Solar for Beginners [ask your questions here]

ELM327 · 13-12-2022 1:29pm

https://www.boards.ie/discussion/comment/119990814#Comment_119990814

So my north star is to have a system where I can do exactly the same as if I were grid tied, but be off grid. I need around 10kva minimum to go in and out of the batteries. I'll be buying calb cells and seplos bms so that's perfectly possible. Just the inverters arent clear in my head. Lets say I go to 30+kwp, how do I invert all that power!

slave1 · 13-12-2022 1:42pm

Here you go, this guy has put a lot into this house....seen a few of his vids...high cost but it will get you what you want

https://www.youtube.com/watch?v=n6PqMUfN-p8&ab_channel=TheDisruptionNetwork

ELM327 · 13-12-2022 1:55pm

That video was interesting but didnt go enough into the detail of the setup. We can't have tesla powerwalls here either.

https://www.boards.ie/discussion/comment/119990968#Comment_119990968

I have no choice but to stand still for the moment. Even going the CALB cells DIY route isnt cheap. I spent nearly 30k this year on the main solar PV and on a lot of gadgets and DIY bits. For that I have the main 8.2kWp system with 20kWh storage, along with a few add ons, UPSs, etc. I reckon it will be mid next year at the earliest before I can add on anything substantial.

We decided to go big on Solar as opposed to replacing the second EV for now too, so that's another outlay for next year that will need to compete with solar.

slave1 · 13-12-2022 2:02pm

His previous videos go into the house setup. You can have a Tesla PW here off grid. I'm of a similiar mindset on off-grid but I've maxed what I can do for the minute, 14kWp into two 6kW inverters into a Sofar Battery Inverter and 20kWh DIY batteries but I'm in an estate so horrible Nov- Feb shading

unkel · 13-12-2022 3:43pm

https://www.boards.ie/discussion/comment/119990972#Comment_119990972

All south facing or different aspects and how many strings? With @graememk and my suggestion of the 9kW Sunsynk hybrid plus a 6kW regular inverter, I don't think you'd get an awful lot of clipping even if all is south. The Sunsynk can charge / discharge the batteries at almost 10kW, so you will need at least 20kWh of battery for that. It can also handle parallel MPPT input strings, so you will have 6 strings max between the two inverters. Also a much cheaper setup than that Victron, the thousands of savings can go into more battery / panels

ELM327 · 13-12-2022 3:58pm

https://www.boards.ie/discussion/comment/119991666#Comment_119991666

I'd aim for predominantly south facing. But outside of maybe 4kWp more, the rest would be ground mounted and pretty flexible for direction (so south + southwest probably makes most sense).

So your suggestion is for one large hybrid inverter like the sunsynk, and then the rest into non hybrid inverter(s)?

So if I had

9kW sunsynk <->6kW solis <->6kW solis <->6kW solis

^

Connect-Multiples of calb cells grouped in 16S and paralleled

(Is this the chap by the way)

unkel · 13-12-2022 4:11pm

Yes that's the chap. Hard to get though, even though it's perfectly legal to use in Ireland, has the Irish grid settings built in and the right Irish cert too.

I'd go for mainly south but also E + W if you work from home. I'd start with just that chap and one 6kW conventional inverter. Ground mounts are very expensive in materials alone and if you don't DIY them, their ROI is questionable. Just maximise all the roof space first. With a large country house and an outbuilding or two, I'd have thought you could easily put up 20-30kwp. My small semi-D in an estate in Dublin will have 16kwp soon LOL

graememk · 13-12-2022 4:16pm

https://www.boards.ie/discussion/comment/119991787#Comment_119991787

Yep something along them lines.

Something to watch out for, I am not sure how big the seplos goes current wise, so maybe split into 2x 16s2p for 40 kwh

unkel · 13-12-2022 4:19pm

Seplos only goes to 150A, so no good for a Sunsynk that can do 190A, unless you buy two of them (waste of money though). Other BMS like the JK I got in the 11/11 sale can do both 200A and active balancing. I've yet to install it though, waiting for my new CALBs first.

