Solar for Dummies.

Fantana2 · 14-01-2022 10:08am

https://www.boards.ie/discussion/comment/118471061#Comment_118471061

What would be the max amount of panels on one aspect for a 6kw inverter? I’ve read you have to be careful with the voltage.

Manion · 14-01-2022 10:18am

A 400watt panel is 2 meters squared (varies by vendor) so 15 panels or 30 square meters would be needed for 6kw. The max would probably depend on your usable space no? I think you're asking about multiple arrays.

MAULBROOK · 14-01-2022 11:43am

https://www.boards.ie/discussion/comment/118472283#Comment_118472283

Don't over think it. Its very easy to fall down a rabbit hole on Solar and believe me I did.

Talk to a few installers and take it from there

The max as far as I know is 8kw.

THE ALM · 14-01-2022 12:27pm

https://www.boards.ie/discussion/comment/118472283#Comment_118472283

We have 24x340w JA Solar panels on a Solis 6kw inverter, 12/string.

Technically we could add another two on a string as the inverter can take a max of 600v but I think that would really be pushing it and I like to leave a little headroom.

I think if we are going to add extra panels it would be on a different aspect with 2nd inverter etc but not really a need for us at the minute.

bullit_dodger · 14-01-2022 1:39pm

I believe that there's a little headroom built into them too, they can take 640-650v typically, but not "all" the time. Like a spike up there for a few minutes won't blow them, so if your sub 450v, you should be able to add 2x safely enough. (They are about 38-40v each)

But sure you have 24x panels - you've loads :-)

unkel · 14-01-2022 1:42pm

https://www.boards.ie/discussion/comment/118471061#Comment_118471061

Hey! That is my system exactly 😁

MAULBROOK · 14-01-2022 1:46pm

https://www.boards.ie/discussion/comment/118473775#Comment_118473775

You are my inspiration.

Mr Q · 14-01-2022 2:57pm

https://www.boards.ie/discussion/comment/118472283#Comment_118472283

It depends on the inverter. I have a 6kW SMA inverter and the datasheet has 9kW as the max. But it could most likely take more once within the max voltage and max current limits.

bullit_dodger · 14-01-2022 5:20pm

I'd say 13-14 panels would be about the max on 1 string with a small buffer. Depends on what the nominal voltage output of the panels as well as the inverter. The web is your friend there.

Usually (not always) the limit is a max voltage "per string" issue. As Mr Q say above that also depends on the inverter, but virtually all of them are in about 600V. So with it being (approx) 40V per panel, your looking at roughly 15 panels per string. If you had 370w panels, that would equate to about 11kw in panels, assuming you split the 30 panels equally between strings.

Note: While you could probably safely do that, just because you can do it, wouldn't equate to that you should do it :-) You'd be wasting a lot of production with that config, as your inverter will only pull down 6Kw, even though you paid for 11Kw in panels, so a bit of a waste.

unkel · 14-01-2022 5:27pm

I've 12 panels on one string and someone on here whose knowledge and experience I would trust as beyond repute recommended that was the maximum for my combo. To not go any higher. I had space for 14 panels, so I reluctantly restricted the string to the 12. Now this would of course depend on the panel and on the inverter. And in my case I did look at the spec sheets and 13 panels would have sent the max voltage over the voltage the inverter can take in on a string as the max.

JimmyVik · 14-01-2022 5:39pm

https://www.boards.ie/discussion/comment/118473157#Comment_118473157

That looks cool. How many square meters is that?

Are they facing south?

bullit_dodger · 14-01-2022 5:44pm

I mentioned 13-14 above, but having a look at my own panels.....

looks like I was wrong and it could be as much as 45V per panel. What I don't know is if the inverters limit of 600V is a "open circuit" voltage limit or MPP voltage limit. I suspect open circuit... but I'm not sure. So unkels limit of 12 is probaly the "more correct" answer.....though I reckon I could sneak in 13 if I needed, but 12 is probably the wise move.

THE ALM · 14-01-2022 6:01pm

https://www.boards.ie/discussion/comment/118475555#Comment_118475555

Thanks JimmyVik. About 40 sqm and all facing south, slightly ssw (200°) to be exact.

Deagol · 15-01-2022 1:01pm

https://www.boards.ie/discussion/comment/118475577#Comment_118475577

It's OC voltage. Personally I think 12 would be as much as I would chance.

bullit_dodger · 15-01-2022 1:20pm

https://www.boards.ie/discussion/comment/118479221#Comment_118479221

Thanks mate - I thought that was the case alright, but good to have it confirmed.

slave1 · 16-01-2022 12:06am

https://www.boards.ie/discussion/comment/118475477#Comment_118475477

I know it would depend on a lot of things like ascetics/aspect etc but you could just throw up two panels with micro inverter…

unkel · 16-01-2022 12:51am

Oh I know. I have the microinverter right here. In fact I have two of them 😁

millb · 16-01-2022 7:29pm

I've just installed 3.8 kW (4+1s & 5w) with microinvertors and a Solis invertor with 2.4kWh battery.

Below is the system graph for today - can somebody tell me if the system report / monitoring data is correctly assigned?

AckwelFoley · 20-01-2022 5:22pm

Met with a rep today from a company in tip. They have good reviews and I liked him, wasn't pushy plenty of good info and practical knowledge as he is an electric himself and has been fitting.

