Non-functioning decade old 10kW Grid-interactive system

Han Solar

I found this forum while searching for batteries and was impressed by the expertise being shared here. So, I joined to solicit ideas on what to do with my non-functioning system.

PV: 100 AstroPower-100, each rated for 100W, 56 facing S, 44 facing W, combined into 5 strings
CC: 5 Xantrex Trace C40
Inverter: 2 Xantrex Trace SW5548
Battery: 12 SunXtender PVX12100T, arranged in 3 banks @48V, so each bank capacity 100Ah@24h
Critical Load: dozen lights, frig/freezer(EnergyStar), computer/TV, no HVAC
House: 4400 sf Ranch style, 2HVAC (5ton SEER13 + 3.5ton SEER8?), swimming pool pump, sm 600gal. koi pond pump
Elec Usage: annual 11000kWh net-metering (amount of solar output unknown) with SoCal Edison


I bought the house in 2007 and the system was already in place and running. Based on the components' manufacturer plate, the system was probably installed in 2001, so it is now 10 years old. System seemed to ran fine initially (meter spinning backwards). After house remodelling 2007-8 requiring relocation of 8 PV panels, system began to exhibit frequent instability (AC output voltage rapid cyclic fluctuation) when transitiioning to full sun around 10am, or on very cloudy days.

2009 one of the battery exploded so an electrician was called. He reconfigured the battery banks to use only 8 batteries in 2 banks. Through 2010, I rotated dead battery (as measured by excessively low open circuit voltage) out and reused the best of the remaining batteries every few month. By last fall, only 6 of original 12 batteries have sufficient charge and the system would no longer function. Within a few minutes after turning the inverters on, one shuts off with an "OVER CURRENT" error.

Since 2010, I have contacted 2 independent solar installers, 1 BP Solar dealer-electrician, and 2 major companies (SunPower & SunWize) to come and evaluate my system and give me proposal for restoring/upgrading the system to reduce my electric bill (now frequently in the most expensive Tier V range). 3 of the 5 vendors declined to have any thing to do with a system they did not install. The BP dealer proposed to add a separate 6kW grid-tie system, and replace the batteries onn the old system. SunPower proposed to remove 45 or so of the old PV panels and use the roof space for a new separate 7kW grid-tie system, and reconfigure the remaining old panels into a single inverter grid-interactive with generator backup.

I get the feeling that vendors don't want to fix or restore my old system, perhaps because they have no experience or expertise with the components that are no longer in production. I also get a very strong feeling that vendors really want to sell me a new grid-tie system, probably because that's where the best profit margin resides.

My goals are to have backup power during emergency (e.g. earthquake, wind storm) and to reduce my electric bill into the lower cost Tier II range. So, I have considered these options:

#1 - Abandon solar system and just install a backup generator, replace the old SEER8 HVAC, replace pool pump
#2 - Replace only batteries (8 or 12?) and hope that the inverters are still functioning and can go for a few more years
#3 - Replace/add panels/inverter(s) such as was proposed by some vendor

I was heading towards option #2 as a DIY project because that has the lowest cash outlay, but am uncertain if the inverter(s) might be failing. What are your thoughts?

Cariboocoot

Re: Non-functioning decade old 10kW Grid-interactive system

Welcome to the forum.

Probably the first problem is the batteries. Their age is unknown, although it is doubtful they are as old as the whole system. Ten years is quite a long time for basic batteries. The bank capacity itself, even if at 100% (extremely doubtful) is a tad small for a 5 kW GT inverter. You can charge the batteries up, let them sit, and see if they hold Voltage. You could also do a discharge test on them, but that is somewhat more complicated.

Another issue is moving the panels. They may have been moved "out of the sun" so to speak and are no longer contributing as much as they did. Panels do go down in power a bit over time, but we here haven't found this to be as severe as manufacturers originally anticipated.

Then there's the SW series inverters. These were very good inverters, but time is the enemy of us all. Many SW units have failed, and repair isn't a practical option for the most part.

Unless you have some really good utility/government incentives for going GT (or even if you do) your best bet will be to look into conservation. Changing out the HVAC and pool pump may be far cheaper than replacing the GT solar.

Others will have different perspective/input. Some of them have more experience with GT, Xantrex equipment, and HVAC systems. Me, I'm off-grid, use Outback stuff, and open the window for A/C.

