# PV Solar - Battery or not?



## Maesus114 (9 Nov 2021)

I've got 2 quotes for Solar panels and the first quoted for 10 panels with an immersion diverter at a cost of €9,100 before grant (€7,300 after) generating 3.95kWp.
He said I wouldn't need a battery as they only hold 50cent worth of electricity anyway.

2nd quote was for 12 panels 4kWp at a cost of €11,800 before grant, €8,800 after. This quote included battery and immersion diverter.  This Company felt the battery was more important than the immersion switch.

2nd quote seems better but is who is correct?  Also how long does a battery last.  Are they like phone batteries that need replacing every 2 years?


----------



## Zenith63 (9 Nov 2021)

If your primary goal is to maximise your financial return on your solar installation then neither the battery or the immersion diverter tend to make financial sense.  The batteries are still quite expensive and do have a limited life.  The diverter is also fairly expensive and will be offsetting probably gas which is quite cheap compared to electricity.

However when I put mine in my priorities were more like: reducing how much fossil fuel I use (being more green), the pure gadgetry/techiness of the thing, a backup power supply if the mains is offline, and then saving money at the bottom of the list (mega nerd, what can I say).  If your priorities are more like mine then I'd definitely recommend the battery, it's great to see it covering all your nighttime usage and being able to run broadband/laptop during a power outage is handy.  I'd probably go for the diverter again as well, having hot water all summer 'free of charge' is quite neat.

FWIW on my battery the warranty states that it will have at least 70% capacity after 10 years.  So yes they do lose capacity, but nothing like a smartphone.

You should try to get as many panels on your roof as you can with the installation.  The panels aren't super expensive, it's the getting somebody up there to install rails etc. that adds up.  So while they're up there have them put up as many as possible.  You'll over produce on summer days, but in the depths of winter a 4kW system will only produce a tiny fraction of that so the more panels the better!  FWIW I put up 14 panels a couple of years ago, I could have fitted 18 and if I was doing it again today I would.


----------



## rustbucket (9 Nov 2021)

I would agree with above. Maximize the panels. 
If you decide to put more panels later or add to the system you might have to upgrade your inverter also.

I went with 8 panels and the inverter. No battery.

I am now looking at putting more panels up. I wish I had fronted up the extra at the time. 

I now have to upgrade the inverter and potentially add battery


----------



## Leo (9 Nov 2021)

Maesus114 said:


> He said I wouldn't need a battery as they only hold 50cent worth of electricity anyway.


If that's really what an installer said, find yourself a new installer.


----------



## Zenith63 (9 Nov 2021)

Leo said:


> If that's really what an installer said, find yourself a new installer.


Yeah that's not great!  The number of cents the battery can hold isn't the figure you're interested in, it's the throughput over a time period that matters.  That €0.50 could charge/discharge ten times a day and your saving would be €5 that day.

For reference I have a 5kWh battery in-place for 2 years now and the throughput has been about 4.5MWh.  So the battery has helped me use an extra €450 of my generated solar (4500/2 * €0.20/kWh).  The battery cost something like €3k after the grant, so it would take 13 years to break even at this rate.


----------



## ryaner (9 Nov 2021)

The batteries are likely to make a lot more sense when the newer meters with different amounts for different times of the day come in. Think charging during the day and discharging at peak time.


----------



## Baby boomer (9 Nov 2021)

You haven't hit break even at 13 years at that rate.  You're ignoring the time value of money and the fact that after 13 years your battery will have depreciated hugely in value, perhaps even to nothing and may need replacing. (Although in fairness, electricity prices are only going one way so that's likely to increase your annual savings a bit too.)  You need to look at what return you'd get from an alternative investment of 3k, maybe into a pension fund.  If you're a high rate taxpayer, a pension contribution of 5k costs you 3k after tax.  That should return a compound annual growth of 4% which is pretty close to your early years savings from your battery.  But that's compounded.  After 13 years, your pension investment has grown to well over 8k and is generating growth of 333 per annum.  Your 13 year old batteries certainly won't be doing that.

It's easy to get sucked into the virtue of the thing and subconsciously exaggerate the savings.  I love the idea of solar and "free" electricity from the sun.  Plus it appeals to the engineer in me.  But this is askaboutMONEY so the bottom line needs to be right too.  

Panels probably meet the bottom line test now, and have dropped hugely in price over the last decade.  Batteries need a far better price/performance ratio to be a good investment.


----------



## Maesus114 (9 Nov 2021)

Thanks for all the replies.  Sounds like getting a battery is probably better overall for night time use. Down the line we might have an electric car so than can take the excess generated when the battery starts to lose power.


----------



## rustbucket (9 Nov 2021)

Maesus114 said:


> Thanks for all the replies.  Sounds like getting a battery is probably better overall for night time use. Down the line we might have an electric car so than can take the excess generated when the battery starts to lose power.


