David Ames's posts

 hello ron,

 looking at the battery calculations. it seems you did a nice job at trying to figure out your needed power for your loads. two days is a bit of a close margin though.

 things get a little sketchy with your pv numbers?

 the first thing we need to find out is do you have a 600 watt pv array? could be even more depending on your location! we need to get at least 2.4kwhs back into that bank every day.

kind regards, dave

"someone told me a telco fan assembly housing has a small 81 degree�  and 105 degree themostat for 48 volt d.c"

 looks like you may be on to something there.

here was another possible option.. a sealed thermal switch.

 http://catalog.selcoproducts.com/item/automatic-reset/matic-reset-1-2-disc-thermostats-close-on-risebkup/ca-100?&seo=110

-also carries a dc rating.
http://www.selcoproducts.com/faq.php

do let us know how you make out.

kind regards, dave

 hi eric,

 pickins' sure are slim in the 48 vdc thermostat department.

 this would fall into the same category of "i can't reccomend you do this but if it were me" advice.

 you may still be able to get your hands on one of those old mercury bulb thermostats to do the trick. i bet with such low currents you would be good just off the mercury switch contacts without any relay. many of those "honeywell" style thermostats had a hot/cold lever to change from a normally open to a normally closed switch. or you might be able to change the mounting position of the unit on the wall to change it from n/o to n/c.

 with any solution you come up with we should mention putting a small fuse in line here at the battery output to  keep things safe.

best regards, dave

 nice to hear dean. must have been lunch break at the shop.
good eyes on that one.

cheers, dave

 cool trick indeed using the internal shunt to read pv current. neat, thanks for that one.

 so much for the easy fix on this one..when you set up the one module test it takes the mis-matched problem out of play as well.

 i'm sure tech support went through the issues with the dip switch settings.(page 9 of manual)
http://www.altestore.com/mmsolar/others/Manual_BSE_SB2000E.pdf

 with temp sensor all four are on.(to the right)
without the temp sensor 1&2 are on 3&4 are off

do we have any flashing codes? also have you tried putting a good load on the bank while the sb2000 is running? (trying to run)

there are some issues with the setpoints for this controller needing a "voltage calibration tool" for banks that are not fully charged when trying to set the setpoints.

http://www.altestore.com/store/Charge-Controllers/Temperature-Sensors/Blue-Sky-Charge-Voltage-Calibration-Tool/p4068/?nav=detail-addon

 dean, might be worth one more try at powering down, go over all the wiring again and power back up-controller to battery first then add the pv input to the controller.

cheers, dave

hi dean,

 yes there are issues with mis-matched modules but your comment here raises a flag.

 "You can jump the positive from the PV over to the positive on battery and see you have 13 amps but when connected through the mppt it shows 2.8"

 sounds like you may have the pv- going to the battery bank. on this controller the pv- and bat- have to be keep seperate at the controller.

good luck, dave

 hello mr. miles,

 cheers on getting that water heater back on line. my efforts have been very limited working with these systems. but it looks like there is little that can go wrong with those closed loop drainback systems (sounds like what you have).
 
http://www.homepower.com/basics/hotwater/

 with the proper sized pump it should be like you said plug it in and "away it goes".

 the only things i can think of would be either an undersized pump or the crazy chance that we somehow have the pump direction of flow reversed. should be from reservoir to panel.

 we have some folks that come around the forum from time to time that do this for a living. hopefully they might pop by to help nail the trouble down.

best of luck, dave

here is product that may prove of interest to some.

http://www.bettergeneration.com/

they are calling it the "power predictor". it has an onboard anemometer and pv sensor that records to a data logger and is installed at the proposed site.

looks cool. i'm hoping to get one sent across the pond for evaluation.

it looks like there may be issues to accessing the logged
data without using the companys services? i won't know until i get one i guess.

regards, dave

hi mr. jacobson,

 congratulations on getting your system ready for first light! this is that cabin system in maine?

 i'm sure you have seen the battle cry of "keep the parallel strings to two or three max" and good advice it is.

 when we start to get into many parallel strings balance issues become a huge factor* and can doom a system to failure if we try to set it up in a conventional way.

 your system with "only" four strings and that exeltech 24v 1100w inverter should do just fine with the traditional series/parallel connections at the bank then up through a breaker** to the inverter. we will only be pulling about 50amps full throttle. i question the recommendation by exeltech on that 6awg wire. you won't regret going oversize with all the battery connections and inverter wiring here.

 also, i would shuffle the batteries in the bank once a year or so with this setup.

 if this is to be our final system size with no other loads, all grouped together in the same area and i had to pick a wire size i might go with 2awg for all battery and inverter wiring.

