Author Topic: Maxing out my small off-grid system  (Read 13594 times)

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DamonHD

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Maxing out my small off-grid system
« on: May 07, 2016, 12:45:52 PM »
Hi,

Adding more to my grid-tied PV system will now require tedious amounts of paperwork at the very least, and AC-coupled battery systems are still too expensive and lossy...

Ideally I hoping to beef up my small off-grid system to gather up to ~500Wh of extra energy every day mid-winter, which implies 500Wp of extra panels.  I don't mind 'wasting' some potential power mid-summer.  I believe that with some TLC and creativity my current system with its 400Ah x 12V lead-acid gel can possibly be extended to accommodate that and take some loads off-grid.  (A controller upgrade from my current SS-MPPT-15L may or may not have to happen amongst other things.)

So...  When I had the last part of my grid-tie system put in I had these spare rails put up:

http://gallery.hd.org/_c/mechanoids/_more2010/_more04/solar-PV-grid-tie-roof-mounted-power-additional-system-including-extensive-rewiring-and-upgrading-to-consumer-unit-to-accommodate-new-generation-safely-with-some-work-by-off-grid-solar-light-at-night-9-DHD.jpg.html

http://gallery.hd.org/_c/mechanoids/_more2010/_more04/solar-PV-grid-tie-roof-mounted-power-additional-system-including-extensive-rewiring-and-upgrading-to-consumer-unit-to-accommodate-new-generation-safely-with-some-work-by-off-grid-solar-light-at-night-60-DHD.jpg.html

http://gallery.hd.org/_c/mechanoids/_more2010/_more04/solar-PV-grid-tie-roof-mounted-power-additional-system-including-extensive-rewiring-and-upgrading-to-consumer-unit-to-accommodate-new-generation-safely-with-some-work-by-off-grid-solar-light-at-night-62-DHD.jpg.html

So about 34cm/13.5" rail centre to rail centre and about 3m/10' long in an ~1m gap.

I'd like to put a couple of 12V nominal panels up there in the first instance for easiest integration with my existing system, though higher voltages and a new controller might be fine.

My main issue is that I don't understand how the various fixing systems work, so what can be made to safely fit there.

Eg could I fit (and how) two of these up there:

http://www.bimblesolar.com/shanghai175w

or these?

http://www.bimblesolar.com/jasolar260w

Rgds

Damon
« Last Edit: May 07, 2016, 02:57:35 PM by DamonHD »

Mary B

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Re: Maxing out my small off-grid system
« Reply #1 on: May 07, 2016, 02:20:10 PM »
access denied on the pictures...

Mary B

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Re: Maxing out my small off-grid system
« Reply #2 on: May 07, 2016, 05:51:02 PM »
Working now!

DamonHD

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Re: Maxing out my small off-grid system
« Reply #3 on: May 19, 2016, 02:25:20 AM »
Still not understanding how to use the rails on the roof, but have been chewing the cud on generally expanding the off-grid system significantly.

http://www.earth.org.uk/LiFePO4-battery-testing-with-solar-PV-off-grid-system.html#2016exp

Upshot: if I want to collect ~0.5kWh/day off-grid in mid-winter I probably need to simplify the system to make better use of my very limited south-facing wall space.  That may mean taking my LiFePO4 battery out (I currently can't see how to keep it safely/simply/efficiently integrated), and chucking a couple of new 175W panels up in the prime spots, with the option to replace those with 300W+ panels later...

Rgds

Damon

PS. Any guidance on using the rails still welcome!


DamonHD

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Re: Maxing out my small off-grid system
« Reply #5 on: May 19, 2016, 10:39:51 AM »
Yes, that's a good way of looking at it, thank you!

(I'm now trying to get a salesman to do some real work and try to decide which if any of the fastenings he sells would work with the nice 300W panels he has...)

Thanks

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #6 on: May 29, 2016, 03:21:58 AM »
I have simplified things and taken out the LiFePO4 (LFP) battery ready for bigger rearrangements later.  I gave that LFP a 5-year test and I'd say it worked reasonably well.  The main complication was ensuring that enough energy ended up in the right batteries especially mid-winter.  In IT it's reasonably clear that partitioning resources too early or too much is unhelpful, as here.

