Domestic solar PV quotes 2018

DrPhilG · 25-04-2019 01:40PM

KCross wrote: »

How does the garage gets its electricity supply? There might be a duct where they can push a cable through?

There is presumably a duct, not sure where it is or how easy the access would be though.

There is a small fuse board setup in the garage and the current charger is wired back to there.

unkel · 25-04-2019 01:55PM

DrPhilG wrote: »

Apologies, typo. It was just under 9.

Don't want to be a spoil sport, but that figure is not realistic. Did the installer give you that figure?

With a 4kwp system in Donegal, I would expect about 3000kWh per year total production or so. If you use all of this production to power the back load of your house (extrememly optimistic best case scenario), this is worth 3000 * 18c/kWh = €540 per year, giving you a payback of €7500 (net cost to you) / €540 = 14 years

In practice, you will use some of the electricity to charge your car (which is only worth 8c/kWh), some to sent to your immersion diverter (which is worth only 4-5c/kWh) and no doubt you will still lose some electricity to the grid on long sunny days in summer when your battery is full and your water cylinder fully heated and your car is not charging

So realistically it's more around the 20 year mark. Still fine, most of your system will still be working fine by then, so the real savings can then start. And of course you will have done your bit for the environment / your fellow human beings. And of course we could get a FIT in future, you might add cheaper batteries, electricity prices might go up, all of which could make your pay back time better.

DrPhilG · 25-04-2019 02:07PM

unkel wrote: »

And of course we could get a FIT in future, you might add cheaper batteries, electricity prices might go up, all of which could make your pay back time better.

True. I do think a FIT will arrive in time and prices sure ain't coming down.

PS what about the value of electricity stored to the battery overnight and used during the day? I'm damned if I can find the calculations I did previously but that was definitely a consideration for another €100 a year or so.

Also the installer didn't give me any calculations other than estimating production of between 3000-3400 output per year.

niallers1 · 25-04-2019 02:13PM

Plus there is also the smug satisfaction with generating your own power and the nerdiness factor of it. That's worth a couple of k.:D

and if you are heating your hot water that could be worth you €80 per year by not having to heat with gas.

unkel · 25-04-2019 02:19PM

DrPhilG wrote: »

PS what about the value of electricity stored to the battery overnight and used during the day? I'm damned if I can find the calculations I did previously but that was definitely a consideration for another €100 a year or so.

Yes that will save a bit. But only in winter really. If you program your hybrid inverter to charge the battery (all year round) at night rate for use in the morning, there is the risk you will pay 8c/kWh and your solar in the morning has nowhere to go but to your hot water at 4-5c/kWh, so you would actually lose out

If you get a full cycle of your battery say 183 days per year, you will save 4.4kWh (usable) * (18c-8c) * 183 = €80 per year. This is very optimistic though and you will lose money on sunny days in winter when you are not using up this storage before PV wants to fill it up again. Take a year off your pay back maybe realistically

unkel · 25-04-2019 02:20PM

niallers1 wrote: »

Plus there is also the smug satisfaction with generating your own power and the nerdiness factor of it. That's worth a couple of k.:D

Absolutely. Hallelujah!

DrPhilG · 25-04-2019 02:21PM

niallers1 wrote: »

and if you are heating your hot water that could be worth you €80 per year by not having to heat with gas.

I have oil heating and that also heats the water. But much of the year we only have it on for 3 hours a day so we don't always have enough.

Evd-Burner · 25-04-2019 03:12PM

unkel wrote: »

Yes that will save a bit. But only in winter really. If you program your hybrid inverter to charge the battery (all year round) at night rate for use in the morning, there is the risk you will pay 8c/kWh and your solar in the morning has nowhere to go but to your hot water at 4-5c/kWh, so you would actually lose out

If you get a full cycle of your battery say 183 days per year, you will save 4.4kWh (usable) * (18c-8c) * 183 = €80 per year. This is very optimistic though and you will lose money on sunny days in winter when you are not using up this storage before PV wants to fill it up again. Take a year off your pay back maybe realistically

The Solis inverter can be easily set to charge at night or not. Few clicks of a few buttons. If you did 4 setting changes I year I worked out another 60 savings a year.

