How much are Solar Panels worth

[FANTANA]

Have you calculated how much the battery alone was saving you? I wonder what the benefits would be of just getting a battery.

It’s still in its first month so early days, at the moment I’m charging every night from 15% (my min discharge level) to 100% so 13.6kwh (85% of a 16kwh battery) at 0.09 per kwh. That’s €1.22 per day to charge, if I discharge to cover my day rate say 12.24kwh (10% losses AC to DC) at 33 cent that has saved me €2.82 per day. Do this for 365 days that’s €1029 a year. This is probably best case as there will be days where I don’t use the battery fully to cover my day rate and may force dump at my FIT rate 19 cent. So call it €700 to be conservative. The battery cost me €1400 so should pay for itself in two years.

Would I get a battery only probably not. A hybrid inverter costs about €1500 the panels are actually very cheap really. To install an inverter you’d need an electrician. Then set up your battery yourself. If you ever get panels you are back getting an installer out again and you will probably need the same installer as I doubt they like touching other people’s work.

My 2 cents is get as many panels as you can afford/fit on your roof and get a hybrid inverter. Then install a battery when you can afford it.

 

[peemac]

sing your own figures a return of €789 per annum on an investment of €9,000 is 8.77%

2% on €9,000 is €180 before tax, that’s €120 after tax. Well if that doesn’t entice you fair enough, you must be rich.

Its maximum savings based on being able to use solar for every unit I use. That's unlikely.

I possibly would earn some money from selling to the grid, but I can't see the unit price they are offering lasting especially as wholesale rates are circa 10c-14c. The fake savings put about by solar companies where they always use the maximum non discounted unit rate and a maximum output of the panels is off putting

Unfortunately not rich, but plan to move to triple glaze windows as a priority. That will save on high heating bills. Thankfully I know someone in that industry, so should get an attractive price and the new grant. Solar will probably be after that

 

[ClubMan]

and the new grant

I presume you mean this?

Windows and doors grants

Upgrading your windows and doors for more energy efficient ones will help keep the heat in your home and improve comfort levels.

www.seai.ie

 

[_OkGo_]

The correct (and only) way is to estimate your total cost for electricity based on your usage and what plan that is (Plan A) and then do the same including your solar (Plan B). The difference is between these plans is what you actually save.

That’s €1.22 per day to charge, if I discharge to cover my day rate say 12.24kwh (10% losses AC to DC) at 33 cent that has saved me €2.82 per day. Do this for 365 days that’s €1029 a year. This is probably best case as there will be days where I don’t use the battery fully to cover my day rate and may force dump at my FIT rate 19 cent. So call it €700 to be conservative. The battery cost me €1400 so should pay for itself in two years.

That is completely wrong as I've already outlined. You need to compare your usage against the most appropriate plan with/without solar/battery.

You are only on the plan with a 35c day rate to make use of the battery and EV charging. Without knowing the details, you are probably saving something closer to €300 or less with your battery.

Still good but not even remotely close to a 2 year payback

 

[faketales]

I have been looking at this myself, trying to understand where the value is between panels and battery. I have installation planned for a 10kwh battery but am paying about €3k for that.

Some thought:

Things are very different if you use electricity for cooking and heating vs if you don't, if you do seasonal difference is huge for electricity usage and the opposite of solar gen. obviously.

I looked at adding a second battery but the return is not as good as the first as it would only be needed for offsetting for a few months.

The modelling completely changes if the FIT rate drops, currently it's almost two different systems most for half the year. Export solar and offset using battery to run the house. In fact if you used no electricity you could buy low and sell it back high, not sure on the business case on that.

There are other limitations sure as charge rate so if you go too big with a battery you cant charge in a two hour cheap window.

Kilowatt.ie has a pretty good modelling tool where you can upload your ESB data and show savings across all plans not just the one you are on. The best plan before solar/battery is unlikely to be the best after. In my option you have to compare the best plan for each setup to understand the value, some are more focused on solar panels than battery offset.