Polaraco

Re: Non-functioning decade old 10kW Grid-interactive system

Cariboocoot wrote: »

Welcome to the forum.

Probably the first problem is the batteries. Their age is unknown, although it is doubtful they are as old as the whole system. Ten years is quite a long time for basic batteries. The bank capacity itself, even if at 100% (extremely doubtful) is a tad small for a 5 kW GT inverter. You can charge the batteries up, let them sit, and see if they hold Voltage. You could also do a discharge test on them, but that is somewhat more complicated.

Another issue is moving the panels. They may have been moved "out of the sun" so to speak and are no longer contributing as much as they did. Panels do go down in power a bit over time, but we here haven't found this to be as severe as manufacturers originally anticipated.

Then there's the SW series inverters. These were very good inverters, but time is the enemy of us all. Many SW units have failed, and repair isn't a practical option for the most part.

Unless you have some really good utility/government incentives for going GT (or even if you do) your best bet will be to look into conservation. Changing out the HVAC and pool pump may be far cheaper than replacing the GT solar.

Others will have different perspective/input. Some of them have more experience with GT, Xantrex equipment, and HVAC systems. Me, I'm off-grid, use Outback stuff, and open the window for A/C.

I agree. Your troubles seemed to have started after some time, so I would say start with the batteries.

The inverters are electronics. Typical electronics Mean time is 10 years. You may want to look at them at the same time.

Maybe watching the sun as it aporaches the panels might help. Maybe the angle needs to be changed. Or maybe a tracker might help. You have to monitor it

BB.

Re: Non-functioning decade old 10kW Grid-interactive system

Yea, 10 years and you are looking at Battery Replacement and new electronics (charge controllers, inverter) in the near future.

The big issue with generating your own power. You are on the hook for maintenance charges and capital improvement costs.

Now is the time to decide--Put more money into the existing system; upgrade with new inverter/chargers (much better stuff these days at pretty good pricing); or changing the whole scheme (pure Grid Tied with Natural Gas/Propane/Diesel/Gasoline backup genset).

Is your grid power poor enough that you need a full "Hybrid" solar power system (grid tie when utility is up, off grid when utility power is down), or would a pure GT system + Generator do what you need for much less money.

And, as always with solar power (or even utility power), review you current power usage and see if conservation measures can be done. It is almost always better to spend money on conservation before spending it on PV Power.

-Bill

solarvic

Re: Non-functioning decade old 10kW Grid-interactive system

I don,t have any experience with your problem. I don,t see how all your solarpanels could be useless. I would check the output of the solar panels. If they work use them. They should have a longer lifetime than 10 years. If your solar panels are good then you could build a grid tied system from there. Get 1 gti inverter for south facing panels and 1 gt inverter for the west facing ones. and get a generator for power outages. Probably a lot cheaper than replacing all of the off grid components. Most of your offgrid equipment is either probably broken or near its lifes end and is probably obsolete anyway, especially the charge controlers. If you still want to stay with the battery system then first check batterys. If they are bad I would still want to make sure solar is making power. Then see if charge controlers work. Then if the inverters work. If it is just the batterys, you could buy new batterys first and then rebuild the rest as things quit or wear out. First updates after batterys is get new solar controlers, midnight or outback. Then save for new inverters. Just some ideas from a solar user. Probably going the gt route gives you the most return especially if the battery system is at end of life. :Dsolarvic:D I am slow at typing a post but I agree with bill. He gave you good advice about GTI which is what I would do if your power is preety stable.

Windsun

Re: Non-functioning decade old 10kW Grid-interactive system

First thing you need to do is make sure that all of the solar panels are still working. The panels themselves are probably OK - they usually last 20-50 years - but the ones that got moved could have gotten damaged and/or miswired. Or as someone noted, in the wrong place and getting no sun.

2nd thing is to realize that 90% of the solar companies out there don't know diddly crap about battery based systems, and they will usually try to avoid even dealing with them.

You have roughly $9,000 worth of panels there (probably cost $40,000 when bought), so you have two options - sell them or use them. As used 12 volt panels you could get $75 to $100 each, maybe a little more. On the other hand, you could generate around 40 Kilowatt-hours per day if they were hooked up to a grid tie system.

A lot of what you do depends on how good you are with electrical - if you can do some of the work yourself, probably worth using them. If not, I would take them off carefully so as to not break them, and put them up for sale. Use that money to pay for part of a new grid tie system with a generator backup, and no batteries. The old panels will probably not meet current NEC or even UL codes, so you might have trouble getting permits if that is an issue in your area.

