Domestic Solar PV Quotes 2022 - No PM requests - See Mod note post #1

deadl0ck

Just got my first quote and wondering what people think (new to all this - sorry):

Solis hybrid 5kW inverter

Solis wifi datalogger

Jinko 430 watt N type solar panel on slate portrait

Weco 5.3 kWh battery

AC isolator

DC isolator

Battery Isolator

4 pole automatic switch

45A kWh meter

Associated electrical work and testing

System Annual yield - 5125 kWhs

SEAI grant details

€2400 will be paid directly to customer by the SEAI

Sub Total : €11,000.00

Total before grant : €11,000.00

Does that seem like a good starting point and are the solar panels and battery brands any good?

HotSwap

https://www.boards.ie/discussion/comment/120893713#Comment_120893713

How many panels?

jkforde

https://www.boards.ie/discussion/comment/120893713#Comment_120893713

does it include SEAI grant submission? include post-install BER assessment?

deadl0ck

https://www.boards.ie/discussion/comment/120894455#Comment_120894455

OK - Didn't know about those costs !

Actually - do I need a post BER assessment? what's it for ?

And is the grant submission a very complicated process or why would I need someone to do it?

deadl0ck

https://www.boards.ie/discussion/comment/120893782#Comment_120893782

14 from what I can see in the quote

jkforde

with decent CEG rates (export payments), why not cover that roof with another 10? 😁

the BER (required by the SEAI for the grant) and grant application can be included by some installers as a sweetner but keep on top of them in terms of actually doing it right and on time.

aaaaand NB!... make sure your NC6 is submitted to ESBN and get written (email) confirmation that they have it on file and logged with the correct commissioning date.

sligopaul

https://www.boards.ie/discussion/comment/120895045#Comment_120895045

If that is net 8600 after the grant for a 6kw system and 5kw battery it doesn't look too bad to me, as mentioned above you could ask how much additional panels are ( Maybe not 10 though ☺️ ), at this time of year you would be maxed via the invertor but during the winter months you would definitely receive some benefit and you appear to have the roof space

HotSwap

https://www.boards.ie/discussion/comment/120893713#Comment_120893713

It’s a good quote. Just don’t pay the full 11k to the installer. Withhold the 2400 until you are paid by SEAI. You have no guarantee that they will complete the install to SEAI guidelines and you could be left in a situation where you cannot claim the grant.

This would be a deal breaker for me and if they are reputable they will accept having this written in the contract.

deadl0ck

Thanks.

Are the panels and battery brand ok?

ColemanY2K

https://www.boards.ie/discussion/comment/120897044#Comment_120897044

Yes they are reputable brands.

JPMCM

hi all great board I'd appreciate your insights on the implications of having an undersized inverter. Due to my current wiring layout, I'm restricted to a 3.5 kW inverter. However, I'm planning to install 6 kW worth of solar panels on the roof, which has an east-west orientation, with 8 panels on each side. I also have a legacy 1.2 kW set of panels, powered by a Sunny Boy 1.2 kW inverter, that I aim to keep. Given this setup, I wonder if the size of the inverter could significantly hinder my system's performance. I'm also planning to add a 5 kW battery to the system. Our annual power consumption fluctuates between 3500-4500 kWh and we are planning to make this investment within the next year

ColemanY2K

Your inverter can only handle a certain amount of PV power coming from the panels. In my case I have a 5kW hybrid Solis inverter which can handle a maximum array size of 8kW. It will never exceed the 5kW output but the array will help get it thrre. Have a look at what the recommended max PV power (DC side) your inverter can handle which will inform you the max size of array you can have.

10-10-20

https://www.boards.ie/discussion/comment/120897479#Comment_120897479

A very good article on over-sizing here.

https://energyd.ie/dc-over-sizing-pv-solar-in-ireland/

I must say that I should have factored it in better myself, I tried to obtain a 1:1 ratio of DC to AC where it's really not needed in Ireland and you have the additional outlay of the higher priced inverter then to factor in.

Do you have the option of adding panels onto the Sunny Boy at all, because in that article it does mention that some Sunny Boys have a 2:1 DC to AC ratio, so perhaps that's a runner if the panels can be sourced? That would give you a welcome boost in Winter for sure.

deezell

Once the inverter string DC voltage no load maximum is well clear of maximum combined string panel voltage (your 8 panels in two strings, around 320v max each typically), then you'll be OK. The inverter will only draw enough current to deliver 3.5kw to the grid for use or FIT. The oversizing of panels will extend the period of max delivery, as even at half power of say 200w/panel they will deliver 3.2kwh.