Pinergy seem to come up tops for me, thats due to them having the best FIT. Although they even recommend you switch plan (and pay the exit fee) between summer and winter. Get a high selling price in summer and cheaper buying price in winter.

Some scenarios I looked at via kilowatt

The savings are against my current plan, about 4 months ago, pre solar obv. but with a night time charge window for EV.

Scenario 1
16 panels, 10kwh battery (8 usable)
Save: €2,832 Pinergy

Scenario 2
16 panels, 20kwh battery (16 usable)
Save: €2,883 Pinergy

Scenario 3
16 panels, no battery
Save: €1,782 Pinergy

Scenario 4
no panels, 10kwh battery (8 usable)
Save: €503 Flogas

Scenario 5
no panels, 20kwh battery (16 usable)
Save: €550 Flogas

Panels saving: €2,300 / year
10kwh battery saving: €1,050 / year
But you cant add both together as different companies and plans.

Ratio both down in proportion with the €2,883 saving means multiplying each by .86.

My costs are about:
Panels €8.5k
10kwh battery: €3k

Payback:
Panels: 4.3 years
Battery: 3.3 years

I am not fully convinced the tool is using the battery fill / sell back to it most. But running full cycles like that does impact the battery life I believe.

Comparing it to an investment I think the Internal Rate of Return would be about 18% (I leaned on ChatGPT to run the calc and include depreciation). I believe thats the best metric to see if it is a good investment.

I must save this for a years time to see real word numbers.

 

[ClubMan]

Kilowatt.ie has a pretty good modelling tool where you can upload your ESB data and show savings across all plans not just the one you are on

I found EnergyPal better to be honest.

EnergyPal.ie

Use smart meter data, visualise your energy usage. Take control of your energy costs with EnergyPal.ie! Compare and find the best energy plans based on smart meter data - all for free. Start saving money and optimizing your energy consumption today

www.energypal.ie

 

[FANTANA]

That is completely wrong as I've already outlined. You need to compare your usage against the most appropriate plan with/without solar/battery.

If I did the install of solar, battery and bought an EV all in one go that would be correct. However I have had an EV since 2020 and that doubled my electricity consumption per year immediately, that had me switch to a day night rate at the time.

I then added solar and switched to a smart tariff to avail of FIT and better EV rates.

Adding the battery I haven’t changed plans yet as the current plan I’m on is just being used more effectively.

Every time you upgrade your home you have have to reassess. By your logic I should ignore any upgrades I made and compare it a reality that no longer exists.

It would be like your triple glazed windows, say your boiler is twenty years old you upgrade the windows first and the payback on the windows looks better as your boiler was less efficient. Upgrade the boiler first the windows look less efficient. End of the day they both save you but by the laws of diminishing returns each upgrade saves less.

While we are on triple glazing if you put these on south facing aspect you will lose solar gains so they may lose you more energy than double?

You must take each upgrade as you do them as you have now altered your energy usage and can’t undo that.

If you moved home would you keep comparing to your last home, of course not, energy upgrades are like changing your home by small increments.

 

[Pawel Nowak]

A properly sized battery would allow you to use the ev rate so you'll benefit from paying between 9 to 6 cents depending on the provider. So in my case I was previously paying 33 cents per kWh on a regular 24 hour plan. So looking at December I've used 200kWh on the old plan this was coming up at 33 euro on the new smart plan it's 12 euro. I purposefully excluded the solar panel production for the ease of calculation.

 

[faketales]

You must take each upgrade as you do them as you have now altered your energy usage and can’t undo that.

I think your situation is unusual as most do solar and battery together.

It also looks heavily dependent on selling from battery back to the grid, the view of many seems to be that this will drop.

It also shows how complex it all is, with so many moving parts / uncertainty to predict.

 

[Blackrock1]

Had solar almost exactly two years before buying the battery, knew I’d get fleeced by an installer to put the battery in so just made sure my inverter was hybrid with the intention to add the battery myself later.

Fantastic you probably got 16kw for less than 5 from an installer, is there much to installing?

 

[Blackrock1]

That is completely wrong as I've already outlined. You need to compare your usage against the most appropriate plan with/without solar/battery.