Photowhit

Re: Non-functioning decade old 10kW Grid-interactive system

As an existing Grid tied system, I don't think they would have to requalify the panels.

Sounds like you need to keep hunting around for a solar qualified electrician, I don't know or understand how the SW inverters backfeed into the grid, but there is someone out there that can figure out what is wrong, I'd keep looking. I would think one part of the system has failed, and this is some hybrid system since it has batteries as well.

If in the situation, I would suggest trying to find original information, perhaps even the original installer. If looking for quotes I would look at reconfiguring for a grid tie only, the panel AP-100 are UL listed and look to bedesigned to handle 600V nominal also it appears they are unevenly configured currently, 5 strings with 44 facing one direction and 56 another, just doesn't work, IMHO. Perhaps they were redistributed when moved? Also since C40 is a standard PWM charge controller, it can only handle charging current for 48volts or strings of 4 panels so they are likely combined some where else and brought down in 5 strings @68 volts. I think the must backfeed via the inverters.

....as I said I am ignorant of this sytem. Best guess is they charge the batteries until full then back feed the grid. Though Xantrex does not appear to provide support, you can find manuals for the SW5548 by searching, Sw5548 Pdf, I could only find the manual at other solar retailers so I didn't want to provide a direct link, I'd be glad to help if you can't find it in a PM. I did find that the SW5548 is nolonger code compliant but if it is installed and exists all that is needed is to present a charged bank, which could be quite small. Replacing the inverters (and the Charge controllers) with grid tie units or a single unit would not be cheap, but might be the best cost over time solution. Likely the C40's are mostly or all still working, they tend to be very dependable. (I'd be interested if you choose to replace them, cheap of course) I took a 20+ year old CC out of service 4 years ago, I replaced it with a design similar to the C60 which was 10 years old when installed and died due to a kamikaze lady bug attack. Replace with another 10+ year old unit.


They exist and are mounted and just need to wired correctly. I'd dump the backup, and likely the inverters (or use a genny as others have suggested, and you likely have most of the connection existing) Look into wiring them into high voltage strings and purchase a current/modern Grid tie inverter. Having someone find where the panels are combined and rewire them (likely need to add a combiner box w/fusing or breakers) To find someone I'd ask the electrical inspector, for a handfull of suggestions, which he can't do, but maybe he can list people in the local area who are qualified, or perhaps you could buy him/her lunch and talk 'off the record'.

This advice is worth less than you paid for it, but thought I'd post my ideas. If you have some idea of what you were saving with the old system the new Grid tie systems all use MPPT technology and likely you'll see 20+% more savings + a bit more since you won't have to top off the batteries, and of course most of the solar is during peak times...

jagec

Re: Non-functioning decade old 10kW Grid-interactive system

I'd hook a SB-4000 onto the 44-panel array (2 strings), a SB-5000 onto the 56-panel array (2 strings), and just use a generator for power outages. I ran the numbers through Sunny Design, and assuming that all panels are at a 30-degree angle (with the 44-panel array facing due west and the 56-panel array facing due south, in LA), you should be OK on voltages year-round, and generate about 13,500 kWh a year (probably a little optimistic), more than enough to offset your consumption. I used the datasheet from Photowhit's post for the AP-100s, since they aren't listed in the software.

For about $5k in equipment, minus whatever you can get from the sale of the old charge controllers and batteries, you'll have your system fully up and running, without having to move any panels or take anything down. You'll still need an electrician, of course.

solarvic

Re: Non-functioning decade old 10kW Grid-interactive system

I located the spec for the astro power model AP-1oo. I was doing fronius inverters which are good too. If you do fronius inverters make sure you use the IG- Plus models which run at 600 vdc. The older IG models limit to 500 vdc. I have some of both kind and think the Ig -plus models are better. AP-100 spec. jageg,s advice is good and is cheaper than new batterys.
STC watts 100 watts,
PTRC watts 88 watts,
VOC 20.10vdc,
VNP 16.1vdc,
IMP 6.2 amp So if anyone wants to do any research on any different inverters ect. Enjoy :Dsolarvic:D

RCinFLA

Re: Non-functioning decade old 10kW Grid-interactive system

Here is manual.

http://www.xantrex.com/documents/Discontinued-Products/SW2512MC-SW4024MC2UserGuide.pdf

Two units probably rigged as series stacked for 240 vac.