With a hybrid inverter, the battery management should be able to store excess to the battery, so your potential additional 2.5kwh or greater of excess is available to charge the battery. You need to make sure that the chosen inverter spec has the capacity to do this. There is an overall limit applied to the inverter input, meaning your additional panel excess is unused.

Take the Sungro 3.6kwh. for example. Max in at the panels is 11.7kwh. Max out to grid is 3.68kwh. Max to battery charge is 6.6kwh. So the inverter can divest 10.28 kwh to grid and battery, assuming your battery can charge at the rate of 6.6kwh.

Your 6kwh panels are well within spec, but on full potential output with a fully charged battery, will only deliver 3.5 to the grid, the rest will be surplus and unused. Have a gander at the Sungrow data sheet.

EN_DS_SH3.0RS_SH3.6RS_SH4.0RS_SH5.0RS_SH6.0RS_Datasheet_V123_20210906-1.pdf

An interesting feature of this inverter is its backup or off grid mode, allowing panels and battery to supply power to a selected circuit of your home wiring in the event of mains failure. While on grid this is limited to a combination of inverter and grid feedin to 6kwh, so could be most of your home use, excepting maybe 4 plate hobs, electric showers and heatpumps. In off grid mode it's the inverter limit of 3.68, but can cope with 8kva bursts for 10 seconds, say from motors in fridges, pumps, oil boilers etc. Used carefully this could provide critical protection from power outages for perhaps several hours depending on daylight and battery charge.

DC999

https://www.boards.ie/discussion/comment/120897479#Comment_120897479

An undersized inverter (relative to panel output) is fine on an E/W split. But installer needs to check the inverter spec for how oversized it can take on panels. Unlike S, the E+W aren’t both getting full light at the same time. I’ve an E/W split.

What’s the 3.5kW wiring limitation for that inverter in your house? Many kettles uses up to 3kW, as a comparison. Electric shower can be 10kW.

I’d agree with 10-10 to check what more you can add to the existing inverter at the same time. Could be spare capacity in that.

Houses will only ever use more electricity (EV, electric heating like heat pumps..). So your current 3500-4500kWh usage will climb in time. I’d suggest get the largest setup now that your budget, roof and wiring can handle. A 3.5kW is small is you’re trying to charge a car and run your house.

10-10-20

I'll just throw it out there that I looked at the Voc (voltage open-circuit) on a few common panels as this is the main value which tells you how many panels you can fit on a string. It's interesting to see some of the variation:

• Trina Vertex 430w : Voc: 51.4v
• Longi HiMo5 405w: Voc: 36.95
• Rec Alpha Pure 420w: Voc: 59.4v.

So on an inverter with a input voltage limit of 600v, at standard temperatures (!! read : https://www.greentechrenewables.com/article/solar-inverter-string-design-calculations !!) you would be looking at a string max of:

• Trina Vertex 430w : String max: 11 (4730w)
• Longi HiMo5 405w: String max: 16 (6480w)
• Rec Alpha Pure 420w: String max: 10 (4200w)

So yeah, there's that.

deezell

https://www.boards.ie/discussion/comment/120898503#Comment_120898503

There's bound to be some loading on the string inputs under no inverter load or power off conditions. Pure open circuit voltage might be misleading. I'd be interested to see what a modest high resistance termination would do to individual panels voltage, and also a set in series. After all, theres 220 volts on the tip of a phase testing screwdriver until you stick your thumb on it and it lights up.

10-10-20

https://www.boards.ie/discussion/comment/120898756#Comment_120898756

Yes, and I accept that, but there is method to the calculation of the string-max as covered off in that article linked.

deezell

Its probably moot anyway for domestic installations. You're unlikely to put all your eggs in one basket on a single inverter string, and with two strings and the max no of panels you'll be way past the output limit for on grid. I can't imagine having two strings of 16 panels with a potential 13kwh farting into a 5kwh inverter, unless you're near the North Pole. The more panels, the more potential for a single underperforing, shaded, or birdshit covered panel to choke all the others in the series, hence the use of strings. The oversizing idea is a good one, an extra 4 panels should really only add maybe 1200 to an install to give you a decent amount of oversizing, and the chance of useful return in winter, dull days and morning/evenings. At a guess I'd say that over 10 years even, you should get back the €120 per annum in a cost benefit analysis. Its less than a kwh a day on average at current prices

deezell

I'd fully accept though the method of calcuating input max. Better to be save than sorry. A string thats perilously close to the maximum connector voltage under no load is far more likely to fail if any sudden induced voltage adds to the DC, and causes a flash over or rupture in the input gubbins of the inverter.

graememk

https://www.boards.ie/discussion/comment/120898756#Comment_120898756

Ive seen my panels reach VoC when the grid is down/throttling due to export limit.