AidenL · 25-04-2019 05:05PM

I haven’t paid my deposit yet, but having read the last few posts, I’m wondering is it dead silly of us all getting into something with a 20 year payback time.

And we will all need new batteries in ten years time, thus pushing out payback further.

I’m actually having second thoughts.

KCross · 25-04-2019 05:11PM

AidenL wrote: »

I haven’t paid my deposit yet, but having read the last few posts, I’m wondering is it dead silly of us all getting into something with a 20 year payback time.

And we will all need new batteries in ten years time, thus pushing out payback further.

I’m actually having second thoughts.

Thats the conclusion I came to. The payback is too long on the battery systems. By the time you've broken even it will be degraded by some unknown (but likely significant amount) and out of warranty.

It really depends on how important the payback time is to you. Maybe you have money burning a hole in your pocket or making you nothing in the bank and you want to reduce your monthly outgoings and you want the do your bit for the environment. All good, fair enough.

If you care about payback you need to be realistic on how you calculate it. If you are basing your payback on sales literature or on using all the generated energy or on what the salesman is telling you you are fooling yourself.

wexfordman2 · 25-04-2019 06:27PM

DrPhilG wrote: »

I have oil heating and that also heats the water. But much of the year we only have it on for 3 hours a day so we don't always have enough.

Yep, my inverter is the same. During the over Christmas period, having got my first bill, it was hard to figure out what NY actual savings were as I am on level pay, but I did notice that fir the first time ever, I had used more night rate units than day rate, so over half my electricity was at cheap night rate, and the remaining portion was either free solar or else day rate.

Today, I have imported nothing from the grid so far. 20kwh generated, 2kwh exported and 18kwh consumed. That being said, last night my battery was still over 30% charged and lasted until about 5am this morning (house was empty yesterday from 6:30 till midnight as we were visiting relatives).

Edit, .ine is a 6kwp system with eddi and battery, so my export figures are low generally with this, and my self consumption seems to be in excess of 80%. Qe do make an effort to run appliances as during the day, have energy efficient appliances and a smart washing machine which allows us to remotely activate it. The dryer is a heat pump dryer which is very efficient, and gets loads of use from.free solar.

unkel · 25-04-2019 09:03PM

AidenL wrote: »

And we will all need new batteries in ten years time, thus pushing out payback further.

I reckon they will last longer than a lot of people today think. They will deteriorate, but with the relatively low C values of charging / discharging (typically around 0.5C max) and the battery management not letting them go to far up or down it could very well be possible they still are usable after 15-20 years with perhaps 60-70% capacity left (provided the lithium batteries are indoors - so at an ideal temp of around 20C most of the time)

The panels will be good for many decades and replacement inverters / batteries will become a lot cheaper than they are now

And it's not all about the money. Our children and our children's children will despise our generation for the way we are leaving this world to them if we don't make some sharp changes now

DrPhilG · 25-04-2019 09:45PM

At the end of the day the panels are by far the biggest cost (certainly in my case) and they have by far the longest warranty.

€7600 of the €11900 total in my quote is the panels but they have a 30 year warranty.

niallers1 · 25-04-2019 09:50PM

I reckon I'm on track to save about 500 euro per year compared to what I have paid in bills in the past . My PV system (cost 6k net ) so about 12 years at current electricity prices.

I'd expect electricity prices to go up . It usually goes up roughly 5% per annum.
Over the past 7 months I've used 90% of what has been generated thanks to the battery and good usage of appliances .. delay starts, not putting on everything at the same time. Etcetera.

If I get my hands on a cheap diverter on UK eBay( seen solar iboost before for less than 200 euro) I think I could keep it at 90% for the whole year. That would be great.
Heating tank with excess would save me heating with gas for 6 months of the year.

unkel · 25-04-2019 10:56PM

DrPhilG wrote: »

At the end of the day the panels are by far the biggest cost (certainly in my case)

Shouldn't be. 4kwp costs a touch over €1100 + VAT at trade prices

The biggies are the hybrid inverter, the batteries and the install costs...

