Is it worth our while?

unkel

Not sure if you are right there @Alkers - it's a simple calculation though when planning an install, get quotes for different size systems. Say a kwp extra costs €800 installed. This makes 800kWh per year south facing in a good area of Ireland. That makes well over €100 tax free return per year in FIT if you don't use any of it yourself, worst case scenario. That's an extremely high return on a low risk investment

In Germany many people chose to have PV installed solely to feed in to the grid (they get a higher FIT when doing that), purely as an investment

Alkers

https://www.boards.ie/discussion/comment/119620203#Comment_119620203

Not every extra kWp will earn €100 in fit though, particularly if you are already coming close to the €200 tax free allowance on fit

unkel

@Alkers - You mention 2.5-3kwp as the sweet spot, you can add a few more kwp before you hit the tax free threshold. And the sums are quite simple really. To dismiss it even just from an investment point of view without doing these sums is unwise.

bullit_dodger

Yeah, I'm sort of with unkel there - although technically your right Alkers. If you have a smaller system, it's true you will have a higher self-consumption rate. Logically if I install 1x 400watt panel and my base load is higher than that, I'lll be at 100% self-consumption. Leave aside the FIT side of things for a minute, getting a high self-consumption rate is good as it does mean in theory I'd have the shortest payback period.

The problem where that logic breaks down is in the fact that 1x 400 watt panel is worth feck all to me. So naturally we need more than that. 1x 400 watt panel in the middle of summer might do 400 watts, but in the middle of Sept it ain't going to produce that. So we typically size for Sept/Oct and Feb/Mar. Where it gets interesting is that a string inverter will cost the same if I have 1 panel or 12 panels, so the embedded "inverter cost per panel" is cheaper with 12 than 1. This is (partly) why also why over on the quotes thread the bigger systems tend to be better "value" compared to the formula - that and the fact that it costs the same to get 2 guys on your roof for 1 panel verses 12 panels. (I won't go into micro-inverters here)

So what's the sweet spot then? Ironically I don't think there is one, or at least I think every house is different due to roof orientation, consumption profile (when in the day), annual consumption (how much per year), EV usage (eg. needing 1.5Kw minimum generation for some cars) , battery installation. You need to size the installation to the needs.

That said, I think 3Kwp is a good well balanced system. I think most people installing one will do very well with it.

Aside: Not seeing why hitting the tax free threshold is bad. Yeah, nobody wants to pay tax, but if I'm earning money from panels (after paying tax) why is that a bad thing? I certainly wouldn't size a system to stop me from reaching that threashold. It wouldn't even enter my thinking

[Deleted User]

https://www.boards.ie/discussion/comment/119611213#Comment_119611213

https://www.boards.ie/discussion/comment/119611700#Comment_119611700

To put this in perspective: I have the kind of skills that are liable to get me somewhere between slightly and terribly injured, so anything that involves picking up tools is a no-no for me. I'm not joking - I have some useful skills alright, but they do not involve electricity, gas, water or sharp implements.

I've a good head for research, but I need to allocate time to it sparingly.

The reason I'm asking here is precisely because it is an echo chamber. The upside of that is that there are people posting here with real-life experience, and that has to be useful to us. On the other hand, it does mean running into the "enthusiasts" point that @Girl Geraldine references. If this kind of work is something you're enthusiastic about, then all the researching, analysing, finessing and tinkering about is a delight, whereas for me it's an absolute pain in the arse. In clichéd terms, I'm looking for point-and-click, or plug and play. And being honest, regardless of my environmental concerns, if the choice is between spending wads of money now and getting it back over 20 years, or spending more or less the same wads of money spread out over 20 years, then maybe the hassle of installation isn't worth it.

But I'd still tempted. I think we have a setting that's as good as you'll get. East coast, and an almost due south facing big roof with nothing blocking the light. On the other hand, there's not a chance we'd be doing any of this ourselves, so it'd be a case of quotes for paid installation all the way - which would make initial costs higher and the payback period longer. I think there's still a bit of thinking to be done.

Thanks for all the comments (so far, as I'm still reading the thread).

Bobeagleburger

Don't overspend with the thoughts of earning it back with FIT.

