James Cormican's posts

has anyone noticed problems with off grid systems in which a properly installed hardwire modified sine wave inverter is tripping afci breakers for bedroom circuits but not affecting the other breakers?

if so please tell, specificity on make and model of inverter and ac panel/breakers appreciated.

james
altE staff

interesting, thanks for sharing.  i had not heard of that model.  since it has a j box, i would call sanyo and see what they have to say.  i would bet they would have the diodes available or at least could tell you the specs.

james
altE staff

which exact model of sanyo module do you have?  how many cells does it have?  what type of frame, and what type of wiring ( junction box, solarline 1, solarline 2)?

that info would help, i dont recall a sanyo 24v module of recent vintage.

it is possible for bypass diodes to fail although it is rare, generally the manufacturer would have those available if it is a j-box style module.  the techs at the module manufacturer would likely want to know measured voc, and isc apart from the array, as well as the serial number on the module and the irradiance level at test time if you have the cabability of measuring it.

james
altE staff

right on. 

in james j case they are roof mounted, so in theory at site of first enclosure (combiner or pass thru)on roof,  the egc, along with pv source circuit wires, transition from bare copper and use-2/rhw-2 respectively, to more "normal" conductors like thhn or so run together in conduit as pv output circuit, as Bruce F suggests.

james
altE staff

hi bruce,

nice post.�  the one thing i would like to add is that in some cases it is possible to have egc and grounding electrode separate from that of the remainder of a system, although not for james j with his modules on a building (that contains the bos).

here is a link to an old john wiles article that describes the "seperately derived system" in which i believe in cases of physical distance between array and the building which it serves, the equipment grounding may occur at the array, go to its own grounding electrode while not carrying egc in the conduit to the building.�  upon reaching the building the BOS equipment is all bonded as appropriate and tied in with the building's grounding system and electrode(s).

http://www.nmsu.edu/~tdi/pdf-resources/cc74.pdf

looks like this is still valid in 690.47D 2008 version, but eager to hear others' thoughts on this.

cheers,

james
altE staff

for the turbine, the safe route is to go with standard factory issue.�  this will mesh with the manual, maintain any warranty, and have minimal user interaction required (assuming the replacement functions normally).

the other choice is as below
 go with a diversion load controller, like a tristar.�  this would need to be coupled with an appropriate sized diversion load.�  in this configuration, the turbine goes straight to the battery bank, and the diversion load controller closes the circuit to a diversion load when the battery bank reaches a certain voltage setpoint.�  this would require getting the setpoints correct for your battery bank.�  often two diversion load controllers are set up in parallel in case of the failure of one of them.

i was looking for something else and saw this:
http://www.blueskyenergyinc.com/news/article/announcing_the_sb3024i_il_duo-option/

now i am aware of a controller that does both.�  as far as i know, your 48v setup excludes you from this possibility regarding your earlier post.

bergey's controller for the xl.1 i think can handle up to .8 or 1kw of pv, but it is only for 24v nominal systems eliminating your request on both counts.

regarding the controller for the pv array, it depends on the array, the features you want, and the budget.�  there are tons of charge controller choices out there.�  if you can swing it, an mppt controller will give better performance.

the reason i said that each would perform better with a separate controller, is the same concept as you would see with a component stereo for example.�  a boom box may function, but not like the component system would.�  with 2 things in the same basket, some things are compromised.�  generally those controllers having a diversion element like the swwp or the bergey have a diversion load as a part of them and in the case of a bergey, a pwm controller for pv if you choose to use it.�  going separate enables an mppt controller to get better performance from the pv.�  if you go 2 in one, if your everything controller breaks, you have nothing but twice the problem.�  both controllers are also in an environment that could be hot by the nature of the diversion load, and cooler electronics are happier electronics.

thanks for the post, hope that helps, good luck with the system

james
altE staff

not that i am aware of.  you will likely get better performance putting them on separate controllers. 

james
altE staff

i would say that many solar folks have survived for decades with the old t105's, so if you miss some of the enhancements and new stickers on the new versions, for your first system, this is not a travesty. 

if this is a permanent installation on or in a building, spend your money on code compliant safety gear first, and second spend it on monitoring equipment so you learn from it.

good luck, please feel free to use the forum or the gallery for system advice from the contributors

james
altE staff

not sure if i am the jc

here are the factors we use

system efficiency (losses, ie inverter), depth of discharge, days of autonomy, temperature compensation.

depending on depth of discharge, system efficiency, and coolest anticipated battery bank temperature, that number seems reasonable, and perhaps on the lower side.

james
altE staff

here is the link to the newest version of pv and nec code, suggested practices. 