Batteries are likely bad.

Han Solar

Re: Non-functioning decade old 10kW Grid-interactive system

Thanks for all the great responses. As was pointed out several times, I should be considering another option:

#4 - Replace inverters and reuse existing PV panels in a pure grid-tie setup, separately install backup generator

This option appeals as less cash outlay than #1 or #3, and better than #2 as the old inverters are at or near end-of-life. While there is no easy way for me to check whether each and every 100 panels are working, I am able to measure between 65-80VDC from PV inputs to each of 5 charge controller on a cloudy/overcast morning.

About pure GT setup, specific suggestions were to have separate inverters for S and W panels. Is that to get best performance? While the 56 S panels on the main roof are all at same pitch, the W panels are at three slightly different pitch (8 on house, 8 on patio, 28 on garage). I can trace the 28 garage panels to a combiner/fuse box, and the 8 patio panels to another. There are 3 other combiner/fuse boxes for the main roof, but I haven't figured out how the 64 main roof panels are strung into them. Could there be boxes under the panels or in the attic hidden from plain view?

Based on experience, anticipated need for backup power is a few hours of black/brown outs every 4-6 months, and one multi-day blackout every 5-7 years during major emergency (storm, fire, earthquake, etc.). Which generator and switching should I consider? Co-workers have spoke well of Generac and Honday (said to be very quiet).

Great idea on asking city building inspector about electrician. I was able to get a complete list of permitted solar project for my zip code over the last 4 years, about 70. Will have to research each project's contractor to see if contractor is licensed as electrician or solar installer. It was easily seen on a quick glance that about half the projects used SMA brand inverter. Does that speak to SMA's price or quality?

Cariboocoot

Re: Non-functioning decade old 10kW Grid-interactive system

SMA inverters are very dependable. They've been around quite a while and know what they're doing. They are perhaps more expensive than some others, but the quality is there.

So you've got a minimum of 65 Volts * 5 = 325 Volts. In total that is enough to run most GT inverters. The trouble is it's not all one array. Since each GTI has its own MPPT input, having arrays that face in different directions and at different angles will mean one inverter alone will not be able to utilize all panels to their maximum potential. The panels that are in an aspect which provides less power at the moment will inevitable cause a drop in output from the other.

You can use PV Watts to try out some different scenarios with panel and inverter combinations. Ideally microinverters could solve the whole problem of angle/direction but your old 100 Watt panels won't be on the "approved" list of panels for them, and you'd have to run two together to make the usual 200 Watt equivalent for something like an Enphase.

solarvic

Re: Non-functioning decade old 10kW Grid-interactive system

Yes the reason you need the 2 separate inverters is because of the panels faceing south and west. The panels facing south will start making power sooner and quit sooner. The west facing ones will start later and finish later. The panels that are a little different elevations won,t make that much difference as long as it they are as close as you can get them. I only have experience with the fronius inverters I have but think the later model ones that Model no. start with IG-plus has a steadier output than the IG models. Sma are rated good also. :Dsolarvic:D

BB.

Re: Non-functioning decade old 10kW Grid-interactive system

Generac appears to be variable... The smaller units are usually not very good or long lasting. There are larger units which can be OK. Pick a size and research the specific models.

Honda seems to be very good in general. The eu1000i/eu2000i are great portable units (900 watt and 1,600 watt ratings) and very quiet. And unlike many smaller generators, these will should last 2,000 hours with just oil and filter changes (and a new spark plug once in a while). One poster here has ~6,000 hours on his eu1000i (I guess burns a little oil now--but still starts). These are inverter generators. Can slow engine speed down with light loads ("ECO Throttle": less fuel and less noise, longer life) and solid 60 Hz power. They do not do well starting large loads (big well pumps, large circular saws)--But they do work OK for their size.

Yamaha also has similar products and good quality.

In the end, it depends on your needs. I only need a 1,600 watt genset (Honda eu2000i)--just enough for a couple fridges and some lights, etc. Expect to use ~2 gallons of fuel per day.

A larger genset (8 kW-10 kW minimum whole home with automatic start/transfer switches) can use 1-2+ gallons of gasoline (or equivalent in natural gas) per hour. If you need that much power--It is worth the price (if you can manage the fuel storage).