Get plenty of quotes. You should be able to get a 6kW system, 7.2kW battery and Eddi for 11-12k post grant. Not brilliant, but compared to some of the quotes I've seen it's ok.

Careful of posters disguised as installers, especially on that Facebook page. Less likely here but it happens.

Good luck.

Remember these ball part post grant calculations. If it's near this you're good. Otherwise run away.

1.2k per 1kW panels

1250 per 2.4kW battery

500 Eddi

unkel

It most likely will pay back quicker if you go for the largest possible system in terms of PV panels, but with NO diversion of any kind. No hot water immersion diverter, no diversion to an electric car and certainly no battery. Get quotes for a plain 6kwp system and let the generous FIT (feed in tariff) system do its work...

More Music

https://www.boards.ie/discussion/comment/119616655#Comment_119616655

12,000kWh per year - holy sh1t. So what would your PV panels reduce your ESB mains electric consumption to p/a? Or what would you be happy with?

I used 4048kWh for the whole of 2021. I'm at 2744kWh so far in 2022. That's with no panels or any supplemental generation.

This is what pisses me off. You can conserve and insulate etc. to reduce your costs (or even install panels) and they just jack up the price anyway.

I cannot reduce anymore, or we will be living in the dark.

I'm at a level I'm happy with. Maybe I should install PV and export most of it back to the grid!!

loopymum

I'm almost afraid to post here how much we use per year in kw

I might start a survey.

We are electric only

No gas or oil of any description

2 electric cars albeit one is very lightly used

unkel

Don't feel bad, @loopymum. Here's why your usage probably isn't all that high, these are rough figures but you get the picture:

An average Irish home uses 3MWh in electricity per year if heated with gas / oil and if there are no EVs plus about 1500m3 of gas (equivalent is 16MWh in electricity) plus 18000km in diesel which is about 1000l (equivalent is 10MWh in electricity). Total 39MWh

If that household does electric only has the same basic 3MWh, and modern electric heating with a heat pump uses about half above, so say 8MWh an EV that does 18k km per year at 18kWh / 100km uses about 4MWh per year after charging losses . Total 15MWh, so less than half of above in reality and much cleaner and greener as more and more of this is coming from renewables, while oil / gas / petrol / diesel are almost zero percent renewable and do have tonnes of emissions!

graememk

https://www.boards.ie/discussion/comment/119644345#Comment_119644345

Thats something that seems to be overlooked quite a lot when heatpumps are involved.. there's no gas bill.

[Deleted User]

https://www.boards.ie/discussion/comment/119640062#Comment_119640062

https://www.boards.ie/discussion/comment/119640394#Comment_119640394

Differing views in those posts.

We don't have a hot water tank or an EV, so what @unkel says might be more relevant to us. How big (in roof area) would a 6 kW system be?

A battery would help us time-shift, and presumably save money on bills. But it adds cost to the installation, whereas FIT doesn't (does it?). But without a battery, and with relatively little consumption during the weekdays, is it not the case that most of the time we'd be generating electricity and sending it straight to the grid?

slave1

https://www.boards.ie/discussion/comment/119644248#Comment_119644248

When I was on a longish commute pre COVID we were 20 MWh a year, is what it is

unkel

@Ulysses1874 - 6kwp is roughly 16 panels of the most typical size sold these days which is about 1.76m*1.04m and about 375W

Unless you do a lot of cycling the battery, build your own and buy the cells cheaper than they are available for in the market right now, with the current generous FIT a battery simply won't pay for itself. Now of course, the FIT could go down, the day rates could go further up, the battery parts might hold their value really well, etc. plenty of variables in there

That's coming from me BTW, I have tonnes of renewables, both a large solar thermal system and a huge solar PV system and a 20kWh battery and a Zappi to divert excess electricity to the car when the battery is full. I am on the cheapest night rate available in Ireland as per renewal a few weeks ago (7.9kWh) and I do a lot of peak shifting so I barely use any day rate electricity

ELM327

https://www.boards.ie/discussion/comment/119644068#Comment_119644068

My panels are only in a couple of weeks so I'm as yet unsure what they will reduce it to.

I'll be happy when I'm off grid!

