DIY Installed system near Joplin, Missouri

[stuman]

Here is my DIY system.  My signature describes the equipment.  I would like to modify the panel rack to allow for a summer angle of 0, but the 31.5 degree angle seems to be working quite well so far.  Highest single day's production was 21.5 Kwh with my battery's A/C unit running and a 15000 BTU unit for most of the day.  I am "grid connected", which is that the grid is my backup, but I do NOT feed/sell back to it.  This is an easy setup with the MagnaSine inverter/charger.

[zoneblue]

With the weight involved in an array like that when i pondered this here, i concluded the only way to have adjustable tilt, was a seesaw type arrangement with the pivot at dead center. Then youd either need to stiffent the rack to eradicate the flex, or brace it both sides. Or both! That would involve quite a rebuild of your rack! Is it worth it?

With regard your bluesea sealed breakers, i originally bought one of those and was told by the pros here that it was not suitable for use with an inverter. They dont have a high interupt rating, because theres no where for arc to go. And being thermal they are also slow. For about the same price get a carling from NAWs and sleep well at night.

[RossW]

With the weight involved in an array like that when i pondered this here, i concluded the only way to have adjustable tilt, was a seesaw type arrangement with the pivot at dead center. Then youd either need to stiffent the rack to eradicate the flex, or brace it both sides. Or both! That would involve quite a rebuild of your rack! Is it worth it?

Agree. That's what I did here with my small non-tracking array:


Because it's "perfectly" balanced (well, almost! I can tip it with one hand easily), it means the linear actuator has no trouble positioning the array.

[Westbranch]

Ross, forgive me for being blind &/or dumb, but what 'stiffens' the center axis of that array?  It seems to be non-continuous??
I do see the continuous rods on the outside edges.

12V actuator?

[dgd]

Ross,
That frame looks well engineered but why the actuator? Are you resetting the panel angle on a regular basis, perhaps every few days or a week?  I also can't help wondering about the cost of a substantial aluminum channel frame compared to the wood frame that stuman has.
I use a similar wood frame but the angled struts supporting the PV connect at top with coach bolts and the bottom ends with aluminum angle bracket that can be heightened/lowered to change angle from about 35 degrees to 10 degrees. The tops just rotate slightly in the bolts.
I only change this once a year but it is a two person task.

Stuman,
As you have the PVs in rows of 5 and lenghways mounted I cannot see how a simple angle adjustment could be achieved. Unless the PVs are really on angle bars in groups of three then it would be just a matter of brackets on bottom to lift each set of 3 and at tops perhaps use bolts via ali brackets to connect them to upper horizontal bar.

dgd

[RossW]

Ross, forgive me for being blind &/or dumb, but what 'stiffens' the center axis of that array?  It seems to be non-continuous??
I do see the continuous rods on the outside edges.

12V actuator?

The centre wasn't stiffened. I'd planned on joining the centre pipe, but in reality it simply hasn't been necessary.

Yes, it's a 12V actuator.

[RossW]

That frame looks well engineered but why the actuator? Are you resetting the panel angle on a regular basis, perhaps every few days or a week?  I also can't help wondering about the cost of a substantial aluminum channel frame compared to the wood frame that stuman has.
I use a similar wood frame but the angled struts supporting the PV connect at top with coach bolts and the bottom ends with aluminum angle bracket that can be heightened/lowered to change angle from about 35 degrees to 10 degrees. The tops just rotate slightly in the bolts.
I only change this once a year but it is a two person task.

Yes, the array angle is adjusted frequently. Ultimately, it will be controlled through the day to reduce the off-axis error somewhat.

The aluminium channel was actually not very expensive, was easier to work with, won't warp or be eaten by things, or catch fire, or need painting...

Do you only change it once a year (presumably actually TWICE a year!) *BECAUSE* it's a two person job?

[Westbranch]

Ross, how strong are the winds in your area? Is your array sited where it get exposed to them?

[stuman]

I built my rack on the cheap out of treated lumber.  It is pretty rock solid.  I've had straight line winds well over 50 without concern.  The gap between panels is to prevent it from becoming a single piece as far as wind is concerned...to let north wind through between them.  Normal winds around here are from the west or west-south-west.  It is rare to have strong winds from due north.  To the south, I have a hedge row that breaks the winds up before they get to me.  East winds are even more rare than north, and my house will break those up.  Panels are wired vertically...in three's...but since I'm planning on changing the angle of the array as a single unit, how they are wired is immaterial.  For just a little bit more wood, I can brace each vertical to itself as opposed to the supports I have on the poles at present.  A well balanced pivot would make moving it easily.  I will only move it twice a year...summer position and rest-of-the-year.  Long side poles would be hinged to allow them to "break" with locking mechanisms for each position.  Short end poles would have a similar arrangement added to them.  Center poles would be planted on which to place the pivot.  Or I just might build a new rack altogether just to the east of this one with center pivot designed in from the start.