I am working up to adding probably 2x260W* (vertical, bolted to our clear-ish south-facing garden wall space freeing up some patio space), feeding initially into my (200W nominal maximum SS-MPPT-15L, which is safe) as a 30Vmpp string, and moving most of the existing panels (12V nominal,  17--19Vmpp) on to a cheap PWM controller for the same bank (a few will probably be retired).  The aim is to keep filling the batteries nearly every day even in winter to be able to supply ~500Wh/d of loads; supplying more in summer is not important.

If it looks like lots of energy is being wasted then I may move the 12V string back to the SS-MPPT-15L and splash out on a new 40W/500W MPPT controller for the 30Vmpp string.

*Historically I have paid 2--4/Wp retail for PV, the panels I have my eye on are nominally ~0.40/Wp and there are lots at similar prices.  I could slightly increase output from my limited space with 315Wp panels the same size but they are 0.70--1 per Wp, so too spendy for now.

Rgds

Damon

PS. Found a bunch of fittings in my shed probably for those roof rails, but I still have no real idea how to best use them, given the hazards.



« Last Edit: May 29, 2016, 03:26:37 AM by DamonHD »

Harold in CR

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Re: Maxing out my small off-grid system
« Reply #7 on: May 29, 2016, 06:09:36 AM »

 Maybe post a photo of those fittings and a drawing of what you want to do. Mainly, you need to tighten the panels to that rail with pull down clips. The bolt head part, with the wide square washer will slide inside the turned edges of the rail.

 Maybe I'm not sure just what your plans are ??

DamonHD

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Re: Maxing out my small off-grid system
« Reply #8 on: May 29, 2016, 06:38:49 AM »
I'm not sure what my plans are either: I've attempted to write up a bit more clearly here:

http://www.earth.org.uk/expanding-off-grid-PV-system.html

I will take a picture of some of those fittings and post later!

I suspect that if I buy one more of the 1.6m x 1m (30Vmpp) panels that I'm proposing to put on the vertical wall then it could be easily put on those rails, getting me to not far off 1kWp off-grid, though with all sorts of funny behaviour!

Rgds

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #9 on: May 29, 2016, 01:16:04 PM »
Looks like I have Unirac Solarmount or similar, including 8 C-clamps:

http://gallery.hd.org/_c/mechanoids/_more2016/_more05/solar-PV-panel-racking-metal-fixings-fastenings-for-roof-9-DHD.jpg.html

though I would probably need "D" clamps for the 40mm panel I am hoping to put up.

Now I have to find someone prepared to sell me a handful I suppose, or are these "slightly too short" ones likely to be effective and safe (don't want it falling off on someone's head)?

Rgds

Damon

clockmanFRA

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Re: Maxing out my small off-grid system
« Reply #10 on: May 29, 2016, 02:37:15 PM »
Heres UK stuff.

I have a static array, 11off, 250W, 37.8v VOC, one string to a SMA SB3000 GTI. Re-configured for my OzInverter.

There good quality panels but different height/size frames. As you can see from the following pics the different panel clip arrangements especially with my assorted frame sizes. I get bigger frame size clips than I need then i cut the foot away to size and run a thread dia down the bolt a bit and cut the excess bolt away, simples.!

That's a Fisher rail but its no longer used but the clamping through the top is the main clamps on all rails.

Nowadays the brackets from the roof to the rails are vertical and clamp to the back of the rail with serrations, there's a few different types.

With number 2 pic the foot of the clamp is just to short for that thickness of panel, so a new one was fitted.
These were photographed because the clamping was poor, so ensure the clamps are for the correct height of panel frames.....

Trust this helps?


« Last Edit: May 29, 2016, 02:41:58 PM by clockmanFRA »
Everything is possible, just give me time.

OzInverter man. Normandy France.

3off Hugh P's 3.7m Wind T's (9 years).  .. 5kW PV on 3 Trackers, (5 yrs) .. 9kW PV AC coupled Used/SH GTI's, on my OzInverter created Grid, and back charging with AC Coupling to the OzInverter to my 48v 1300ah batteries.

DamonHD

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Re: Maxing out my small off-grid system
« Reply #11 on: May 30, 2016, 12:25:40 AM »
Hi,

Thanks!