Also need to account for temperature too, Trina and REC seem to run at a higher voltage, useful for low number of panels in a string, the Longi Himo ones run really low, but at a higher current which allows for a lot of oversizing.

Id be firmly in the over sizing camp as id say the majority of days in ireland, you arent at the maximum output of the inverter anyway, and just suck up the clipping and dont worry about it.

Shading isn't as big of an issue either with the bypass diodes, If a panel has a hard shadow from a pole/roof, it is simply bypassed and doesnt bring the rest of the string down. Its got to a point where optimisers are really only useful for diffuse shading, eg from leaves on a tree.

Tiger20

Hi, just looking for advice/opinions please. Quote received for a 7.4kw system,

18 x 410w panels, 9 East, 9 West (house gable more or less S)

1 x 5kw Solis inverter

1 x 5.3kw Weco battery

Eddie water diverted, and all associated fittings

Quote is €11500 pre grant

Wondering about 5kw inverter with a 7.4 kw system, assume it’s because 9 panels East, 9 West so assume that’s it, but would a 6kw inverter be needed?

Thanks

con747

https://www.boards.ie/discussion/comment/120901500#Comment_120901500

ESBN restricted inverter size a couple of months ago to 5kW https://www.esbnetworks.ie/new-connections/generator-connections-group/micro-generators- but with an east/west split you should be alright with it. Put your quote into the calculator http://davidhunt.ie/solar/

randombar

https://www.boards.ie/discussion/comment/120901571#Comment_120901571

Do you know what the story with the grant is?

I too am looking at an east west split.

I am putting in a new inverter (insurance) replacing my old 6kw one and would be interested in a larger one for the higher grid to battery charge. Via the inverter I could limit the export to 6kw.

Would the grant not pay out based on inverter size or anything like that?

graememk

https://www.boards.ie/discussion/comment/120902350#Comment_120902350

If you got a grant this last time your not eligible for it again unfortunately

randombar

https://www.boards.ie/discussion/comment/120902407#Comment_120902407

No grant the first time.

idc

https://www.boards.ie/discussion/comment/120902350#Comment_120902350

According to ESBN rules for NC6 your not even allowed use export limitation! If you want that and higher than 5 kW (in reality they allow up to 25A) your supposed to apply for NC7

10-10-20

Just so we're clear, the allowed MEC (Maximum Export Capacity) rating for micro-generators at single-phase is equivalent to 25A and that's based off the published "continuous steady-state rating 'X' amps" of the inverter. Where multiple inverters are fitted and are grid-attached, then the rated outputs are combined in this respect. So 5kW isn't strictly correct as a 5.8kW inverter would probably be rated at the max allowed capacity. Example below from Sungrow:

So if the inverter is rated for more than 25A but has a configurable generation limitation of 25A, then it's still not approved as the overall generation capability of the inverter is higher than 25A.

https://www.esbnetworks.ie/docs/default-source/publications/conditions-governing-the-connection-and-operation-of-micro-generation-policy.pdf?sfvrsn=fdcb2515_17

DC999

https://www.boards.ie/discussion/comment/120902407#Comment_120902407

Insurance should cover that gap as you won't be grant eligible. If it were me, I'd replace with the same size and tyoe inverter as that was approved by ESBN. So a like for like replacement. OP shouldn't need an NC6 resubmitted if it's a straight swap - IMHO.

idc

https://www.boards.ie/discussion/comment/120902431#Comment_120902431

Fair enough, aware of that but in general most inverters seem to be 5 or 6 kW. (22.8 or 27.3A) there doesn't tend to be a version in between those two sizes.

From the image above the SG3.6RS was probably added to match the max size allowed in UK without applying to DNO.

That may be changing as did find a Renac 5kW inverter can output max 25A max/ 5500VA. So I guess there are options out there for people to still max out there inverter to the 25A limit.