MJLorton Solar Power and Electronic Measurement Equipment Forum
Solar Power => Solar Power => Topic started by: warlock on July 31, 2013, 08:29:30 AM
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Ok so here is my planned Solar Array..... Many thanks to ExSolar
10 x 250W PV
10 x i-Energy GT260 Micro-Invertor
1 x i-Manager
This to start and looking to grown it every 2 months by 500W for 10 months.
I am hoping to put my order in early next week, and will update with pictures.
If anyone can see an issue here please let me know.
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Right so the order has been placed and delivery expected next week, I have down sized to 1kW for the initial install and will then grow for there.
As soon as the kit arrives I'll take some photo's
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Ok my kit has arrived ;D
I have not unpacked it all yet but I will supply photo's as we go along.
I have strated the install and have got all the roof hooks in, I finished off in the dark so could not
get a picture of it complete but I'll provide what I have and update as we go along
Rook Hook Installation
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As I had said before I decided with the micro-inverter route, for 2 reason, 1. Far better shade tolerance and 2. simplicity of the install.
To install this like all or most micro invertors I simply daisy chain them to each other and thn from the last one in the line I connected 2.5mm surfix cable which runs directly into on DB board to a 2P 20A AC breaker and then from that break into the out of the mains switch.... I have no need to worry about DC cables and high voltages ect.
i-energy micro inverter and i manager
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1kW will do nicely to offset the daytime load in most probability. You probably will show zero power draw over the day, and if you have a mechanical meter it might run backwards as well as you feed power in to the grid. I would suggest a second meter bought from Litecorp or such to get a reliable figure of the power the panel array is generating. I would also suggest the next string has a separate run of 2.5 surfix to the DB , though you can use the same breaker to feed the power in. That way there is less loss in the cable and the inverters will be less likely to do an overvoltage trip on a sunny day.
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Thanks for the feedback Sean,
The I-Manager which I have also purchased, communicates with each individual micro-inverter, this allows me track the total power production and the individual panel production, it's quite cool coz then if there is a problem with a panel it will allow you to identify it from the web interface.
I do have a mechanical meter and from what I have researched I have found other people on the internet that have this same model meter running backwards so unless Eskom has done something clever "which I doubt" I should be good there.
With regard to the surfix, I might have it wrong but I am installing 2.5mm which is rated to 20A and 4000W, the i-energy micro-inverters allow up to 17 in a string for a maximum of 20A, so I am installing a 20A 2P breaker in the DB. the surfix run from the panels should not be more than 5m, so with this regard I should be good to my eventual install of 3kW,
If I am wrong please tell me before I install this surfix, by I was looking at the cables on the inverters and they too are only 2.5mm, I could always just install 4mm just to be safe ?
I have attached 2 more photo's I took this morning, I'll hopefully get the rail's, copper grounding and surfix in this afternoon.
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If it is only 5m or so you will be fine. The worry comes with a 30m length, which typically will have a 10% voltage drop along it, so the inverters will have to generate a 250-260V output to cover the cable loss. If you can put in a 4mm cable then do so, lower losses of the power you are generating is always good, and saves you later having to arrange a new run of cable to the panel connection. At the panel end I would also recommend a small York box with the connections inside so it is easy to add the extra panels in later stage as you expand. If you really want there you can use a small DB panel and just have 2 pole isolators inside to enable each string to be isolated from the system with ease.
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Cool shot for the info, I was thinking about it today and it's only like R30 more for 4mm cable so it's a no brain er to go for 4mm, I'll let you know how it goes.
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Ok so I managed to complete the install and happy to say I am feeding back into the grid.
1. First things first I rewired my DB, I replaced all the old style breakers with new breakers, I have a few more to change to
make them all uni-form, but I will do that over time.
2. I installed the rails onto the rook hook that I install
3. Attached the inverters to the rails
4. Mounted the solar panels.
Lastly flip the switch on the DB and presto we have power.
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Looks a lot better, and with the panels you now definitely will have a saving.