ELM327 · 13-12-2022 4:32pm

https://www.boards.ie/discussion/comment/119991855#Comment_119991855

If you ignore aspect, then yes I could get around 35-40kWp up. Problem is that half of it would be either shaded and or north facing. So do I go ground mounted, or put more east/west, or buy more storage, etc etc. It's a balancing act. And I'm trying to ask the questions and understand everything before starting, this time!!

unkel · 13-12-2022 5:00pm

You will have to do some sums. As an example, a N facing panel installed for €250 incl materials on a roof has a better payback time as a S facing panel installed for €550 on a ground mount incl materials. The latter also has far more depreciation should you change your mind / change your setup / want to resell.

That said, ground mounts can be pretty cheap if you fully DIY, have lots of space and do it the "tree trunk" way that @Big Lar has done

13-12-2022 5:31pm

I'm thinking of getting 8 panels and a battery installed next year. However I have a question around the practicalities of the installation. We live in a very windy spot, how secure are the fittings of the panels to the roofing truss and also would the removal and re-setting of the roof tiles allow for any weakness to future wind ?

unkel · 13-12-2022 6:12pm

Don't worry about it, @[Deleted User]. The standard solar PV roof connections are rated for more wind than we've ever seen in Ireland.

redmagic68 · 13-12-2022 10:03pm

https://www.boards.ie/discussion/comment/119992268#Comment_119992268

I live on the side of a mountain and got an installation in November. Savage wind at times but we have slates not tiles. Once feb comes it’ll be proper windy. If mine don’t hold on I’ll let you know but having seen how and what is used I have no worries.

micks_address · 14-12-2022 5:44pm

Few people have been talking about optimisers re shading.. thought these where good videos on youtube about it

https://www.youtube.com/watch?v=9GvhDhCSJgo&t=488s

micks_address · 14-12-2022 5:46pm

Part 2

https://youtu.be/ESpsdMFEFZo

graememk · 14-12-2022 6:53pm

https://www.boards.ie/discussion/comment/119996535#Comment_119996535

They are very interesting.

Its a big ol "its complicated!"

micks_address · 14-12-2022 7:36pm

https://www.boards.ie/discussion/comment/119996824#Comment_119996824

I like his conclusions though that unless required for multi aspect roofs that an installation is probably better without them given the lifetime power usage potential failure rates etc.. I didn't realise that the panels have a reasonable level of shading management built in.

olympicweights · 14-12-2022 7:54pm

Perfect timing for my question relating to shading!

I had the northern lads install 7.9kwp of panels 2 weeks ago, 4.74kwp South facing and 3.16 East facing, and as of today I have generated 99kw.

They are to come back next week with the battery and zappi plus I had wanted to add an optimiser to my lower right panel on the South due to some shading.

There was good sunshine today so I took a few pictures of the shading and corresponding output data from the inverter. From what I can see the shading didn't affect the total output by a huge amount so I am wondering if I should bother with an optimiser?

Any feedback appreciated.

IMG_20221214_115424.jpg

IMG_20221214_115459.jpg

IMG_20221214_123608.jpg

IMG_20221214_123643.jpg

graememk · 14-12-2022 8:05pm

https://www.boards.ie/discussion/comment/119997053#Comment_119997053

I wouldnt, As an optimiser wouldnt help you in that panel as its fully shaded. Its likely the bypass diodes would have kicked in

2.978kw in the first photo, 3.647 in the second, Also the Sun would have been more direct onto the panels too in the second one so you would only been losing that one panel. And its december, you'll not be having that problem later on in the year

DC999 · 14-12-2022 8:08pm

https://www.boards.ie/discussion/comment/119997053#Comment_119997053

Don't consider optimisers at this time of the year. I'm only live 5 months and sun is completely different at this time of the year. Wait and take that same pic with the shading in March, July or Sept. If you've shading during the peak months, it may be worth it. So hang tight.

I've 5 on a flat roof and they are brill but roof gets shades all year at different times of the day. So they help in my case

olympicweights · 14-12-2022 8:15pm

Same roof, 7th April this year, 11:35am

img_20220407.jpg

olympicweights · 14-12-2022 8:17pm

It's just the lower corner panel that will potentially get shade before 12 earlier in the year

unkel · 14-12-2022 8:23pm

I didn't know there were several bypass diodes within a panel. I've been ranting and raving against optimizers and micro inverters for years, but that adds a very strong argument that most of the time they have little or no improvement to shading because of bypass diodes and MPPT

TL:DR

But my biggest Con always is that electronics fail, PV panels don't. If you have 20 micro inverters / optimizers on your high roof and they last on average 10 years, that means that you are up on your high roof twice a year to replace one of them. Which is nuts. The dude mentions something like this but strangely he doesn't have it in his above list of Cons

Don't use micro inverters or optimizers on your high roof!!!