DrPhilG · 25-04-2019 11:37PM

unkel wrote: »

Shouldn't be. 4kwp costs a touch over €1100 + VAT at trade prices

The biggies are the hybrid inverter, the batteries and the install costs...

Lol, right again. I just rechecked his quote, the €7600 is for the panels and inverter installed. Battery is listed separately at €3600 Inc installation.

I should probably just shut up now as I don't know my arse from my elbow, lol

KCross · 26-04-2019 09:54AM

unkel wrote: »

I reckon they will last longer than a lot of people today think. They will deteriorate, but with the relatively low C values of charging / discharging (typically around 0.5C max) and the battery management not letting them go to far up or down it could very well be possible they still are usable after 15-20 years with perhaps 60-70% capacity left (provided the lithium batteries are indoors - so at an ideal temp of around 20C most of the time)

Time and cycles are much bigger issues for Li-ion than C-rate. High C rate would cause further degradation of course but its not the primary issue.

The home storage batteries are being cycled everyday so are at the edge of what Li-ion is capable of over a 10-15yr period. EV batteries are generally not cycled fully everyday, so last longer.

However, I'd generally agree with your 60-70% figure. Thats a reasonable guesstimate. The fact it has degraded to that means it takes longer to break even and when it does it takes longer to get anything meaningful out of it after the break even.... a 2.2kWh battery down to 1.3kWh after 10 years wont give you much from then on.

And the reality is, we just dont know how long these small home storage batteries will last because they havent existed long enough yet. Using EV batteries as your baseline is not apples to apples.

If the battery paid for itself within, say, 5 years I'd have gone for it and be happy to chance the degradation as I would have had 5 years of "making money". There is just no margin in these batteries to take a 10-15 year risk and if you have to replace them after 15 years the environmental aspects are questionable then as well as these batteries are not exactly eco friendly to manufacture.

A Solar PV only system is much more eco friendly and is guaranteed to last decades. That, along with a FiT, is what I'm vying for.

randombar · 26-04-2019 10:49AM

The best day of the year so far for me. 2019-04-18

3.3kw panels split sw and se with 2.4kwh battery

https://www.dropbox.com/s/8qx5ep4njyghzt4/Screenshot%202019-04-26%2010.48.20.png?dl=0

KCross · 26-04-2019 10:56AM

GaryCocs wrote: »

The best day of the year so far for me. 2019-04-18

3.3kw panels split sw and se with 2.4kwh battery

https://www.dropbox.com/s/8qx5ep4njyghzt4/Screenshot%202019-04-26%2010.48.20.png?dl=0

What do graphs 2-4 represent?

randombar · 26-04-2019 11:00AM

Sorry cut wrong

2) Charge Power
3) Consumption Power
4) Buy energy power

KCross · 26-04-2019 11:03AM

GaryCocs wrote: »

Sorry cut wrong

2) Consumption Power
3) Charge Power
4) Buy energy power

ok, i get 2
3 and 4 dont make sense to me though. They peak at 7kW. I presume your battery cant take 7kW so is it the amount being taken from the grid or is that graph 4?

Can you clarify how to interpret 3 and 4

EDIT: I think graph 3 is energy going into your battery. So, whats graph 4 showing?

randombar · 26-04-2019 11:06AM

KCross wrote: »

ok, i get 2
3 and 4 dont make sense to me though. They peak at 7kW. I presume your battery cant take 7kW so is it the amount being taken from the grid or is that graph 4?

Can you clarify how to interpret 3 and 4

Updated there again, sorry, in the middle of something else here.

2) Consumption - car charging on night rate.
3) Battery charging up
4) Again car charging on night rate.

unkel · 26-04-2019 12:15PM

KCross wrote: »

If the battery paid for itself within, say, 5 years I'd have gone for it and be happy to chance the degradation as I would have had 5 years of "making money".