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Excellent stuff, you are playing with bits I hope to experiment with in the future. I think you have made a very wise choice in going the micro inverter route and being able to monitor each panels is such a bonus.
I want to put to 3 equal arrays side by side, one with grid tie, one MPPT CC and the other micro inverter to compare performance.
Thanks very much for your post.
May I ask how much each micro inverter cost and the I-Manager? I'm keen to see if this system costs much more than a normal grid tie? Still worth it in my opinion!
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I am fortunate enough to be able to run a small business so I get the equipment at dealer cost, but basically it cost about R2750 per invertor, each can do 240W-260W I have 250w panels attached, so for 2500w or 2500KVA it will be about R27500.
Since my last post I installed a further 4 panels so my array is now 2KW, and I have to say that I must at least be getting > 20% more production than a single string inverter. With the I-Manager "R3500" you can see historically and realtime, that often during the day as cloud's, tree's and morning's and evening as shadows effect the panels, 6/8 of the panels still producing 200W+ and the other 2 100W-120W and as the shadow shifts you can see it move on the array.
I am very impressed, the only thing is my roof is at about 18deg and we have just come out of winter where the inclination should have been like 56deg. So not good for winter but, mid to end spring they'll be perfect, for or summer months 2deg is optimum.
The installation was a real breeze and I did it all my self .With the i-enegery inverters you can connect a maximum of 17 on a bus, I say bus because each micro inverter is connected the next and so on and so forth, but the string acts as a busbar, so if one would fail the rest would still operate without hindrance. Then from the roof I used 2.5mm surfix under the roof tile and directly into a 2 pole 20A circuit breaker in my distribution board, from this breaker into the out of the mains 63A breaker. As simple as that and it complies with all safety regulations. This alone should convince anyone that micro-inverter is the way to go.
What I have also done is gotten hold of monitoring equipment from OpenenergyMonitor (http://openenergymonitor.org/emon/), I got the emonTX, emonGLCD and the Raspberry PI as the base station and boy am I impressed, together all of these monitor my Solar Gen and House Usage, Grid Import/Export, Power Factor, Voltage and basically anything else you want to add and posts everything to the locate DB on the Raspberry PI which can post to a web based system online "emoncms.org" and both are very configurable and have web interfaces Demo Dashboard (http://emoncms.org/trystan/solarpv), I have temperature controllers no their way and with these I'll be installing 2 on the hot water geyser and 2 on my solar water collector, I can them using the same emonTX monitor top and bottom temperatures of the geyser and solar collectors and with a bit of sketch code control the 12V solar pump to ensure at no point am I feeding cooler water into the geyser than what's already in the geyser, it will also give me an idea of the temperature through out the system. There are also guys doing load diversion with the same systems.
Anyways that's my 2 cents worth.
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Brilliant feedback and update Warlock. Great to hear it first hand and what the micro inverters are doing for you.
Please keep us in the loop with any further updates or challenges with your system. There are loads of folks starting to look at systems like this now and your posts add great value.
Cheers,
Martin.
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2kW Array Photo Update
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Very nice. As you are living in Kloof I would also suggest taking all the metal frames on the roof and connecting them via a 10mm copper cable to a lightning earth, 3 or more earth spikes wired together. Seen way too many dead modems, TV and DSTV sets from there, and have even seen light fittings blown to bits by near strikes. Ground all the metalwork via a short cable to reduce the build up of charge that can arc over and destroy the equipment. Do the solar water heater case as well while you are at it. Join all the mounting rails to the wire.
I see you cracked a few tiles, better replace them soon or the rain will find a way through and you will be playing at night with buckets and singing a song " Raindrops keep falling on my bed".
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The white conduit you see in the image contains the copper earthing wire which it attached to a ground spike and driven 3m into the ground.
Those cracked tiles "chipped corners" have always been there, the overlap is way bigger than the missing pieces but yes I should really replace them at some point.
Didn't do the solar water heater but that is a good point I should really do that too.
