MX-60 question

Posted by Andy D on April 23, 2009, 07:16:00 PM

Re: MX-60 question (Reply #5)
Dave,

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 ??

I guess I don't understand HOW that would happen ?  Does the MX-60 do THAT much better with higher voltage ??  If so, all I can say is WOW !!  and THANKS Outback.

You've got me REALLY curious now.....I'm gonna run out tomorrow and slap two more panels on one array, and wire all 8 in pairs.....then compare it to the other array and see how it does.  ( I have two arrays of 6 panels each )

The tracker mounts are some homemade deals I welded up.

The are simple....a "H" frame of 1.5" square tubing, with the center part being a shaft of 2" steel, 4' long, mounted in two pillow block type bearings.  The bearings are bolted to the flat face of a pc of 8" x 2" steel channel.  The channel I welded to a 10' of 6" sch40 steel pipe, cut at a 37 degree angle. ( 1/2 way between summer/winter angles for here ) The pipe is anchored in a 4x4x4'block of poured concrete in the ground, with the sloped channel due south.

Then I welded 8' lengths of electrical Unistrut perpendicular to the "H" of square tubing that pivots east-west.  The panels mount to the Unistrut using standard cam nuts for it, and some aluminum "L" clips I had made at a local metal shop.  Ran self tapping screws thru the clips into the panel frames.

The tracking is done by a 36v DC linear actuator, with a controller built by a third party.....had a lot of trouble getting a controller to work, but believe I have that issue worked out now.  It active tracks the sun thru the day, then the panels park east at night for the next morning.
I had two controllers initially, one for each array....but now I've rigged a set of relays and one controller runs both actuators in tandem.....
 

Posted by David Ames on April 23, 2009, 09:52:00 PM

Re: MX-60 question (Reply #6)
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
 

Posted by Andy D on April 25, 2009, 01:13:12 AM

Re: MX-60 question (Reply #7)
andy,


 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.


Oh yeah, it was definitely a concrete truck day....actually it was also a concrete PUMP truck day.....since each of those took a bit over 2yds each and are located up on a hill above the house.....but I combined it with a pumped pour for a new root cellar roof ( 8x12 x 6" thick ) and some retainer wall block fill, so he pumped 10yds that day.


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.

Yeah, I'm a certified "farm welder".....as long as it doesn't leave the farm, it might hold....ahahahaaaa....

Nah, I do fair at it, though if it's something critical that has to hold pressure, I go get a buddy that really knows how to weld.  I have a Miller "Bobcat" stick welder.....engine driven 16hp 200amp model that also doubles as a backup generator ( 8kw ), then I also bought a Miller MIG wire welder a few years ago....that one makes even a 'farm welder' look like they know what they are doing !



 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.

MX-60 on one array....FX-60 ( what replaced the MX ) on the other.....I expanded once already and the MX was no longer available.

Don't know how I left you with the impression I'm off grid, because this is a grid tie system with battery backup....I have 8 --L-16's in backup....and plan to add 8 more, for a total of 1600 amp/hr....the first panels I installed were off grid for a bit while I experimented some....but then I got serious about the whole thing seeing what they would do.....

We DO have a nifty credit here.....TVA pays 15 cents/KwHr for all wind/solar up to 50kw sized system, then after it goes thru the buyback meter, we get to use that hour we produced for free IF I'm consuming electricity at the time ( which with a fridge and 3 freezers, something is always running here ), so that avoids buying that hour at 9.3cents to boot....pretty sweet deal I thought.  My goal is to get my system up to where it replaces about 1/2 what we actually use ( about 900kw/hr/month year round average )but replace ALL our bill due to the way the money works out. Then I'll quit and move on to another project.



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


My understanding with single axis trackers is you get about 30% more out of them ( and that seems to be holding true from what I see, playing with mine leaving one fixed in the "noon" position and letting the other one track ), but only gain 8% more on the other axis.  Since this was a "home built" deal, I decided to weld the up-down axis good and solid ( not knowing how wind would affect things.....getting a lot of "sail" area up there now )and just to make life simple.  Probably if I could come up with a good, solid, manual design to crank it up-down, I might...but I'm happy with this.  I have less than a 1000 bucks in each tracker, and that blows away the prices I see for active trackers this size...and I suspect my design is  a LOT more stout....I tend to way overbuild stuff.

BTW, we're coming up on our first "MEGA watt/hour".....1,000 KwHrs.....should happen tomorrow evening or the next morning based on these new panels I got up today......we went "online" end of December 08 for buyback purposes.....it's been doing 12-13kw/hrs a day lately, and now we're upping that by 6 panels ( 50% ), so we should be cranking out 18 or so per sunny day....the fans never shut off in the inverters on a days like this...ahahahaaaa.....but that's ok....that waste heat isn't wasted....it's going into my greenhouse (solar gear room is on one end of it )......the tomatoes love it.

I'm not a big fan of waste.........especially when I paid so much to get it.....ahahahaaaaa

andy

 

Posted by David Ames on April 25, 2009, 11:27:45 AM

Re: MX-60 question (Reply #8)
 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
 
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