Agreed, I have tried to make the figures work for me. I got a very good quote for a battery installed under the grant scheme and it wasn't good enough financially. I just couldn't justify it. I also explored doing a DIY install, with second hand inverter and as cheaply a lifepo4 battery I could source or build (friendly electrician hooking the system up for free) and those figures didn't work for me either

I'm a persistent fecker though. I'm still going ahead with battery storage, but with very cheap lead acid batteries. Costs so little that there is virtually no payback time (I should be able to sell my hardware for as much as I paid for it), so very little risk. I can replace the lead acid batteries with lifepo4 in the next few years / if their price has dropped significantly. Or decide not to go for lifepo4 batteries at all if we get a FIT that has higher rewards

KCross · 26-04-2019 12:38PM

unkel wrote: »

I'm still going ahead with battery storage, but with very cheap lead acid batteries. Costs so little that there is virtually no payback time (I should be able to sell my hardware for as much as I paid for it), so very little risk. I can replace the lead acid batteries with lifepo4 in the next few years / if their price has dropped significantly. Or decide not to go for lifepo4 batteries at all if we get a FIT that has higher rewards

What kWh would that Lead acid system be?
What would its physical footprint and weight be? Just thinking of where it could be put and would it have to be ground floor?
What are the costs? A few hundred?
Do you have to buy a "special" inverter that has a lead acid BMS?

unkel · 26-04-2019 12:45PM

Lead acid doesn't need a BMS like lithium. I have bought a second hand AC side battery inverter (similar setup as Tesla Powerwall). It has two CT clamps on mains incomer and PV, on which basis it decides to charge / discharge the battery. It checks battery temps alright.

Not sure yet about battery costs but not willing to spend much. A basic 4 * 100Ah 12V leisure battery setup would give you 5kWh (only half of that usable), but I am hoping for something a lot bigger than that. Weight could be huge and footprint easily a few sq meters. Will install outdoors. Wouldn't want lead acid inside my house.

garo · 26-04-2019 02:31PM

wexfordman2 wrote: »

So, 10,800 before grant?

As was suggested to me when I got a.similar quote, bargain them up to a slightly.larger system up to 6kwp solar.

Also, query the usable capacity of the battery, for example your 4.8kwh battery may only provide 90% of that as useable power, so 4.3kwh usable.

Post up the make and type.of inverter and battery too

Grant is 3800 so 11.5k before grant and VAT. It is a SolaX Hybrid X1-4.6 inverter and their triple power battery. https://www.solaxpower.com/en/triple-power-battery/
Battery is actually 4.5KWh w/ 90% depth of discharge so 4.05KWh usable.

randombar · 26-04-2019 02:55PM

Can anyone tell me the depth of discharge for the Plyontech batteries?

Also I still can't get a definitive answer on what the definition of a cycle is? Every day my battery is charging and discharging several times. e.g. Cloud cover, Oven goes on etc. all swaps from charge to discharge.

n97 mini · 26-04-2019 03:01PM

unkel wrote: »

Lead acid doesn't need a BMS like lithium. I have bought a second hand AC side battery inverter (similar setup as Tesla Powerwall). It has two CT clamps on mains incomer and PV, on which basis it decides to charge / discharge the battery. It checks battery temps alright.

Not sure yet about battery costs but not willing to spend much. A basic 4 * 100Ah 12V leisure battery setup would give you 5kWh (only half of that usable), but I am hoping for something a lot bigger than that. Weight could be huge and footprint easily a few sq meters. Will install outdoors. Wouldn't want lead acid inside my house.

What make/model inverter did you buy? Interested in something similar eventually, once DC coupling has finished leading me down a rabbit hole

KCross · 26-04-2019 03:42PM

GaryCocs wrote: »

Can anyone tell me the depth of discharge for the Plyontech batteries?

Also I still can't get a definitive answer on what the definition of a cycle is? Every day my battery is charging and discharging several times. e.g. Cloud cover, Oven goes on etc. all swaps from charge to discharge.

I believe Pylontech use an 80% DoD.

A cycle is when that 80% is achieved... so, it can be one cycle from 100-20-100 or it can be 8 cycles of 100-90-100 and everything in between.

Silent Running · 26-04-2019 05:51PM

KCross wrote: »

A Solar PV only system is much more eco friendly and is guaranteed to last decades. That, along with a FiT, is what I'm vying for.

This, in spades!

When the people start to arrive grinning on your doorstep looking for a vote, tell them that you're not happy that the ESB refuse to allow a workable FIT. Ask them what they plan to do about it.

Domestic solar PV quotes 2018

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