Today I produced 10.5KW and we had a bit of cloud cover, so I am well impressed. I'll give this array 6 months at which point I will probably add another 1KW
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Nice, good to see more Capetownian's going Solar :)
My install should be semi up and running this weekend, assuming it doesn't rain!
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Nice, good to see more Capetownian's going Solar :)
My install should be semi up and running this weekend, assuming it doesn't rain!
Excellent...do post some pictures and tell us about it when you are ready.
Cheers,
Martin.
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Cape Town, I'd never live there ;),
Ballito, KZN is where I am from..... Yes please do send some pictures,
Last week I added another 2.5sqm Flat Plate Solar Collector to my existing one and introduced another geyser, it's been working really well.
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So it's been just over 1 year since I installed all my Solar Equipment and Solar Geysers total Cost R75000, Electricity prices are rising again, and so far by my calculation I have been saving around R1500 or 75% of my monthly electricity bill (R18000pa). So basically I will have my system paid off in around 4 years.. What I have to clarify though is that majority of the Saving is the Solar Geysers, they probably account for 75% of the saving. Even so it feels good to know that in 3 years effectively I'll be having free electricity.
With that said, I have gone ahead and ordered another 1KW to add to my array and I'll be installing this weekend
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Hi Warlock,
Your system is almost exactly what I now intend to start building myself.
Just to clarify something for me. How does your system cut off in event of Eishkom going down ? I don't necessarily mean switch your
power off on your side, but rather how it stops feeding back into the (now offline) grid.
Shaughn
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Hey ShaughnK,
Anti-islanding protection safety feature that is built into all grid-tied and hybrid grid-tie inverters. Anti-islanding protection is a way for the inverter to sense when there is a problem with the power grid, such as a power outage, and shut itself off to stop feeding power back to the grid. This is because when problems arise with the power grid it is assumed that workers will be dispatched to deal with the issue, and they want the power lines to be completely safe, and not have electricity flowing from all the nearby PV grid-tie systems.
An important product of anti-islanding protection is that a purely grid-tied PV system will only operate when the power grid is active. If there is a power outage the inverter will shut off and although the solar panels may still be generating power it will not be sent to your house.
Effectively the inverters will switch off and stop production in the event of a power failure, what this does mean though is that when Eishkom goes down for load shedding or what ever reason, your inverters will also turn off and not produce power.
There are devices out there that do AC-Coupling "very expensive" which will automatically separate you from the grid and from a battery bank simulate a mini-grid which will fool the inverters to start up again. but with that comes a load of issue, like how do you get ride of excess energy you are producing and now using. From all my research from what I have found it's not worth it. Right now I have a separate essentials loads panel where all my lights are attached to and 1 plug point for my DSL and TV, plus my 220v solar water pump, these are connected to an inverter with a 400ah battery bank, which gives we around 24 hours of usage.
Hope that helps !
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Hi Warlock,
Thanks for the detailed reply. I do understand how a grid tie system works.
What I meant was I was trying to understand how your particular system is configured based on the components you have, as you were saying you were feeding power back into the grid.
I will send you a PM and perhaps we can chat when you have time.
Thanks
Shaughn
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Hi Warlock
What made you choose I-energy micro inverters. I am keen to build and install a PV system using micro inverters. If you want to build up a system slowly, it seems like the only way to do it. The problem is I'm not sure which system to go with. The big brand names seem to be I-energy, Renesola and Enphase. I'm sure there are others that I haven't seen yet. Does anyone have any advise or reasons why I should go with one or the other..
Regards
Paul
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Hey P_B
I chose i-energy coz that's what my supplier stocked. They have since changed to Rena solar, at the end of the day as long as you make sure they have good backing, 25 years warantee, and decent efficiency then I think you'll bbe ok, right now I have had to import my last 6 inverters from Germany as the current supply of i-energy are charging about R3500ea and I landed them for about R2200. Exsolar in Capetown sell renasolar for around R2700 and I'd get them there if I'd build again, unfortunately I have a i-management unit and need to stick to i-energy