If not, even with a "cheap" 3.5 to 5/7 kW portable genset, you are looking at using a 1/2 gallon per hour of fuel--5-10 gallons per day is not unusual. Noisy, and trying to find a service station with fuel AND electricity may not be easy with a large power outage/emergency. Plus, the inexpensive generators are NOISY. And I would not want to run one unless I wanted everyone within a block knowing exactly who had power and a generator.

Spend the money on a quiet a reliable generator sized to your needs. If you have propane or natural gas (I don't use natural gas because it may fail in an earthquake), look for a new or used RV generator. The are a bit smaller than a typical whole home backup unit, and are quiet and pretty reliable with electric start. I know one guy that installed a backup RV generator under his home's crawl space (Not sure I would do that--But it worked for him).

Propane is great for storage, but bulky (gasoline and diesel are heavier per gallon and have more heat energy per gallon). Yamaha (I think) has a propane factory generator, there are few companies that will convert Hondas to propane (as well as after market conversion kids--Honda does not warranty conversions).

I use a fuel stabilizer in my gasoline and recycle back to my car after a year--And I already had a 20% return on my gasoline storage just since last December.

-Bill

Windsun

Re: Non-functioning decade old 10kW Grid-interactive system

We prefer the Fronius and SMA inverters. Xantrex (Schneider) has had a few problems in the past with availability, so we do not stock the full line of their grid tie inverters.

Han Solar

Re: Non-functioning decade old 10kW Grid-interactive system

Measured the PV array inputs at the charge controller at noon full sun, go 68VDC on one and 74VDC on other four. The 68VDC array is consistently the lowest voltage array. Does this suggest that string contains damaged/miswired panel?

BB.

Re: Non-functioning decade old 10kW Grid-interactive system

Your system was (I think) built using PWM charge controllers... More or less, these are big switches. Turns "on" when current is needed and turns "off" when not. May do this hundreds of times a second (electronic switching--Pulse Width Modulation--i.e., switch on more than it is off--more average current. Switch off more than it is on--less average current).

So, the lowest voltage array may simply have its charge controller turned on Most/All of the time. The higher voltage arrays may have their charge controller "off" most of the time--or you may have a open charge controller (never turns on), an open wiring connection somewhere, or the controller simple turns "off" at a slightly lower voltage than the other).

This stuff can have you pulling your hair out in no time... Depending what is going on, low voltage may be "good" or it may be "bad".

I would suggest that you buy/borrow a DC Current Clamp Meter (here is a "cheap one" that works pretty well). You just clip it over one of the array wires and measure the current. Also, DC Current Clamps (most DC meters support AC current too), are very safe to use. Most current meters otherwise require you to break open a connection and wire the meter in series (typically 10 amps maximum for standard digital multi meter). Exposing you to both high current and high voltage--Can be quite dangerous at times (even if you know what you are doing).

Now you will know both current and voltage as you check through your system. More or less, current is very important here. If you have poor connections, the current will be low to near zero. You can go to each panel/series string, and measure the current in each set. Very quickly figuring out which strings/panels/batteries are not carrying their share of the current.

-Bill

solarvic

Re: Non-functioning decade old 10kW Grid-interactive system

Han Solar wrote: »

Measured the PV array inputs at the charge controller at noon full sun, go 68VDC on one and 74VDC on other four. The 68VDC array is consistently the lowest voltage array. Does this suggest that string contains damaged/miswired panel?

Since you checked at high noon the panels aimed south probably have the highest voltage and should turn on sooner in the morning. The west ones might be a little less and the one that has the elevation setting might be different. Later in the day the west facing panels should have higher output than the south facing ones and have pit out a little longer. :Dsolarvic:D

Han Solar

Re: Non-functioning decade old 10kW Grid-interactive system

I opened all five combiner boxes (Xantrex TCB-10) and found that each of the boxes is combining five PV inputs. So, 5x5=25 substrings of 4 modules.
The modules are connected serially into the substrings on the roof, and only one pair of wire feeds from each substring.
Since there are 44 west modules and 56 south modules, one of the box must be combining 4 south substrings with 1 west substring!
Now, how to recombine the substrings to feed the new inverters, with minimal new wiring?