*some info about problems running parallel strings and what we can do to correct for it.

http://www.smartgauge.co.uk/batt_con.html

**a good breaker choice.

http://www.altestore.com/store/Enclosures-Electrical-and-Safety/Overcurrent-Devices-Fuses-Breakers/Circuit-Breakers/Outback-Obdc-70-70A-DC-Breaker/p883/

 some info here if you wish to explore the options of running parallel strings to a central busbar.

 a nice setup and writeup here.
http://www.wagonmaker.com/newbatt.html

 heres a pic of a totally non code dc combiner i set up with 10 parallel batteries in five strings of two at 12v. i routinely source 500amps from this buss.
http://www.sendspace.com/file/atqr2w

sounding good there james.
kind regards, dave

edit: method 4 on that smartgauge link looks like a winner here. this is a new addition since last i looked.

"Anybody else have this problem with a Trace C-60 charge controller?"

 no i have not nor do i know anyone else who has.


edit: i have removed a long winded comment here.

 
mr. key,

 thank you for that cert # and it looks like we can trace those modules back to that factory.

 i would have wagered that your initial post was a spambot. so sorry to have been such a pessimist about the rating.

 i wish you every success in your new endeavour. if there is a chance to have some input with your china supplier i would suggest that you advise them to do a total rework of their web page. and not use phrases like "warranty good if wires drop off"..gotta love some of those Chinese web pages!

 as to the merging of UL and IEC ratings.  "the winds of change they are a blowin." if i'm following this right..it looks like a move in the right direction. sure will be nice to be able to see any rating and know you are good to go.

kind regards, dave

 hello bobby key,

 i checked out your website. not a whole lot of info there. could not find much on innovosolar either? can you point me to where i can see that UL listing for those modules?

 are you aware that the folks who make this forum possible are dealers of photovoltaic modules as well as other RE products. it's how they earn their living. i'm surprised that competitors "ads" even stay on the board. not sure if i could be so at ease with it. so cheers to AltE.

 so bobby you may have a great company there and those innovosolar modules could be the best thing to come down the pike but i gotta call you on that ul thingy.

best regards, dave

 eric: thanks for sharing that project page you put together. nice job documenting the progress. quite the cast of characters helping with the build- everyone brings a little something to the table. nice to see. that view is fantastic! you are truly in GODS country there. nice touch with that automatic game camera, they have come a long way in the last few years. maybe you could put a ham on a chain and set up a bear powered generator!

kind regards, dave

 
thanks for keeping us updated on your repeater project. seeing this one through looks like your goal and anything less is not an option. cheers on that sir!

 this was never an easy project from the onset and your glycol "solution" to storing enough btu's to maintain operating temps is sure to work!

 have you worked up any estimates of tank size needed, exposure area/r-values and the like?

good fight. best regards, dave

 
hi there janet,

 sounds like things are running nicely on the charging side of your system.

 it's hard to guess exactly what your setup is. looks like about a 1.5kw pv array and producing/using about 110-160ah @ 48 volts nominal. that should make our battery bank in the neighborhood of 600ah @ 48vdc? does that sound about right. that would be 12 of the 200ah 12v batteries or 24 of the 200ah 6v batteries?....these battery bank sizes are based on a ~%20 depth of discharge. (%80 remaining) some schools of thought go with a ~%50 battery discharge limit and work them harder and replace them more often. that might make the bank about 8 of the 200ah 12v batteries or aprox 16 of the 200ah 6v batteries.

 i think jon is right on with the with the initial start of the compressor being the culprit. but your description of it happening at night smells more like voltage "droop" or sag, in that it does not drop out during the day when the pv array is holding up our voltage?

 one of the causes of dc voltage droop, besides an undersized battery bank is the size and length of the inverter cables. it is well worth the small effort and added expense to oversize this connection as well as the lugs and other battery cables.

 one other thing we might look at is giving the fridge its own separate ac branch circuit.

 hopefully we can find out more of what your running. ie: battery type and size, inverter model, fridge/freezer make, other loads, battery/inverter cable size and length. any inverter alarm codes. and are we using a battery monitor?