#6 bare copper with lay in lugs or split bolt lugs is commonly used in pv source circuits to a combiner or pass thru box, and after a combiner or pass thru the same size conductor as the largest current carrying conductor is typically used.

http://howto.altestore.com/Reference-Materials/National-Electric-Code-and-Solar-Electric-Systems/a45/

james,
altE staff

the voltage drop totally depends on the system and on the voltage it is wired for.  I would bet that your 2.5kw system will not have any advantage by inverting it first if you are running a straight grid tie setup.  likely your voltage will be well over 240vdc, making the dc run the more preferable one to make at length.

in order for somebody to do the calcs, they will need to know the array, and as close to the exact distance as possible.  I would imagine, that the wires would be large, but not necessarily outrageous.  the other bit of info that would be useful to your solar pro and/or your electrician would be what size your main service panel is rated for and if you have room for a backfeeding circuit breaker.

james
altE staff

the new breeze demo units (cut away) are non functioning.  if you mean the kit for a regular airx and air breeze, i am not aware of anyone trying it on a demo unit.  i am not sure if everything would be the same.

james
altE staff

hello,

all the prior posts are assuming a grid tie system WITHOUT any batteries.  systems with batteries are a different can of worms.

as far as inverter calculating for straight grid tie inverters, it just outputs what it can, no calculations.  the grid is always there running all loads that are not offset by the solar production.

james
altE staff

900?

http://www.altestore.com/store/Inverters/Off-Grid-Inverter/1000-to-1999-Watts/Xantrex-TR1512-120-60-InverterCharger/p6671/

which model were you looking for?

james
altE staff

no,

for straight grid tie inverters, the following is true.

the inverter only supplies solar energy when it is available from the solar array, and the grid is up and running normally.

the electric company (grid) supplies all the energy not supplied by solar, including at night.

james
altE staff

i dont understand your question, but this may help.

grid supplies main panel, when sunny inverter also supplies main panel reducing demand for electricity from grid.

if more electricity is coming from inverter than main panel demands at any instant, the excess is sold back to the electric company.

if 10 minutes after that instant, the loads get to be larger than what the inverter is putting out, the grid was always there and is supplying the difference.

the grid tie system generally offsets what is pulled from the grid when weather conditions allow.

hope that helps,

james
altE staff

huh, what are you running, an exeltech?  i know they have inverters that can run at that voltage.  the reason there are not more high voltage battery systems is that the code prevents banks beyond 48v nominal in residential systems.

so if you do have a 120v nominal array, i dont know of any controllers, but solar converters does do customer gear.  the problem as i understand is that the internal components cant handle those voltages, specifically the FETs i think.  you are looking at 2oo volts open circuit before temp derations, so that may mean no go for a controller like that, but i dont know, it is pushing the boundaries of my knowledge.

james
altE staff

without more detail, it is hard to say.  either is a nice controller.  without knowing the application (which is key) i can tell you two of the basic differences between them.

1. the xantrex mppt has an integrated ground fault protection device.  this is a nice feature, but it confuses many folks just starting out.  ground fault protection devices are a fire prevention and safety mechanism that senses current on the equipment grounding circuit, and opens the circuit, taking the ungrounded conductor with it.  in most off grid systems, this is accomplished with a circuit breaker combo that would be located in the dc load center.  if you go with an all xw system, all the manuals will sync, and you will be fine.  if you dont, all other wiring diagrams will assume an external gfp, and this confuses many folks in their wiring.  the xantrex internal gfp can be the only bond of grounded and equipment grounding conductors in the system.