If you are going down the route of an electric car get them to wire for the charger when doing this as it needs to be connected to the same system as panels, inverter as well as the fuse board. They will be doing all that anyway for panels and inverter. 

As far as I’m aware you won’t get grant for car charger unless you actually own the car or have proof of purchase.

Also be aware that when charging hybrid or electric cars that takes quite a lot of the energy that is generated by the panels which will affect the water heating.

If not enough power generated by panels they charge off the mains.

Therefore as suggested above go down the route of more panels now if that’s your plan for later


----------



## rgfuller (10 Nov 2021)

Those quotes aren't particularly good, there are alot of installers inflating costs at the moment so it's definitely worth shopping around.
A good rule of thumb I've seen on boards is 1k euro per 1kw installed, plus 500 euro per 1kw battery (after grant).
I've recently had installed a larger system, 21 panels (7.2kw) with 11 optimisers (due to shading), a 5kw battery, 6kw inverter and a hot water diverter, total 9650 after grant, generally though prices seem to be rising as the demand increases for components.

One other thing to note is that generally the system completely turns off if there is a power outage (generation and battery supply) this is to avoid electrocuting someone working on the mains, some batteries allow you to connect an 'extension' lead where you can plug in essential items during an outage, just don't expect it to supply the household mains.


----------



## AJAM (10 Nov 2021)

Zenith63 said:


> For reference I have a 5kWh battery in-place for 2 years now and the throughput has been about 4.5MWh.  So the battery has helped me use an extra €450 of my generated solar (4500/2 * €0.20/kWh).  The battery cost something like €3k after the grant, so it would take 13 years to break even at this rate.



Can you not also use your battery to save money during the winter? Charge up at night at €0.05/kWh and use it during the day at €0.20/kWh?

Saving €0.15/kWh * 5 KWh per day = .75 per day or about 70 euro over the 3 winter months. Reducing your payback period to less than 6 years.


----------



## Leo (10 Nov 2021)

AJAM said:


> Saving €0.15/kWh * 5 KWh per day = .75 per day or about 70 euro over the 3 winter months. Reducing your payback period to less than 6 years.


You're assuming 100% efficiency in the charge / discharge cycle and inverter there!


----------



## AJAM (10 Nov 2021)

Good Point, but I think a good Lithium Ion battery has a 90 to 95% Round Trip efficiency.  https://www.large.net/news/8bu43pr.html
So taking that into account it might be more like 63 euro instead of 70, but the payback is still less than 6 years.


----------



## Alkers86 (10 Nov 2021)

Maesus114 said:


> I've got 2 quotes for Solar panels and the first quoted for 10 panels with an immersion diverter at a cost of €9,100 before grant (€7,300 after) generating 3.95kWp.
> He said I wouldn't need a battery as they only hold 50cent worth of electricity anyway.
> 
> 2nd quote was for 12 panels 4kWp at a cost of €11,800 before grant, €8,800 after. This quote included battery and immersion diverter.  This Company felt the battery was more important than the immersion switch.
> ...


To go back to the OP's post:

Both of those quotes are poor value for money compared to what is available from the market with some shopping around. As mentioned there is an excellent long thread on boards.ie dealing with this and you will see how wildly the price varies from provider to provider.

Some batteries do have gaurantees given in a number of years, but many of them are actually for battery cycles - typically 5000. So you need to find out exactly which model of battery is being incldued and figure this into the calculation. 5,000 cycles of a 2.5kWh battery is only gauranteed for 12,500 units or about €2,500 worth of electricity at day rate. If you are charging the battery via night-rate or using the battery at night time, the value of this electricity drops significantly.

In my opinion it is madness to pay for a battery system now with the imminent announcement due of the feed in tarrif, where you will be paid for some of the excess electricity generated by panels. The detail of this could render batteries to be completely uneconomical. It is also not a big job to add a battery to a system at a latter date (new inverter is required).

If you're approaching this from a purely financial perspective, the quickest system to provide a return on investment will be the cheapest small system you can find with no battery and no diverter.


----------



## Dododo (11 Nov 2021)

What is the max PV capacity / output you can install on a private house? Is there a limit? Thanks.


----------



## Leo (11 Nov 2021)

Dododo said:


> What is the max PV capacity / output you can install on a private house? Is there a limit? Thanks.


Any more than 12sqm of panels will require planning permission, but there is some precedents where people were allowed more. If it's the feed-in tariffs that interest you, the capacity of the inbound connection will limit output. The standard domestic supply is 12kVA here.