 sorry for all the questions..these kinds of problems are sort of fun to have a stab at and i'm sure we will get other folks interested in the "cure" for this one.

hang in there!
kind regards, dave

good,.. just trying to spread some info on the topic.
have never noticed anyone doing any of that hard sell around here. they seem to have a more like a just answering peoples questions and showing different options approach.

 ken, now this is only my opinion. for you, with this application any type of controller you choose that is within the needed rating will do the job just fine.

 two 135 watt modules will give you in the neighborhood of 100ah charge per day into 12 volt battery bank(with only a 4.5hour full rated sun day) we most likely will get more in the summer with a good eye on parking places.

 i might consider a larger battery bank and smaller array.

-just my thoughts here and open for debate.

kind regards, dave

hi folks,

 first a plug for our hosts.. thanks AltE for providing this free forum for the community.

 because this is an exchange of ideas, opinions and hopefully a good tool for those looking for information on renewable energy,(these subject threads are searchable and archived for folks to reference for who knows how long) i see this thread could use some additional resources on the topic of these mppt controllers.

 there is  much written on the subject, but here is a link to a short 1000 word writeup on the subject from a respected guru of renewables with nothing to sell.

 and now let's here it for and from mr. richard perez!

http://www.sendspace.com/file/7sunr4

 the above file was copied without permission from the archives of homepower magazine.

http://www.homepower.com/home/

 ken: good approach here, trying to research things out first before making a choice.

 fred: have a closer look into mppt, even us old dogs can learn new tricks. you may find that this new(ish) technology leaves some of those other controllers in the stone age for certain applications. and is worth at least considering as an option

kind regards, dave

 hi andy,

 thanks for giving us the inside tour of your system build. your descriptions are very clear and give a nice visual of what you have done. you had mentioned earlier the "(pair of Outback GTFX2524's)" but i missed it, that is a sweet deal getting paid for the production AND then getting the matching kwh's for use..i can see the potential for people to play games with that deal though, i'm sure the TVA is watching. also i was not aware of the meager payback of the dual axis setup (when combined with active single) till now and have looked into it a bit and in fact you are correct, so thanks for the insight there.

 congrats on the first MEGAWATT, that is like when we used to roll the odometer over in the car and mark the occasion with a line in the road!

 also i've read about folks adding external fans to blow over those mx's when running full tilt, the fx model apparently has a more robust internal fan as part of the new controller design.

 at least now you know if things get slow "down on the farm" you could get into the tracker building business..as the market price for trackers like that is HUGE $ compared to the grand a pop you whipped them up for!

kind regards, dave kb1mzf

andy,

 "Am I understanding you are saying by connecting 3 pairs of panels in series, doubling the voltage, that my output on 6 panels would rise from 930-950w range to the 1200w range ??"

 yikes!, if only that were possible. sorry, that was for the (8x175) totals.

 sounds like some project building that tracker-hope you called for a pour with all that concrete..i once over estimated my ability to hand mix and it nearly did me in.

 cheers on welding those monsters up, learning that skill (welding) has moved up on my list of "things to do" and am looking for an easy wire feed mig to have around the shack.
i'm currently working on an axial flux build (based on hugh piggots three phase design) and enjoy trying to do a project %100 on my own.

 that sure is an impressive amount of pv you are running. are both arrays running with mx60's? i'm sure you have your reasons for not going with a grid tie. there are some locations that give you a feed in credit based on "avoided costs" and them sell it back to you at standard rate. you must be close to being self sufficient with your power needs with that set up, and after ponying up for pv one sure learns to respect the amount of power we use.

 andy, i'm curious if you have had any after thoughts on making those trackers with a fixed 37* angle? (vs manually adjustable).

 i'm off to play with a coil winder i'm trying to put together.

kind regards, dave

"With 1050 watts of panel installed ( 6 x 175 ), the MOST I've ever seen it put out is 950watts....and typically more like 930"

 andy, those outputs are fantastic. anyone would be happy with those numbers. i would love to hear more about that homemade tracker you knocked up. is it a clockwork drive or an active diode sensor drive? or maybe it's passive fluid driven?