Looks like I need to get myself the correct height clamps then...

Also, it seems that to bold the panel(s) horizontally to the rails in their odd configuration I'll need to drill new holes in the short edges of the frame, but maybe I've misunderstood?

Rgds

Damon

clockmanFRA

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Re: Maxing out my small off-grid system
« Reply #12 on: May 30, 2016, 03:01:57 AM »
You shouldn't need to drill the panel frames.

However, with my Solar Trackers I used this arrangement, as the panels get a lot of stress, and the metal frame is an integral part of the overall structure. But drilling through the side of these Sharpe seconds the frame is double laminated so silicone is required in the bolt hole.

The previous photos were not so good clamps, these are how things should be.

Here is a couple of 250W panels and you can see how the clamps should work with the correct size of clamp to match the panel frame height. There are mid way clamps and end clamps.

Photo of bits on the floor are for the GRASOL PV rail system. Brackets bolts etc are either Stainless steel or aluminium. I will not buy the PV panel frame clamps until I have the PV panels themselves, then I know the real thickness of the frames. I look out for good deals on PV panels.
 
Just re-roofing at present on a south facing, installing those GRASOL brackets and PV rails for a 5kW installation. But will do 2off SMA SB2500 GTI's on this roof.

Most PV retail companies will sell you the PV clamps, but they do need to know the rail manufacturer.
I used to get clamps from these guys, but do not mention my name.!!!!

http://www.navitron.org.uk/store/solar-panels/pv-roof-mounting I think they post.....

I trust this helps?
Everything is possible, just give me time.

OzInverter man. Normandy France.

3off Hugh P's 3.7m Wind T's (9 years).  .. 5kW PV on 3 Trackers, (5 yrs) .. 9kW PV AC coupled Used/SH GTI's, on my OzInverter created Grid, and back charging with AC Coupling to the OzInverter to my 48v 1300ah batteries.

DamonHD

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Re: Maxing out my small off-grid system
« Reply #13 on: May 30, 2016, 03:10:14 AM »
Ah, I'm assuming that I have to bolt the panel onto the rack also, else what's to stop it slipping out from under the clamps, eg on a particularly cold/hot/windy day, and falling on my head?  Are the panels really held by just the clamps?  Makes me nervous!

Rgds

Damon

clockmanFRA

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Re: Maxing out my small off-grid system
« Reply #14 on: May 30, 2016, 03:43:47 AM »
Eight years ago I felt nervous like that.

But I experimented with the standard industry clamps, and yes they do hold incredibly well on the correct aluminium rails.

Those black panels of mine on the static array haven't moved, I even tested a couple with just 2 clamps holding for a month or two, they did the job.

But if you are going to mount some vertically on a wall ?
Everything is possible, just give me time.

OzInverter man. Normandy France.

3off Hugh P's 3.7m Wind T's (9 years).  .. 5kW PV on 3 Trackers, (5 yrs) .. 9kW PV AC coupled Used/SH GTI's, on my OzInverter created Grid, and back charging with AC Coupling to the OzInverter to my 48v 1300ah batteries.

DamonHD

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Re: Maxing out my small off-grid system
« Reply #15 on: May 30, 2016, 06:19:39 AM »
I will do the vertical panels with brackets:

http://www.bimblesolar.com/extras/mounting/aluminium-mounts

I've ordered a set to try out.

They can't do as much damage if they fall: possibly a crushed tomato plant!

Rgds

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #16 on: May 30, 2016, 02:19:32 PM »
Thanks for all the help so far: I feel nearly educated.

I have a no-name 100Wp panel that looks like it would work with the clamps that I already have, and the only issue remaining that I can see is that I would have to clamp it on its short sides, which is apparently frowned upon for some panels (because of the greater flexing along the long axis).  I cannot see any particular structural differences on the long and short axes on this particular panel that would make the problem worse.