This topic begs the question though: how much does a bypass diode in a PV panel cost and how much extra would a €200 PV panel cost to the end user if it had a bypass diode for every single solar cell?

bullit_dodger · 15-12-2022 2:57am

https://www.boards.ie/discussion/comment/119997174#Comment_119997174

Hmm.... while I can agree with the case for not using optimizers, I'm not so sure I would totally agree with the logic for not using micro-inverters. But to be fair, it's not a like-for-like comparison.

The way I look at the logic for optimizers is that you also have to have a string inverter....but with micro-inverters you forgo the cost of the string inverter. So on a cost level, a set of micro-inverters is probably cheaper than "optimizers and a string inverter". If a micro-inverter fails, you just lose that panel (or 2 panels if it's a dual Microinverter).

If a optimizer fails - what happens? Do you jsut lose that panel or does the string suffer? (Dunno)

unkel · 15-12-2022 12:01pm

@bullit_dodger - You're missing my point. A string inverter is located in an accessible location, you don't have to go onto your high roof. It fails every 10 years, so that is a job you only have to do once every 10 years. 20 microinverters also fail every 10 years, but that means a failure on average every 6 months. They are located on your high roof, an inconvenient location, so you will be up on your ladder every 6 months to replace it, or worse - get a man to do it for you. Like I said, installing these (on your high roof) is insanity.

micks_address · 15-12-2022 12:27pm

hi folks,

does anyone have a zappi 2.1 and eddi 2.1? Noticed my Eddi had gone offline this morning.. a reboot seems to have fixed it.. just curious if anyone else seeing that kind of behaviour.. It all seemed fine in the app - but on the cloud dashboard was showing up as inactve. Couldnt see grid import/export in the myenergy app either..

Cheers,

Mick

con747 · 15-12-2022 12:31pm

https://www.boards.ie/discussion/comment/119999277#Comment_119999277

There was a Solis inverter firmware upgrade earlier in the night if you have a Solis maybe that could have caused it?

micks_address · 15-12-2022 12:39pm

https://www.boards.ie/discussion/comment/119999288#Comment_119999288

No I'm in givenergy.. could have been any update.. anyway just curious the see if anyone else experiences the same.. I already had the zappi replaced once so not that assured of its resiliency

bullit_dodger · 15-12-2022 1:15pm

No no - I got your point about the accessibility of the roof, but the probability math doesn't work that way :-)

If optimizers have a MTBF of failure as 10 years, and you have 10 optimizers, then on average it's not a failure every year. Each individual device has a MTBF of 10 years. Course the device could also work for 20 years (or 30 years) without failure too. Don't forget that.. as that's important. MTBF isn't that it will last 10 years and then die on the spot, but rather that the device has a expected lifetime of 10 years. Basically there will be "some distribution" of failures which average out at that 10 year mark. It's also worth remembering that MTBF isn't a probability. It's related, but it is different.

Usually (most) electronic devices have a "bathtub curve" of distribution failures where it will be likely to die at the start of it's life and then drop to a flat level and rise at the end of the expected lifetime - with the length of the flat section dependent on the stress put on the device.

Computing the probability of a single device failing in any specific year is actually hard. It's called a "hazard function" and it's dependent on a range of things, primarily the failure distribution curve. I could bore you some more, but if anyone is interested there's plenty of stuff on the web if you want to look it up.

But back to the point of optimizers v micro-inverters. I do agree with you to generally avoid optimizers, but there's some good sound engineering reasons to use micro-inverters. If a micro-inverter fails, yes you have to get a guy out onto the roof. Sure - that's annoying, but you've lost one panel. But if a string inverter fails and your using optimizers, your completely down (all panels) and most likely even though it's accessible, chances are you won't have the skills to replace it yourself (unless you happened to be a spark). So you have to get a guy out in that case too and string inverters also have a MTBF too of course. So you remove that probability with micro-inverters.

I'm not arguing that you should never use optimizers (or string inverters) only saying that ultimately while less devices is generally a good thing, optimizers & micro-inverters are perhaps not as likely to fail as you would think. The main thing for me is money. People spending €1K on optimizers and then not realizing that you might generate 1Kwhr/day more for 3-4 months a year. waste of money for a lot of people.

Solar for Beginners [ask your questions here]

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