It was suggested by jagec that I hook a 4kW inverter to the 44 west modules and a 5kW for the 56 south modules.
The 56 divides evenly into 2 strings of 28 substrings, but the 44 modules are presently wired into 11 substrings.
Is it OK to have strings of different length (20 + 24 modules) feeding into the 4kW inverter?
If not, would it be easier to just not use 4 modules and make 2 strings of 5 substrings (20 + 20 modules) rather than tyring to split that 11th substring up.
At 40 modules, a 3kW inverter like SB3000 might suffice.
As for the 5kW inverter, I tried a SB5000 on Sunny Design and got a max PV voltage overload warning.
I don't know how Sunny Desing is calculating max PV voltage to be 638V, exceeding the 600V rating.

BB.

Re: Non-functioning decade old 10kW Grid-interactive system

No, I would not use a 20+24 string--The Vmp-strings are too different (and you will probably get less than optimum harvest--maybe 20% less, or worse, harvest). 10% or less Vmp would allow 20-22 -- But even then--I probably would pull the 4 extra panels and save them as spares in case anything else fails.

-Bill

ggunn

Re: Non-functioning decade old 10kW Grid-interactive system

Han Solar wrote: »

I found this forum while searching for batteries and was impressed by the expertise being shared here. So, I joined to solicit ideas on what to do with my non-functioning system.

PV: 100 AstroPower-100, each rated for 100W, 56 facing S, 44 facing W, combined into 5 strings

100 modules in 5 strings implies 20 modules per string. If that is true, 56 facing south and 44 facing west means that at least one string straddles the split with some facing south and some facing west. This is not good. You can get away with some complete strings facing west and some facing south on the same inverter because the voltages will be very close, and some strings will simply generate more current depending on the time of day. The MPPT will be a bit off optimal but you won't lose that much. Any string with some modules facing south and some facing west, however, will be significantly impaired because the current in that string will always be limited to that which is generated by the portion of the string with the less direct sunlight.

raydias

Re: Non-functioning decade old 10kW Grid-interactive system

Have you looked at the Power-one inverters that have 2 separate MPPT

http://www.power-one.com/renewable-energy/products/solar/string-inverters

If you have multiple facing strings you can get 2 of the 5kw versions and that would give you 4 separate MPPT connections.

just my 2 cents.

ggunn

Re: Non-functioning decade old 10kW Grid-interactive system

raydias wrote: »

Have you looked at the Power-one inverters that have 2 separate MPPT

http://www.power-one.com/renewable-energy/products/solar/string-inverters

If you have multiple facing strings you can get 2 of the 5kw versions and that would give you 4 separate MPPT connections.

just my 2 cents.

That won't help a string in which some panels face west and some face south. As to the idea of buying inverters with multiple MPPT inputs, one should analyze the cost vs. the benefit of doing that before spending the money. Even with two strings facing 90 degrees from each other, for most of the day the optimum MPPT points would not be all that different.

raydias

Re: Non-functioning decade old 10kW Grid-interactive system

ggunn wrote: »

That won't help a string in which some panels face west and some face south. As to the idea of buying inverters with multiple MPPT inputs, one should analyze the cost vs. the benefit of doing that before spending the money. Even with two strings facing 90 degrees from each other, for most of the day the optimum MPPT points would not be all that different.

Reason i suggested the 2 x 5k inverters. that would allow him to break the panels into 4 strings which should solve the mismatch orientation. As for cost I agree. I was more focused on the orientation issues and making a suggestion accordingly.

Polaraco

Re: Non-functioning decade old 10kW Grid-interactive system

Either I'm slipping, or I'm slipping. (Either one is true) My absorption rate has gone into the dumper.

Can you re-explain that for a tired old man? I don't quite understand what you are saying. I have panels facing due south and vertical panels facing due west. They get a direct unobstructed direct evening sun. West is 500 Watts. The shaddowing is minimal during the transition. So far. I just finished the install. At 5:00 I am seeing 75 Amps from 2500 Watts. 500 west. So far.

ggunn

Re: Non-functioning decade old 10kW Grid-interactive system

Polaraco wrote: »

Either I'm slipping, or I'm slipping. (Either one is true) My absorption rate has gone into the dumper.

Can you re-explain that for a tired old man? I don't quite understand what you are saying. I have panels facing due south and vertical panels facing due west. They get a direct unobstructed direct evening sun. West is 500 Watts. The shaddowing is minimal during the transition. So far. I just finished the install. At 5:00 I am seeing 75 Amps from 2500 Watts. 500 west. So far.