Rgds

Damon

Frank S

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Re: Maxing out my small off-grid system
« Reply #17 on: May 30, 2016, 09:56:09 PM »
my array has been through some 60 to 75 MPH winds several times in the past 3 years. I made my own brackets and mounting frame the one thing I did to help the clamping force was to put fiber pads under the panels at the clamps My clamps were made from .050" ( about 1.3 mm)aluminum sheet sheared on a HF. guillotine shear and formed on a hand made break.
The mounting frame is made out of 1 1/2" 16 ga. sq. tube and 1.94" 16 ga. round tube
 
I live so far outside of the box, when I die they will stretch my carcass over the coffin

DamonHD

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Re: Maxing out my small off-grid system
« Reply #18 on: May 31, 2016, 02:30:06 AM »
Interesting, thanks.

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #19 on: June 11, 2016, 05:16:39 AM »
@clockmanFRA, Harold, Frank: thanks.

It looks like my 100W panel should work with the clips that I have, and I'll try to get it up on the rails when I have some guttering work done!

Hurrah.

Rgds

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #20 on: June 11, 2016, 12:24:12 PM »
Did some re-arranging and tidying (and shortening) of the cabling, and added a new cable segment to be able to run both strings (as will be 17Vmp and 30Vmp nominal) directly to controllers near to the battery bank.

Everything is still combined into a single ~17Vmp input at the SS-MPPT-15L for the moment.

Rgds

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #21 on: June 16, 2016, 12:29:41 AM »
Ha, finally got Ki-CAD running on my Mac, alongside Eagle, and got someone to hold my hand long enough to understand how you use it and drew up (badly) the super-simple off-grid system layout ready to whack in all the new complications as I add the new big panels!



Rgds

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #22 on: June 25, 2016, 03:54:10 AM »
Hmm, got sent the wrong solar controller yesterday by my supplier.  This is where I would be had the right one been sent!



The controller is cheap because it's possible that this arrangement works badly or I feel spendy and splash out for a grown-up MPPT controller in a different arrangement, or even swap out all my LA for LFP or whatever, but probably not for at least 6 months...

Rgds

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #23 on: June 29, 2016, 04:30:42 AM »
Installed the new PWM controller today.  Because I'm trying to keep costs down I'm taking a few short-cuts at least for now:

http://www.earth.org.uk/expanding-off-grid-PV-system.html#20160629

In particular...  Bank attachment points: the battery connections for the new controller land on opposite corners of the bank, but the two other corners from the MPPT controller. This is a little controversial but is in the end expected to be a minority of the charge input and not a power drain point.

Rgds

Damon

DamonHD

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Re: Maxing out my small off-grid system
« Reply #24 on: July 22, 2016, 09:27:57 AM »
So the big panels arrived along with all the other bits and pieces, with a couple of last-minute excitements:

http://www.earth.org.uk/expanding-off-grid-PV-system.html#20160722

In particular the original JA panels were eventually substituted with Canadian Solar CS6P-255P panels.

The Al brackets I ordered seem not to work with the CS panels (slot too short):

9882-0

And the positioning of the mounting holes along the edges is not as good for me as the JA panels as I have to mount this vertically on a wall and the furthest down from the 'top' edge might be above the top of the wall!

So I am faced with possibly drilling new mounting holes, which worries me somewhat.

Is it a stupid idea?  If not, how best should I do it?  I don't have a workshop but I do have some hand tools.

Rgds

Damon

Harold in CR

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Re: Maxing out my small off-grid system
« Reply #25 on: July 22, 2016, 12:56:38 PM »

 I would mark and drill new holes.  Aluminum drills easy, so, make sure you have a way to stop it from going through the hole and damaging the panel itself. I have drill collars for stopping bits from going too deep.

 A DIY would be a small fuel line clamp. Place it on the bit so it just goes through the frame and can not go any deeper. Check after each hole, to be sure the clamp doesn't ride up the bit, which COULD happen.

DamonHD

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Re: Maxing out my small off-grid system
« Reply #26 on: July 22, 2016, 01:05:21 PM »
Thanks!

Just use an ordinary 'masonry' drill bit?  Do I need to drill fast or slow or sideways or something?  B^>

I guess you're also telling me that vibration from drilling isn't going to break anything either...

Rgds

Damon

PS. Not that I have a fuel-line clamp, not being a car owner, but I get the idea!

PPS. Here is the current schematic:

9884-0

« Last Edit: July 22, 2016, 01:14:29 PM by DamonHD »