 that 70 amp current adjustment is an unadvertised "gift" from the folks at outback to make use of the maximun recommended array in cool temps with low battery state of charge. and should not be transfered over to the input side of the controller. there are some wizards with these controllers who are doing it though- but we mere mortals should stay with the factory specs. you can talk with the design engineers over on the outback tech forum..some of these guys are even changing the mppt parking % and sweep rates throughout the seasons for max output. seems to be more of a game than a set it and forget it approach that the average joe might be able to handle. i have yet to be able to get through the menu without referring to the manual. and lately i need a pair of glasses to read the pages...next i will be needing glasses to find the manual!

 and good advice from james about getting a breaker/disconnect/ocpd between the controller and battery bank.

 are you using the data logger? i would be interested to hear about your new production totals after adding this %33 more modules while doubling the vmp of your array...should bring that 930-950 watt high up to 1235-1260 watts or better. not to shabby!

good luck, dave

hi andy,

 that is the perfect plan!
keep the same breakers and your "home run" (the wire run from combiner to breaker before controller) exactly the same as you have and you will be good to go.

 this new setup will be better in every way to what you are running now.

cheers, dave



edit: "keep the same breakers" this is for the pv combiner and pv disconnect.
 you may have to recheck what you are using for the output side of the controller. if you went with the #2 and the outback recommended 80 amp breaker you are set. with anything smaller, even a 60 or 63 amp breaker we may get some nuisance tripping on the rare occasion that we are able to drive the output to it's preset current limit set point:) (default is 60amps*)

*user adjustable to 70amps 

 dan,

 thanks for sharing your review of the "airbird" product you got stuck with. sounds like you got the bird alright, but you may have saved someone else that same fate and that may make you feel a little better.

 all may not be lost. if that pma is useable in any way, you may be able to do a complete tear down and rebuild it from the ground up. did you see any power production at all? have you spun that alternator up and taken any readings?

 we have learned a whole bunch of things of what not to do when building a wind turbine here already and this may turn into a great learning opportunity for you while you redesign your machine out of anything that may be of use from that one.

good luck, dave

 thanks james,

 i've been following mr. wiles code corner in homepower and this is where playing with pv systems stops being all fun and games (for me anyhow). but a necessary step to move closer to a possible career change. any extra information that may help in preparation would be appreciated.(303 with mr. laforge)

either via this forum or by email
dave edited @ sbcglobal.net
or with an appointment at your home base in hudson.

thanks and cheers, dave

edit: 5/2 removed valid email.

thanks ken.

sounds like the hardcover is the way to go for me. then keep it as a desk reference when done. (i think there is still a desk under here somewhere)!

cheers, dave

 hi folks,

 as a textbook requirement for a continuing education class i need to pick up a 2008 edition of the nec by nfpa. sounds simple enough, but when i looked into it there seems to be so many different versions! softcover, hardcover, looseleaf, tradepaper? has anyone worked with these code books? if so which one do you find best for ease of use? is there any difference in the content?

http://www.powells.com/cgi-bin/biblio?inkey=62-9780877657903-1

anyone know of better sources ($)?

thanks for any input, dave

 
there are quite a few battery state of charge charts floating around. and many of them fail to mention that they are for "at rest" battery voltages at normal temperatures and others still are just plain wrong..one of the best i have encountered was put together by one of our own forum regulars and posted on his ever growing blog. lots of good info there from solar to cornstoves to gardening.

http://solarjohn.blogspot.com/2007/03/measuring-battery-state-of-charge.html#links

 you may have seen in a previous post some folks were talking about checking the AH capacity of a battery and made reference to the 10.5 voltage? (a drawdown test)..this is a controlled test for capacity and when done we are ready with our charger to start the recovery of the battery as soon as the test is completed. we do not want to use that 10.5 volts as a cutoff on a regular basis (ever) and some inverters have a manual adjustment so we can set our LVD (low voltage disconnect) to some higher setting.

 your right of course that most inverters have it set at 10.5 volts, but don't forget that is under load and the actual value (at rest) will be higher.

 bottom line is 10.5 volts is a very bad place to be with a lead acid battery and should only be brought to that voltage under a watchful eye for testing or by blunder.. and a charge should begin ASAP if we ever get that low.

best regards, dave

 marc,

 a valid argument can be made against using an ac "only" type switch or even pull chain for this application. and for the purposes of this forum i agree that's not the right way..(the thinking was with such low currents it will not be a problem) but to do it "right" and for the record we should go with a rated switch. they go by the name of "snap switch" usually if they do not say ac only on them they are dual rated ac/dc. but to be sure we can get one that is expressly stated as being dc rated. heres some here.