2.  the xantrex includes a battery temperature sensor, while the outback is a sold separate add on of around 20 bucks.

minor differences

the xantrex uses only a heat sink for cooling, while the outback uses heat fins and a fan.  the 2nd gen outbacks (flexmax) are updated based on the feedback from the first unit regarding fan placement.

the outback is a little roomier in the wiring compartment than the xantrex is.  there is a partition in the xantrex for the xanbus network cable to the xw that can be frustrating when wiring.

like i said above, both controllers a very nice, it is a matter of preference.  we have both in our hq office right now.  if you are going to integrate an inverter by either manufacturer, then usually we see folks select the same brand charge controller for communication network benefits.

let the forum know what you are up to (loads list, array, potential array growth) and i am sure folks will chime in with opinions.

james
altE staff

this is a good thread.  I hear about this all the time.  here are the main points i try to stress to folks

read the manual. seriously. 

  if you intend to use the inverter in a portable manner, then one with plugs is likely fine.

if you intend on having a permanent installation wired to a main service panel, select a "hardwire" inverter preferably listed to UL standard 1741 for renewable energy applications.  follow the NEC and use disconnects and overcurrent protection where necessary, and use conduit to keep prying hands out of places they dont belong.

also, for those implementing a hardwire inverter to an existing building that was wired for AC, make sure there are no multiwire branch circuits in the wiring.  when only providing a 120v source from an inverter, this may cause the neutral to be overloaded.

you may see inverters listed to the UL standard 458.  to the best of my knowledge, this is for mobile applications like recreational vehicles and boats.

hope that helps,

james
altE staff

without batteries, a grid tie system will not run if the grid is down, it is important to point out.  grid tie systems are very strictly regulated, and must adhere to the national electric code, be inspected, and have the appropriate interconnection agreement with the utility in question.

james
altE staff

hmm, check with a company called solar converters, they do custom stuff. 

the bigger question is do you have a 120v nominal pv array?

james
altE staff

the xantrex power pack is not really designed to be used as a permanent system.  for that reason i would not try to hook up outside batteries to a powerpack. 

the nabcep entry level certificate of knowledge is waaaaaaay different from the pv installer certification.

to have taken the nabcep entry level certificate test and passed it does not make that person nabcep certified.

you can find more info on nabcep here.

http://www.nabcep.org/certificates/entry-level-certificate-program

http://www.nabcep.org/certification/pv-installer-certification

as for the battery, i would not try to rig up an outside battery to a portable powerpack, and when deciding on a permanent battery bank, i would not splurge on the first try.  surrette makes great batterys, folks new to off grid generally are not kind to their first battery bank.  i would suggest inexpensive golf cart batteries for starters.

james
altE staff

yes, you do have a 12v nominal module.�  notice the 36 cells in series, 17vmp, and 21 voc.

no, you dont have to have a 12v system.�  you may wire your array and or battery bank in several different ways.

no, i would not recommend using expensive surrettes as your first RE battery bank.�  they are fantastic batteries, but as many teens get a "beater" car for their first ride, i often suggest that folks get simple local golf cart batteries for their first endeavor, and spend the money they save on better battery monitoring and safety gear, and still come out ahead.

yes, mike holt publishes great stuff, however, last i checked, he does not make a guide that covers article 690 (pv).�  i currently keep understanding the nec volume 1, and illustrated guide to raceway and junction box calcs on my desk.

as for the code, i would recommend picking up the nec handbook, (the light blue hardcover), as this version has illustrations, photos, and notes that better explain the cryptic code speak.

i agree with mr schmidt, a subscription to home power would be good, and if they still offer it, get the upgrade with the dvd of every issue ever.�  i would start at 1999, and read one issue every few days until you get to the present.

finish your loads list, and come up with a number for watt hours per day.�  then we can give you more concrete help.�  if possible, use a kill a watt meter instead of guessing.

http://www.altestore.com/store/calculators/load_calculator/

if your pants are that on fire to get in the industry check on classes that offer the nabcep entry level certificate of knowledge test.�  employers often use this as a benchmark of interest and dedication when screening applicants.�  we have classes here, but there are other places as well such as sei, real goods, mrea, and more that offer quality training.