In terms of money spent vs money saved, the best way however would be a small array to cover the base load of the house in summer. Paid back in 12-18 months

DC999

@unkel, yeah, I convinced myself we were amazing with a house using only 2.8MWh a year. But then we had no EV. And cook on gas and heat on gas. So electricity was only one of our 3 energy bills (as patrol is basically an energy bill). Now with the EV we’ve only 2 energy bills (petrol is gone), and I can use electric rads (a little from solar) to supplement the gas heating outside the full on winter (so can reduce gas a little).

Our EV uses the same amount of juice as our house now pretty much. Which is still a surprise. I did the maths when buying it, so was aware. But to think your mode of transport (which for us is low mileage) uses as much as a whole house….Shows how wasteful cars are. Not suggesting I flog mine, but are heavy to run.

Will move off gas cooking in the future for sure. And always planned too. Less gas we use, the better. 

DC999

https://www.boards.ie/discussion/comment/119644068#Comment_119644068

Get PV anyway and it will reduce your bills big time. As others said here, I waited and should have gotten it sooner. Only live 2 months but will never live in a gaff without it again. We're all gonna use more electricity in the future (EVs, more from gas cooking and heating, more tech in houses...).

Energy costs are only going one way and not just for a year or 2, imho. Solar gives you control back from those. Look at solar as a service if shelling out in one go isn't a runner. It's the same result. Enjoy the hunt!

waterwelly

https://www.boards.ie/discussion/comment/119645248#Comment_119645248

People need to be wary about energy costs only going one way, obviously there was a major shock to the system (Ukraine) which resulted in gas shortages, high oil prices and a run on coal as everybody paniced.

I believe this will ease and energy prices will fall slowly over the next few years, maybe not to where they were but it will fall.

Even if the Eur improves against the dollar, which it always does at some point, oil and gas will be cheaper.

Now I am still going all in on PV at some point but I am cautious about paying top dollar right now.

maxpet

https://www.boards.ie/discussion/comment/119618691#Comment_119618691

Do you charge a battery with this setup ?????

Ubbquittious

https://www.boards.ie/discussion/comment/119646111#Comment_119646111

No not yet. I am working on it though, going to make a charge controller and have a change-over so I can send the power from the panels to either the grid tie inverter or charge controller

tom1ie

Hi all, so what sort of price would you be looking at for supply and installation of a typical 6kwp array which as per previous post I understand to be approx 16 panels?

This would be no battery as any excess I’d be looking to go to FIT.

Dublin area.

Also is there a limit to the size of array you can have or the max amount of panels? Do you need planning permission once you go over a certain amount?

[Deleted User]

https://www.boards.ie/discussion/comment/119644917#Comment_119644917

I'd guess that 16 panels is about half of my south-facing roof.

https://www.boards.ie/discussion/comment/119645229#Comment_119645229

See, if I was able to use a bit of solar electricity to power electric rads and cut the gas heating that would be a real bonus. But of course I'd be generating less leccy at just the time of year I'd need the heating. Ah well.

yankinlk

https://www.boards.ie/discussion/comment/119652321#Comment_119652321

The formula is in the FAQ sticky... so 6Kw x 1.2Keuro = 7200euro after grant. Check this against the quotes thread and get 3 quotes minimum

Good luck

tom1ie

https://www.boards.ie/discussion/comment/119653382#Comment_119653382

Many thanks and I should’ve read that sticky first before posting- very informative.

unkel

https://www.boards.ie/discussion/comment/119653333#Comment_119653333

Well, you would be surprised. The colder it is, the better PV works. Today started a lot colder than it has been recently but as soon as the sun was out, my car was being charged with the max 7.4kW the charge point can provide. Purely from the sun. While I also have some small electric radiators running in the house

unkel

Taken just now. Anytime the sun is out, even in autumn or spring around the midday hours and car is charging at max rate from the sun:

ELM327

Today was the first day I saw over 7kW being generated too

unkel

Nice one, welcome to the club! My mate here in the same cul-de-sac has an even slightly bigger setup than me. If the sun is out in full, between the two of us we power the baseload of the entire estate (about 80 houses)

slave1

Due (I assume to high voltage) I get 7.6kW max into to car

graememk

https://www.boards.ie/discussion/comment/119662020#Comment_119662020

7600/32 is only 237V So not that high a voltage, although decent when pulling 32 amps!