http://www.advancedenergysolution.com/catalog/systemcomponents/switchs.htm#dc

 lots of good dc switches and plugs and such. follow the page links for dc switches.

 some interesting reading on the subject here.

http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/showpage.html?name=WJQR.GuideInfo&ccnshorttitle=Snap+Switches&objid=1074128100&cfgid=1073741824&version=versionless&parent_id=1073995251&sequence=1

kind regards, dave

 hi marc,

 you kind of had me there by using the words "cheap" and "solar power" in the same sentence. but i see you posted on the 30th so it was not some april fools joke.

 kidding aside, this will be a great way to get your feet wet with renewable energy. the problem is once you start playing around with these renewables and see what you are capable of you won't want to stop there!

 for a bare bones workable system we won't need much.

a cheap group 27 marine rated battery can be had for about $50ish dollars.

 a small pv module (that's not a toy) like this one.

 http://store.altestore.com/Solar-Panels/1-to-50-Watt-Solar-Panels/Power-Up-5W-12V-Solar-Panel/p1027/

 and a few 12vdc cfl's like these.

�  http://store.altestore.com/Lighting-Fans/Compact-Fluorescent/Phocos-CL1205W-12V-5W-Warm-CFL-Lamp/p1002/

 or these.

�  http://store.altestore.com/Lighting-Fans/Compact-Fluorescent/Steca-ESL11W-12V-Fluorescent-Lamp-Warm-White/p1526/

 add in some standard wiring and a few pull chain edison base lamp fixtures and you will be off to the races!

 with this size pv module and battery you can get away without any charge controller (staying within the accepted %2 standard) ie: group 27 battery is aprox 100ah X %2 = 2ah max for unregulated pv source. a 5watt module will max out at about 0.3amps- well within accepted practices even at double that. the module listed has nice 10 foot leads with a blocking diode built in.

 i would add an in line fuse here to the pv of an amp or two in the unlikely event of a diode failure in the shorted mode (very unlikely) as well as to the battery output (to the cfl's) if we use four of those 5watt cfl's and they are all on that's 5 X 4= 20watts/12volts=aprox 1.6amps those lamps have a slight startup surge so we might choose a 5amp fuse just to be safe in case we get a short somewhere.

 the expected output from the above setup should yield about 20 watt hours of power a day (at four hours of full rated sun) and be able to power all four of those 5watt cfl's seven hours each week, or two of them for 14 hours etc. we do want to try to get the module pointed perpendicular to the sun..just adjust it at around noon so you don't see a shadow around the frame and you should be good.

 comes to about $200 bucks, not cheap cheap but not soo bad...

 have fun, dave

edit: marc re-reading my post, i might add that it would be ok to go even a bit smaller with the battery..even somewhere around a 50ah trolling type battery would do the trick. i would not go much bigger than the 100ah though (here we run the risk of not being able to drive it to a full charge) my opinion only..find whats on sale.

 well..stephen this is just one guys opinion and hopefully we might get a few more for what they are worth. we can spent days weighing our options, crunching the numbers, and graphing the financials of our decision but in the end it all comes down to compromises. i think we both know that this is not the ideal setup we are proposing here.

 the ideal setup might be to have both modules in the same location and strung in series as a 24 volt array. or to run them on separate controllers with the modules fore and aft.

 but i believe in the end what you want to do will work and work fairly well. and considering the full time losses incurred trying to provide isolation of the modules from each other i would just let the kc130's bypass diodes do their job and let the controller sort out the rest.

 we would be doing a disservice to other forum readers if we did not mention the needed overcurrent protection for this setup and just for the convenience factor you can't beat a manual breaker of the proper rating. i might go with a 15amp breaker for each of the 12awg positive kc130 strings right near the controller then from the breakers to a combiner block then the short run with 4awg out to the controller input. the same with the 12awg negative but without the breakers. from the controller we might go with the same 4awg and a 25amp breaker then on to our battery bank. yep, a little overkill here with the 4awg and little underkill with the 25amp breaker. that's just me being over cautious. along those same lines we might consider trading that 12awg in for a 6awg or 8awg for the pv runs.(for voltage drop reasons not safety concerns).

best of luck to you...

...perhaps a few other folks might chime in to add their two cents worth.

kind regards, dave

 sounds like you are on the right track..just a note here, when wiring up a series set of modules with those mc techno-wacko connectors it's very easy to get the polarity of the modules mixed up. we may want to double check with our meter.