If what you are asking about is the penalty for having a string with both south and west facing modules, it's because the current through a module is dependent of the irradiance on that module and the current in a string can only be that of the lowest producing module. In the middle of the day, the south facing modules have strong irradiance while the west facing ones do not, so the west facing modules restrict the current in the string. Late in the day the west facing modules are getting great sunlight, but the south facing ones are not, so the south facing modules throttle down the current. That string will never produce at its top potential because one portion or the other is always restricting the current. The best time for it will be when the sun is midway between south and west when both faces are producing the same amount of current, though it will be lower than it would be if they were all getting direct sunlight at the same time.

Polaraco

Re: Non-functioning decade old 10kW Grid-interactive system

OK I understand what you were saying now. I knew what you were saying all along. Just not in those words. I had a Prof that talked like that. LOL

In my case there is a point where the sun over laps for a couple of hours. The sun will be hitting my vertical west on an angle, and not as productive. But the panels will be getting the full lumes. I'm working on it though. I was looking at a way to track the flat panels. If I go to the ground, the will be blinded. Need to work on a blind type affair. But when I retire and have nothing else to do.

With limited space it's hard to work what I need. My Garage has the biggest south space. That will be getting a few panels as well. Just going to go straight grid tie and back feed from the Garage to the house.

Thanks for clearing that up for me.

Han Solar

Re: Non-functioning decade old 10kW Grid-interactive system

I now have four proposals (all from electricians that do solar projects in my locale) for replacing the inverters and reconfiguring to a pure grid tie.

In descending cost:

1) SunPower 5000m for 56 south modules + SunPower 4000m for 44 west modules
2) Relocate 6 south modules to west to reduce partial shading; Pair of SunnyBoy 5000 one for each 50 modules
3) Power-One 6000 for 56 south modules + Power-One 4.2 for 44 west modules
4) SB5000 for 56 south modules + SB5000 for 44 west modules

The bids are within 15% of each other. SunPower 5000m and SunnyBoy 5000 are the same inverter. So, I would appreciate any comments on SMA vs. Power-One, on the configuration and optimal match of inverter to module.

solarvic

Re: Non-functioning decade old 10kW Grid-interactive system

Here is a description of a sunpower inverter where they say it is a rebranded fronius plus inverter. I have a fronius 3000 plus inverter that I like. http://www.ebay.com/itm/SunPower-SPR-8000f-Fronius-IG-Plus-7-5-1-UNI-Solar-Inverter-Data-Monitoring-/120884927686?pt=LH_DefaultDomain_0&hash=item1c254d9cc6 This is for informational purposes. :Dsolarvic:D

autoxsteve

Re: Non-functioning decade old 10kW Grid-interactive system

I have a Fronius inverter that I like and Power One has come on the market recently and I've heard good things.

Ask for references of the suppliers/contractors and go talk to the people they've done work for. I bet your answer will be waiting with their inputs.

JohnO

Re: Non-functioning decade old 10kW Grid-interactive system

Han Solar wrote: »

I found this forum while searching for batteries and was impressed by the expertise being shared here. So, I joined to solicit ideas on what to do with my non-functioning system.

PV: 100 AstroPower-100, each rated for 100W, 56 facing S, 44 facing W, combined into 5 strings
CC: 5 Xantrex Trace C40
Inverter: 2 Xantrex Trace SW5548

<SNIP>

My goals are to have backup power during emergency (e.g. earthquake, wind storm) and to reduce my electric bill into the lower cost Tier II range. So, I have considered these options:

#1 - Abandon solar system and just install a backup generator, replace the old SEER8 HVAC, replace pool pump
#2 - Replace only batteries (8 or 12?) and hope that the inverters are still functioning and can go for a few more years
#3 - Replace/add panels/inverter(s) such as was proposed by some vendor

I was heading towards option #2 as a DIY project because that has the lowest cash outlay, but am uncertain if the inverter(s) might be failing. What are your thoughts?

Hi HanSolar,

I have a SW5548 system installed in 2002 and it's still running fine, though the batteries are quite "weak" - they used to power the critical loads for 18-24 hours, but now only 4-6 hours. Time for new batteries...

Reading all of the posts on this thread, my question is: what did you do with your two SW5548s and five C40s? At some time mine will fail, and I'd love to have a unit or two that I could use for parts. I'm not sure where you are located, but I think you said you were on SoCalEdison. I'm in Santa Cruz, so shipping shouldn't be too expensive, if you haven't sent them to the ewaste folks yet...