----------



## Shirazman (11 Nov 2021)

Leo said:


> Any more than 12sqm of panels will require planning permission, but there is some precedents where people were allowed more. If it's the feed-in tariffs that interest you, the capacity of the inbound connection will limit output. The standard domestic supply is 12kVA here.



Some additional info here:    https://energyd.ie/solar-panels-and-planning-permission-in-ireland/ 

But the recent Bord Plenanla decision (details in the link) may have changed the ground rules.


----------



## Leo (11 Nov 2021)

Shirazman said:


> Some additional info here:    https://energyd.ie/solar-panels-and-planning-permission-in-ireland/
> 
> But the recent Bord Plenanla decision (details in the link) may have changed the ground rules.


Yeah, I wouldn't rely on a supplier's view of planning legislation, but I can only see the current limits being expanded.


----------



## Dododo (11 Nov 2021)

Thanks for that. Basically I was just wondering what was the max kw(h)s of PV I could install.


----------



## Shirazman (13 Nov 2021)

Leo said:


> If it's the feed-in tariffs that interest you, the capacity of the inbound connection will limit output. The standard domestic supply is 12kVA here.



That's an interesting constraint.   I have a 16kVA connection, which was installed a decade ago on the advice of my Heat Pump installer.   I don't really know whether it was needed or not, but decided to play safe! 
Does that mean that because I have a larger capacity connection, I would be able to upload more to the national grid, when the time comes? 
If so, would my potential increased upload capacity be in the region of 25% more than the standard connection, or is that too simplistic?


----------



## Leo (15 Nov 2021)

Shirazman said:


> If so, would my potential increased upload capacity be in the region of 25% more than the standard connection, or is that too simplistic?


No, it's as simple as that really, though a 16kVA line will support 33% more than a 12kVA one.

Whether that would make financial sense will depend on the tariffs available. I suspect that the buy-back element of small scale setups like this won't justify the investment on their own until the kits come down a lot in price, the savings on your own usage will be key.


----------



## Shirazman (15 Nov 2021)

Leo said:


> No, it's as simple as that really, though a 16kVA line will support 33% more than a 12kVA one.



 oh dear. Embarrassing maths!   Thanks for that.


----------



## Zenith63 (15 Nov 2021)

Leo said:


> If it's the feed-in tariffs that interest you, the capacity of the inbound connection will limit output. The standard domestic supply is 12kVA here.


Worth noting that the ESB have a 6kW output limit for microgeneration (or 11kW if you're on 3-phase).  You can put up more panels but the inverter would need to be 6kW or less.  Not sure what is involved in overcoming that 6kW limit or whether it will always be in-place, but it's also what the ESB used for their feed-in-tariff pilot so I'd say it could be sticking around.


----------



## Leo (15 Nov 2021)

Zenith63 said:


> Not sure what is involved in overcoming that 6kW limit or whether it will always be in-place, but it's also what the ESB used for their feed-in-tariff pilot so I'd say it could be sticking around.


Just a guess, but it may be to prevent a concentration of large deployments overwhelming the local infrastructure.


----------



## Maesus114 (8 Dec 2021)

I've since got a few more quotes and it does seem that it's hardly worth putting in a battery when there will be a feed in tariff next year.
I'm still finding it hard to get decent quotes, though, using the €1k per kw.  Closest is a company that quote a monthly cost over 10 years but ideally I'd prefer to pay upfront when the money is making nothing in the bank.


----------



## Zenith63 (8 Dec 2021)

FWIW I had good experience with NextGenPower if you want to try them. They were reasonably priced after a bit of haggling and there was no hard sell from them, just honest advice. I’d use them again if I moved.

I have no affiliation with them whatsoever.


----------



## silverfox239 (8 Dec 2021)

Interesting maths assessment of batteries....









						Home Batteries Now Make A Lot Of Financial Sense!
					

With the energy prices skyrocketing, the 'payback' period of a home battery (without Solar) makes a lot of financial sense at the moment.Website: www.ev-man....




					www.youtube.com


----------



## Alkers86 (8 Dec 2021)

silverfox239 said:


> Interesting maths assessment of batteries....
> 
> 
> 
> ...


That's specific to the UK. But also, until the details of the FIT are known his maths could be compeltely relevent or completely irrelevant. It's too much of an unknown at the moment.


----------



## silverfox239 (8 Dec 2021)

Nothing to do with FIT (Feed In Tariffs) or anything specific to UK. 

Just basic maths that you charge the battery at a low rate (usually night time rate) and use the battery to Power your house during the day instead of paying the top rate.

So if you have a SmartMeter in Ireland you can avail of the rates below for example.








