unit is working great, one is not operating and one is working at about 25% of the operating unit.

I check volatage on all leads and everything is within specs. After I pull the leads to test the margianlly operational unit, it does not fire back up.

Xantrex - I am so very disapointed, that I have to go through this process some more, I am loosing out on some great solar power creating weather......

Josh

Hi,

First off , this isn't Xantrex tech support, but is my private site ...

Second , as you can tell by reading others , this is NOT the norm , the New sunties work and there are no design or performance issues. I have been in close contact with the factory and there have been almost no DOA units , so something is NOT right with those two units or how they have been installed

Without a better breakdown of your system , it is hard for me to give you specifics to debug your problems.

The most obvious question I have is how are you panels configured ?. you say you have 18 panels per suntie , that would mean you have 9 pairs going into a six input combiner board ? , if this is true maybe you installer doubled up panels on input and hence would be blowing the fuses due to over current conditions. This would explain the drop in power. A simple test is to pull the fuses and one by one add them back to verify their live. Another good test , is to again pull all the fuses and test the short circuit current of each string.

please post your configurations and I'll see if I can give you some more direction

Henry [img]images/smiles/icon_smile.gif[/img]

I am sorry if I miss posted, I guess I needed to vent for a minute.

Each group of 18 is broken into 3 groups of 6 (in pairs of two) through a combiner box with three leads going to each inverter. I get between 76-79 volts on each feed to the inverter.

I have also checked all of the fuses, and each of the ffeds from the panels and am getting between 76-79 volts and am acually get 76-79 volts out of the combiner box in the inverter, so I think the problem lies in the top half of the inverter.

I appreciate any help, I will call tech support in the morning....

Hi Joshua,

I can understand your frustration coming home and not seeing things work , I just have a hard time believing two inverters just died and it's all Xantrex's fault.

Your not making sense on your wiring explanation and I strongly beleive this is where your problems might be.

You state you are externally combining the panels into groups of three , then sending this to the inverter ... this will exceed the current rating of fuse on the combiner input , especially when you get edge of cloud current boost of 125%. If I understand your connections , each inverter will have 6 wires as inputs , three + three - , so your putting in 2700 watts thru 3 fuses ... [img]images/smiles/icon_eek.gif[/img] [img]images/smiles/icon_eek.gif[/img]

If I've got this right and this is correct , then this will explain the inverter with 25% output , you've blown fuses on the suntie combiner board

On the dead inverter (when you got home), you need to verify that there is DC power going to the power-board. This sounds basic , but have you verified the output of the DC breakers ? DO any of the leds on the CPU card light up ? , what exactly is shown on the LCD if anything ?

You are also violating NEC and UL current ratings on your solar panels if in the external combiner , they dont have seperate fuses for each of the three stings , if you get partial shading , you'll be back feeding current from the other two strings .. this will also void your warrenty on the panels

You mention voltages comming from the external combinors ... that doesn't mean much since you could have all except a single string connected and still get the exact same VOC voltage , VOC is voltage , open circuit , or with no load.

You need to do some very basic checking before calling xantrex , I'd start by

1) pull all the fuses on the suntie

2) verify the short circuit current , this can be done simply by connecting an amp meter from the "+" to the common "-" for each string , you will be shorting out the panels thru the amp meter , this will verify that there is avalible power and should be the same for each string (about 17 amps at solar noon for three sets combined)

3) verify the fuses are good , use a DVM and check the resistance

4) connect one string at a time (so in your case three trys) , which means install a single fuse on the ST combinor board , verify , DC voltage going into the power board , output of DC/GFI breakers

At this point if there is verified , good power , you can THEN say , damm suntie/xantrex.

If I am correct on your wiring ... you need you have a talk with your installer and resolve the incorrect overload/fusing using only 3 of the 6 inputs ... this won't cut it

Let me know the results of your tests , I'll be happy to help further if necessary

Henry [img]images/smiles/icon_razz.gif[/img] [img]images/smiles/icon_razz.gif[/img]

First of all, I want to thank you very much for taking the time to even reply - I really appreciate any help. If I am taking up too much of your time tell me and I will stop bugging you.