http://workshops.altestore.com/

good luck,

james
altE staff

if you are just getting started:

for free info, forum is good, but i would just take my time and read articles and watch videos in the university section.�  there are tons of free articles for those patient enough to read and absorb it.


keep reading and learning BEFORE buying if at all possible.

i would also suggest this book for those starting and wanting a practical guide.� 

http://www.altestore.com/store/Books-Classes-Educational-Videos/Solar-Electric-and-Passive-Solar/Photovoltaics-Design-Install-Manual/p481/

james
altE staff
 

read this,

http://howto.altestore.com/Articles-on-Renewable-Energy/Solar-Panel-System-or-PV-Systems/Solar-Panels-PV/Solar-Panels-PV-and-Voltages/a98/

let us know if you have any questions after.

you are going to need to know what you are trying to do, and you will have to do a loads list to define your needs.

james
altE staff

if not connected to a battery, the output of your charge controller would not likely read anything.

also with no battery connected, but the pv connected, you may have damaged your charge controller.  check the manuals provided for the equipment you are using.

cheers,

james
altE staff

ahh, you ruined my general response with a specific outlier.  I should know better than to assume. 

two mppt controllers would work in parallel. each connected to its own pv, serving same battery.
 
two of the circ pumps can work from one pv source (assuming enough power).

what i dont know is how one pv direct pump and one mppt controller would work together tied to the same module.  that i have not tried, nor had anyone i knew when i asked.

i understand what you are saying with the pv direct setup, but being that (if you do mean a laing) you are hitting it with a pv sledgehammer of 4x its required wattage, the battery would likely have the same affect in terms of run speed(excepting the obvious absence of daylight at night).  the running at night issue can be resolved with a dc timer or switch if you wanted to run everything off the battery baseline.

anyone out there tried what alice is after?

good luck,

james
altE staff

if i understand you correctly, you are trying to run a load from an mppt charge controller without a battery in the system?

i dont think that will work.  the controller will need to see a battery, and the battery should be wired in before the pv.

once you put the battery in, you can put run the pump off of it with a switch or dc timer, and the same for the unknown variable load. 

james
altE staff

from the module to the controller, 10awg (4mm^2) or 12awg wire should do fine.

the wires from the battery and inverter will depend on the size of the inverter. 

james
altE staff

perfect!

i never would have guessed that one.�  i would argue that foreign modules from buoys dont count for guess that module, but perhaps i am just a sore loser.

the first photo is all that i needed.�  if you count all the little rectangles you will get 36.�  36 cells in series = 12v nominal.

based on size that is likely between a 10 and 20 watt module when it was new.

that would mean that a relatively simple small controller should work fine for you.

here are some expamples.

http://store.altestore.com/Charge-Controllers/Solar-Charge-Controllers/Pwm-Type-Solar-Charge-Contollers/Morningstar-Charge-Controllers-Pwm/Morningstar-Sunguard-45A-12V-Pwm-Charge-Cntrlr/p793/

http://store.altestore.com/Charge-Controllers/Solar-Charge-Controllers/Pwm-Type-Solar-Charge-Contollers/Steca-Solar-Charge-ControllersPwm-Type/Steca-Solsum-6A-1224V-Charge-Controller/p1537/

http://store.altestore.com/Charge-Controllers/Solar-Charge-Controllers/Pwm-Type-Solar-Charge-Contollers/Morningstar-Charge-Controllers-Pwm/Morningstar-Sunsaver-Ss-6-6A-12V-Pwm-Charge-Cntrlr/p803/

http://store.altestore.com/Charge-Controllers/Solar-Charge-Controllers/Pwm-Shunt-Solar-Charge-Controllers/Specialty-Concepts-ASC-Charge-Controller/Specialty-Concepts-ASC-12V-4A-Solar-Charge-Controller/p1480/

good luck,

ask anything else if you need to.  - one other thing, when wiring a charge controller, always wire controller to battery first, then solar to controller.

james
altE staff