As far as breakers go, I'm not done with them yet.  I'm almost always home and manually disconnect the array in bad lightning...the old breaker boxes at the far right in the equipment picture.  The other breakers are more for switches and absolute dead short protection.  On the to do list are some lightning arresters.   I even unplug from the grid from my MagnaSine during lightning storms as our grid power is far from stable around here...which is what got me started on this in the beginning.  Being able to continue my life without significant inconvenience in the event that the grid goes away is an ongoing motivation.  The grid could fail for an extended time (I've already seen three day outages) or the price could go up or my ability to pay could go down.  In any of these situations, I would not have to change my daily routine much at this point.

Also on the to do list is a generator...I can use my truck with a big inverter for emergency power right now (except the biggest working inverter I have is only 750 watt...bigger inverters in MSW are not expensive, and the MagnaSine is happy with that).  Planned is a propane powered unit with a 48 volt alternator to charge the batteries directly when used and the automatic generator start module add on for the inverter.  Additional battery capacity is on the wish list too.  Eventually, I want enough battery to cruise through the night without concern and an alternate fuel (biomass gasification) generator to use on cloudy days.  Such a generator will require manual running (biomass is fairly inconsistent).  if I have enough battery capacity it won't be needed that often.

So far, I'm extremely happy with how this is working out.  While still grid connected, my electric bill is staying well under $100, with the lowest I've had at $80.xx.  $30 of that is a "service availability" charge just for having the meter.  Before putting this system in place, my bill was almost always over $200 and over $300 in the summer...and I expect rates to skyrocket as the "carbon taxes" start to have effect.

[TomW]

I built my rack on the cheap out of treated lumber.  It is pretty rock solid.  I've had straight line winds well over 50 without concern.  The gap between panels is to prevent it from becoming a single piece as far as wind is concerned...

Stuman;

Not to be a  Debbie Downer but.

I am certainly no expert on aerodynamics but I recall reading once that a gap between panels to "let wind pass" can actually increase wind resistance and loading.

I forget where but the explanation made sense at the time and I do not recall the details.

Not sure I would be comfortable with wooden racks for several reasons like expansion and strength. People do seem to get away with it all the time, however.

Just tossing those on the pile.

Best of luck with it.

Tom

[dgd]

Yes, the array angle is adjusted frequently. Ultimately, it will be controlled through the day to reduce the off-axis error somewhat.

The aluminium channel was actually not very expensive, was easier to work with, won't warp or be eaten by things, or catch fire, or need painting...

Do you only change it once a year (presumably actually TWICE a year!) *BECAUSE* it's a two person job?

I've got lazy now and really don't bother changing the rack angle away from 30 degrees. Seems little sense in chasing every PV watt when from Oct to April my batteries are in float by midday.
The plan was to adjust two to six times a year, was easiest with 2 people but using a cross brace between two runners holding PVs I could easily lift lower end of runners upwards to reduce angle and slot in support bolts.

As for aluminium channel/angle it is easy to work with, cuts like hardwood etc. My treated lumber rack mounting is ok but I noticed as the wood dried out it has warped a bit but it is well braced so the PVs are all still aligned good.

dgd

[stuman]

Interesting.  I might change that later.  I'm considering relocating the whole rack to the east a bit as I redesign it to be tilt adjustable.  It would then be protected from north wind by my garage...and I would have no qualms about designing it with no gaps in between.  I can't see how having gaps would increase resistance...venetian blinds don't catch as much wind as a curtain.  It is pretty solid.  Both me and my neighbor were climbing all over it like a set of bleachers while building it.  I have all the bolts put in with plastic locking nuts and left a bit loose to allow for unequal expansion characteristics between the wood and aluminum frames.  "Movement" is not a problem, as long as they remain true in their plane.

I built my rack on the cheap out of treated lumber.  It is pretty rock solid.  I've had straight line winds well over 50 without concern.  The gap between panels is to prevent it from becoming a single piece as far as wind is concerned...

Stuman;

Not to be a  Debbie Downer but.

I am certainly no expert on aerodynamics but I recall reading once that a gap between panels to "let wind pass" can actually increase wind resistance and loading.

I forget where but the explanation made sense at the time and I do not recall the details.

Not sure I would be comfortable with wooden racks for several reasons like expansion and strength. People do seem to get away with it all the time, however.

Just tossing those on the pile.

Best of luck with it.

Tom

[toothy]

I seem to remember the same thing as Tom about spacing and loads from way back in the day. I have the same sort of rack as yours with the panels tight, they haven't blown away yet, not that yours will.

Wade

[stuman]

I'm going to steel three panels and put them on my RV.  At 3600 watts nominal, these panels can overload my Midnite 150, and have caused it to reset.  Reducing the input my 720 watts will prevent that from happening.  I'm getting another Midnite 150 for my RV so I can use it later to double up (follow me) when I get more panels for my home system...

RV is 12 volt system.

[Photowhit]

At 3600 watts nominal, these panels can overload my Midnite 150, and have caused it to reset...

At 48 volts a Midnite 150 should handle that, nicely. I think I can over panel my 24v array's to 2700 watts, Something doesn't click.

Your wooden mount looks well built, mine is a bit lighter built, though better protected, and has handled 60+mph straight line winds, though out of the south, without a problem.