We have quite a high consumption.. over 5000kw per year. He has suggest proposed a 6kw system with a 6kw solis inverter and and a 5.3kw Battery with a diverted for the immersion

Waiting on a price but my question is, is it a reasonable expectation to get 50% of my annual need from this? I appreciate it a "how long is a piece of string" question as there is factors involved, but if we keep our usage to daytime should we achieve this. I'm trying to do the cost benefit, o don't mind spending the money if it will pay back rather than rot in the bank and still pay high esb bills

Annual yield of 4750 was mentioned, but again knowing other factors and lower yield in winter and potential excess in summer, would I be expecting 50% of my annual need? Ie cut the cost of my annual purchase of esb kws

bullit_dodger · 20-01-2022 5:35pm

We have quite a high consumption.. over 5000kw per year.

Don't know what you'd call my 12,000/year then! :-) Actually 4000-4500 is about the average mate for a household in Ireland, so your not that far above the average. As for the expected yield of a 6Kwp in panels. there are some pretty good tools out there on the web for forecasting that. I use....

https://re.jrc.ec.europa.eu/pvg_tools/en/#PVP%20that's%20the%20calculator%20for%20Europe,

but you'll need to know your orientation (which you didn't specify above in your mail) if it's east/south/west etc and the angle of the roof.

A 6Kwp in panels does sound "about right" for you. My (personal) rough guide these days is

minimum 4.0Kwp - sure there are reasons you'd go lower (like lack of roof space), but to make serious inroads into your bills you need 4.0 Kwp.
your average household in Ireland would be in the 5.0-6.0Kwp range
6.0-8.0Kwp - If you have or planning an EV in the near future or you have excessive consumption (over 6,000 units per year)

More than 8.0Kwp is possible of course, but then your getting into more specialized installations, and you can't really have general guidelines.

50-60% is not totally unrealistic. A lot depends on your panel orientation, size of battery, how (what time of the day) you use your stuff etc

AndyBoBandy · 20-01-2022 5:46pm

10,058kWh used last year, and I'd consider that average...

~5,000kWh would be on the low side...

MAULBROOK · 20-01-2022 5:51pm

https://www.boards.ie/discussion/comment/118506871#Comment_118506871

Screenshot_20220112-215710_Solis Home.jpg

Hope this helps, 6.2kw system with a 5kw inverter

bullit_dodger · 20-01-2022 6:01pm

https://www.boards.ie/discussion/comment/118507026#Comment_118507026

I'm talking more about what the average household in Ireland is, not so much about you or me Andy.

What are Average Gas & Electricity Bills in Ireland? (selectra.ie)

Specifically..

The Commission for Regulation of Utilities (the CRU) is tasked with monitoring and collating information from Irish electricity and gas providers. According to the CRU, the average annual usage of electricity for an Irish household is 4,200 kWh.

AckwelFoley · 20-01-2022 6:06pm

Our pitch is about 30 degree, south facing

The rep referred to an optimiser.

If one panel is suffers from shading, it reduces the efficiency of all panels because they're linked.

Apparently an optimiser stops all panels differing from reduced efficiency ifnits put on each panel. He wasn't hard selling it, but was mentioned

bullit_dodger · 20-01-2022 6:17pm

Plugging 6Kwp with an azimuth of 0 (south facing) yields this as the expected generation.

These are estimates, but they are generally (reasonably) accurate +/- 10%

What he mentions about optimizers is correct. If one (or more) panels have shading on them it drags down the arrary to the yield of that one panel, so for every panel that has shading you should install an optimizer on.

AckwelFoley · 20-01-2022 6:54pm

https://www.boards.ie/discussion/comment/118507174#Comment_118507174

Really appreciate that.

Now for the stupid question

What is considered shading? It's an obstruction for any period of time during the day? And is the optimiser needed for only that panel or for all of them?

bullit_dodger · 20-01-2022 7:11pm

Firm believer in "no stupid questions"

So, basically it's any significant shadow/shading which is falling on the panels in bright sunshine. Shading doesn't come into play on a cloudy day as the panels, while not generating as much as full sunshine, they are creating energy by "diffuse lighting".

A good example of shading would be panels next to say a chinney, and the chimney's outline would be covering some or all a panel. If the entire array was shaded by a tree (for example) then optimizers won't solve that. it's only really if one or more of the array is in shade, but there are others which are in full sunshine.

Bear in mind that as the sun changes through the year, there maybe times where an optimizers are helpful and other times of the year they are not needed, but if you can avoid them....do avoid them. They are €100 per panel and they can go defective. Pain in the ass if 7-8 years in you need to get someone out onto your roof - but they definetely do solve some problems in some scenarios and are worth installing.

Bellie1 · 20-01-2022 7:17pm

Got a quote from a company. Only now checked the seai site and they're not listed as registered. I assume the seai is up-to-date? This crowd are partners of electric Ireland so had assumed were regulated.

graememk · 20-01-2022 7:56pm

An example of shading, it doesn't need to be much, your hand could nearly do it.

https://youtu.be/AbxHoQF4ADk

MAULBROOK · 20-01-2022 10:05pm

https://www.boards.ie/discussion/comment/118507539#Comment_118507539

What are the details of the quote. Main utility companies can be pricey

Solar for Dummies.

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