You are only on the plan with a 35c day rate to make use of the battery and EV charging. Without knowing the details, you are probably saving something closer to €300 or less with your battery.

Still good but not even remotely close to a 2 year payback

completely wrong is a bit definitive. I have neither solar or battery at the moment, we have a HP and an EV so use about 14-15,000 units per year, best plan for me (as verified by the various tools ) is a D/N which i pay 13.5c and 27c give or take.

If i had a 16kwh battery and i diverted day usage to night it should save me circa 1.72 a day or 630 a year. Take 15% off (which i think is high) for days in the summer when i cant fully utilise the battery in a day (but would also charge less) its still around 535, you'd pay the battery back in 3 years.

 

[cremeegg]

Its maximum savings based on being able to use solar for every unit I use. That's unlikely.

Based on a 10 panel installation generating 3,500 kWh in a year
Each 1 kWh generated is worth 21.5 cents (using 30% at 26 cents, exporting 70% at 19.5 cents).

As you would know if you read through the thread.

If you have any sensible comment to make on that please share.

 

[FANTANA]

Fantastic you probably got 16kw for less than 5 from an installer, is there much to installing?

Bought the battery for €1400

Was very easy, three cables positive, negative and comms. Then a bit of playing around with the inverter settings using ChatGPT to sense check I was doing things right.

Hardest part was getting it up the stairs as it weighs 140kg. Had friends over at Christmas so asked them to help (before) we hit the beers!

There’s a picture to help visualise the set up.

 

[Duddaa]

Have a smart meter with two hours EV rate (9cent) from 0200-0400 so I charge my EV and battery during this window. I have night rate then from 0200-0800 (16 cent) and I tell it not to discharge during this period (as still cheap) then from 0800-2300 on day rate (33 cent) I tell it to take the load until it either runs out or if it still has power I tell it to force dump to the grid up to 0200 again as I get paid FIT 19.5 cent vs charging it at 9cent.

That's incredibly clever and organised. Was all that hard to set up? Is it an app or more a degree in computer science needed. This appears way more sensible that solar for people who can't put up solar panels. Apartment or protected building, etc.

 

[Micks'r]

While we are on triple glazing if you put these on south facing aspect you will lose solar gains so they may lose you more energy than double?

While solar transmittance will be lower for sure with tripple glazing, overall net heat loss will also be lower.

 

[FANTANA]

While solar transmittance will be lower for sure with tripple glazing, overall net heat loss will also be lower.

Ya true it was sort of in jest, guess I was just struggling with the concept triple glazing is a no brainer whereas solar was written off. I’d love to see the cost analysis of going from double to triple glazing coming out better than no solar to getting solar.

 

[peemac]

Based on a 10 panel installation generating 3,500 kWh in a year
Each 1 kWh generated is worth 21.5 cents (using 30% at 26 cents, exporting 70% at 19.5 cents).

Here's a first. I'm changing my mind.

Got a quote today of €8,250 net for 15 panels, 5.2kw battery and inverter. That's 3k lower than from another company last year.

Roof is directly south facing. They did the figures based on my electricity bill and my unit costs. They gave a 6.3 year payback and used 18c as the micro energy rate.

 

[peemac]

I’d love to see the cost analysis of going from double to triple glazing coming out better than no solar to getting solar.

I was advised today to replace seals on the windows and some hinges as a cheap quick improvement as I'm now going solar first and will look at windows in 18 months.

 

[cremeegg]

They did the figures based on my electricity bill and my unit costs. They gave a 6.3 year payback and used 18c as the micro energy rate.

How much energy did they project to produce?

 

[Pawel Nowak]

Peemac get more quotes.
I got 15 panels 6.4kwp with a 10kwh Dyness battery and a solis inverter in October for 8250 after the grant, ber included plus the added twist of old solar panel removal included in the price. Mitros was the crowd I went with and I can't fault them on anything.
I highly recommend joining the Irish Solar Owners Group on Facebook well over 70k members who are very much inclined to help you on your journey to get solar panels.