I can answer some of your questions that you listed and will work on getting the rest answered. If you are interested I can fax you a layout of my system it was designed by Sunwise. My previous inverters(STXR2500's) have worked for the last 9 months without a problem. I too find it odd that there are issues with two inverters at the same time.

All of the panels are breakerd in the combiner boxes. I am getting voltage out of the internal STXR 2500 combiner boxes (past the fuses), but I don't have an AMP meter (just voltage), so I will pick one up.

The three input problem is interesting that you bring up because we discussed this and they insurred me that this was fine, because we would never hit the 2500 watts - I can show you on the drawing how it is set up.

Thanks again,

Josh

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That is why I have this site , a no BS place for everyone to help out

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Then why did you get the upgrades [img]images/smiles/icon_biggrin.gif[/img] [img]images/smiles/icon_biggrin.gif[/img] (sic) Well , the old XR's would not put out as much power and hence wouldn't stress the input fuses , they don't react at all to edge of cloud effects , more than likey the out goes to zero on the old XR's

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Verify EACH fuse passes current and the current test as I decribed and then verify that power is going into the power board , the red and white wires , the red comming from the 100 amp DC break/gfi combo

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Do the math for 1000wmsq (STC) for current , then add 25% for edge of cloud. My KC-120's are rated at 7.2 amps and I see 8.5 to 9 amps in some conditions ... your most defiantly going to exceed the 20 amp rating of the single combinor inputs.

Sunwise is full of it if they claim you won't ever get your STC DC rating , remember , its DC going thru the fuses. 18 , 150 watt panels is 2700 watts , and with edge of cloud you push over 3kW ...also its amps , not watts that will blow the fuses , hot weather lovers the voltage , amps actually increase ! (about 10 to 1 to voltage decrease)

Also , if your panels are at your roof pitch , you are probably at the pefect angle to the sun right now.

Re-read the previous posts , make the measurements as close to solar noon as you can , check the outputs of the DC breakers (suntie) decribe what exactly is display on the LCD and LEDs of the CPU card

Takes some time and read thru the older posts on system sizes and the power were all seeing ... you'll understand why there is a problem

Henry

Yes , if every panel pair is breakered , by all means use the bypass lugs !! ... wonder why that didn't occur to me !

If you have verified DC is on the output side of both the 100 amp DC breaker and gfi breaker and entering the power board , sounds like a dead inverter. For this call Xantrex and bitch them out and have them get a ship a head replacement. You only mention the AC , having power on both sides ... follow the red wire as it goes from the combiner , to the two breakers and then to the power board. If you take off the cover upper cover , measure there that you have DC just to be certian , its not a lose feed wire.

Rewire your external combiners to wire to the bypass lugs on the sunite internal combiner board and you should be all set

Henry

I have verified volatage on both outputs of the DC side breakers, but the inverter is still dead. Xantrex is shipping out a new inverter UPS Red.

I will move the inputs tonight to the bypass lugs.

THANKS!!!!

Hi Joshua,

You can combine the three strings if they are wired with #6 wire (or possably #8 depending on wire type) without additional fuses or breakers. If one of the string wires can not handle 1.56 times the short circuit current of all of the other strings combined, then you will need additional circuit protection. Just imagine where the current will flow if one of the string cables shorts near the array.

Ron

The new combiner boxes in the upgraded STXRs have a bypass terminal.

It sounds like there are external combiner boxes (presumably with fuses or breakers) already, I would simply do combining in the external combiners and feed the inverter via the bypass terminals and avoid the fused inputs.

If I understand the system correctly there are 18 modules per inverter, that means 9 panels (SP150 are 24V nominal). If 3 inputs are going into inverter then the panels were combined into sets of 3. According to the SP150 spec sheet, short circuit is 4.8 amps. So the input current short circuit current is 14.4 amps. The fuse needs to handle 1.56 times the short circuit current (per NEC and UL 1703) and that would be 22.46 amps.

arnold