						Switch to our best electricity and gas price plan | Electric Ireland
					

Find the cheapest gas and electricity price plan for you and switch to Electric Ireland today.




					www.electricireland.ie
				





*Electricity unit price*Day: 08.00 - 23.0024.44c per kWhNight: 23.00 - 08.0012.58c per kWhNight Boost: 02.00 - 04.006.79c per kWh*Gas unit price*5.769c per kWh


----------



## Leo (8 Dec 2021)

silverfox239 said:


> Interesting maths assessment of batteries....
> 
> 
> 
> ...


Quite a few issues there ...


Based on UK price plans with night rates of between ~7% and ~25% of the day rate. Very different story here where they are about 50%.
Assumes that battery storage systems are 100% efficient over charge and discharge cycles.
Ignores increased standing charge for night rate meter.
Ignores that day unit costs are more expensive 
Requires moving 16% of consumption to off-peak hours
He states energy prices won't ever drop back down and suggests they will keep rising ahead of inflation rates while also stating the night rate will forever stay at 5p??? But we already know oil and gas prices are dropping at the moment. 

Just rerunning his numbers on a 20p day rate and assuming a night rate of 10p as you'd have here, savings drop to £168 a year. Then take £60 off that for the increased standing charge, increase the day rate in line with what we see on typical day/night plans here and then you're under £150. Start to account for losses in the charge/ discharge and you're looking at a system that would need to last more than 40 years with no additional costs to break even.


----------



## silverfox239 (8 Dec 2021)

@Leo I think you have some out of date info. to base your calcs on


Smart meters are rolling out across Ireland at no direct charge to customer. https://www.esbnetworks.ie/existing-connections/meters-and-readings/smart-meter-upgrade
So no need for  night rate meter & therefore extra standing charge so get the reduced night rates
Ireland does have night rates roughly similar to the UK, see the table above from Electric Ireland

My key point is on a lot of the threads, batteries get bashed as being expensive & nice to have. But given SmartMeter rollout I think people should re-run the numbers.

FIT will help a little but just in Budget 2022 there is a €200 tax relief for money earned from FIT.  Anything over that and your taxed at marginal rates, so prob. around 50% tax mark for a lot of people considering this option. So when you play that into the numbers there is an argument to get a battery as better to keep most of the power for yourself and not get taxed on it.

Finally how many people this week (Storm Barra) would have liked to have a battery when they lost power.


----------



## Leo (9 Dec 2021)

silverfox239 said:


> Smart meters are rolling out across Ireland at no direct charge to customer.


I was commenting on the video as presented, it makes no reference to smart metering. 



silverfox239 said:


> So no need for night rate meter & therefore extra standing charge so get the reduced night rates


True, but the peak rates are also more expensive than on a standard tariff and the off-peak rate is significantly more expensive than night rate electricity. 



silverfox239 said:


> Ireland does have night rates roughly similar to the UK, see the table above from Electric Ireland


Who in Ireland provides night rate electricity at a discount of 75% or more? His numbers are based on 75 to 86% discount. 



silverfox239 said:


> My key point is on a lot of the threads, batteries get bashed as being expensive & nice to have. But given SmartMeter rollout I think people should re-run the numbers.
> 
> FIT will help a little but just in Budget 2022 there is a €200 tax relief for money earned from FIT.


Absolutely people need to run the numbers, but they need to run real life numbers that are relevant to the Irish market. Batteries absolutely are expensive, and for many people, they simply will not repay the investment within their lifespan, and that money would provide more value if invested in other energy saving measures. As battery technology improves, that will evolve, but there are very good reasons why these are not popping up on every new build or refurb. 

Also beware that feed in tariffs are on the way, there is every chance they will be phased out in the future. That's already happening in other markets due to local congestion issues in the low voltage grid brought about by the success of incentives for domestic PV.


----------



## Alkers86 (9 Dec 2021)

Leo said:


> Quite a few issues there ...
> 
> 
> Based on UK price plans with night rates of between ~7% and ~25% of the day rate. Very different story here where they are about 50%.
> ...


Exactly!

Also, the gaurantess on these batteries are typically 5,000 - 10,000 cycles. So a 5kWhr battery will only be gauranteed to last 25,000 - 50,000 units worth of electricity. That might sound like a lot but with an average price of 20c per unit that's only €5k to €10k worth of electricity when these batteries are often in the €5k ballpark price themselves.


----------



## Leo (10 Dec 2021)

Alkers86 said:


> Exactly!
> 
> Also, the gaurantess on these batteries are typically 5,000 - 10,000 cycles. So a 5kWhr battery will only be gauranteed to last 25,000 - 50,000 units worth of electricity. That might sound like a lot but with an average price of 20c per unit that's only €5k to €10k worth of electricity when these batteries are often in the €5k ballpark price themselves.


Yep, with the amount of investment going into battery development at the moment I think these might start to make sense in a few years when the cost/capacity ratio and lifespan improve, but it doesn't make much sense now.


----------

