How much are Solar Panels worth

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cremeegg

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When considering an investment in solar panels you are bombarded with info and it can be difficult to see the wood for the trees.

I have finally resolved to my own satisfaction the correct question to ask, and it is this, ‘how much are solar panels worth’.

The answer is actually quite simple, how much power will they generate in a year, your installers will give you an estimate, you can create your own estimate here https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html.

The answer for 10 panels in Ireland will come out about 3500 kWhr in a year.

What is each kWhr worth. If it replaces a purchased kWhr then the answer is about 35 cent. That’s €1255 a year. Discounted at 6% is €21,916.

10 solar panels are worth €22k. This is much less than they cost.

I would be glad of any comments on the methodology or the estimates.
 
I appreciate your estimate. We had our system installed at the end of October, 15 panels with a total output of 6.4kwp (South facing) and a 10kwh battery with 9.5 kwh of useable capacity.
So far we produced a little over 800kwh our FIT is paying 25 cents per kwh.
The biggest difference at least in the winter comes from utilising time of use smart tariffs to charge the battery and shifting most of our energy use to the cheapest rate.
I'm usually running my dishwasher and laundry on the cheapest tariff courtesy of delayed start function.
Which also means my battery never runs out until the next charge it takes a bit of tinkering but from my estimates using energypal and killowatt.ie my pay back is a little over 4 years. Any price increases may speed up this process significantly.
 
I’m a bit confused by the language in your last few paragraphs, but just some comments.

My 14 panels made 5900kWh in 2025, so 10 panels south facing might be more like 4200kWh.

But the value you’re putting on those kWh’s is a bit steep. Realistically you will not be able to use them all, so you’ll end up exporting at least half for more like €0.20-€0.25. This will increase over time of course, so for a ten year calculation you might say €0.25 initially going up €0.01/annum.
 
@cremeegg

Interesting approach, but what about things like labour, fittings, cables, the inverter etc., are they all included in your calculation?

I think you've got the estimate of 3,500kwr pretty much spot on, btw...
 
Zenith63 said:
Realistically you will not be able to use them all, so you’ll end up exporting at least half for more like €0.20-€0.25. This will increase over time of course..
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I would say more likely that over time the Feed In Tariff will be abolished. The electricity generating potential of the panels will also somewhat reduce over time.

The main thing that can be relied on is every kilowatt of electricity the panels generate will save you more and more money over time because you didn't have to pay for them.
 
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Zenith63 said:
My 14 panels made 5900kWh in 2025, so 10 panels south facing might be more like 4200kWh
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MrEarl said:
I think you've got the estimate of 3,500kwr pretty much spot on, btw
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My own panels are a bit east of south so directly south facing may achieve more than the 3500 I mentioned.
Zenith63 said:
But the value you’re putting on those kWh’s is a bit steep. Realistically you will not be able to use them all, so you’ll end up exporting at least half for more like €0.20-€0.25.
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This is a fair point. I will be unable to use many of the kWhrs generated myself and they will have to be sold back to the grid. I get 19.5 cents for my feed in tariff. To date I have sold 53% of my generation to the grid. It is likely to be more in summer.

Is 70% going to the grid over a full year realistic, how can I improve on that?

70% at 19.5 cent and 30% at 35 cent is 24.1 cent average is €845 per annum discounted at 6% gives a value of €14k for 10 panels.

So my valuation of 10 panels has reduced because the value of each kWhr produced is less than I thought. It is still much less than the cost.

(Btw I have deliberately avoided any mention of a battery, that will be my next question. I want to tease out each separately before looking at them together)
 
cremeegg said:
Is 70% going to the grid over a full year realistic, how can I improve on that?
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We sent 50% to the grid for 2025. However we have two electric cars that are often plugged in during the day to use any excess solar. We have a house battery too but it’s set to charge over night and discharge during the peak time at 5pm, so it’s not storing any excess solar generation. So 70% could be about right yes.
 
Zenith63 said:
We have a house battery too but it’s set to charge over night and discharge during the peak time at 5pm, so it’s not storing any excess solar generation.
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@Zenith63 Can you explain this? Sorry if it's a dumb question. I don't know what you mean, the battery charges overnight?

I have wanted to evaluate if it would be worth getting a battery. I already have panels which generate more than we use. But we don't have an electric car and other than running the washing machines overnight to use up power stored during the day, I'm not seeing what benefit we would get from a battery. But I'm have not researched the topic so my knowledge is poor.
 
You can configure the battery to just soak up spare solar generation and let the house use that when the sun goes down. But another option is to configure it to charge up at night from the grid (when electricity costs €0.14/kWh) and then let the house use it during the day (to offset electricity that costs say €0.28/kWh). This nets you €0.14/kWh, whereas storing excess solar and using it later is only netting you €0.08/kWh (your electricity provider will pay you €0.20/kWh if you export electricity to them). This also works every day of the year whereas soaking up spare solar generation is only really an option for a few months.
 
cremeegg said:
What is each kWhr worth. If it replaces a purchased kWhr then the answer is about 35 cent. That’s €1255 a year. Discounted at 6% is €21,916.
10 solar panels are worth €22k. This is much less than they cost.
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It is not clear what you are trying to say here, can you rephrase. Are you trying to say that it cost you (random figure) €10k to install but their value to you is €22k?

Aside from that, it's actually much much simpler to evaluate the return from a solar investment but pretty much every example on AAM gets it wrong. Nobody in their right mind would pay 35c for a unit if they didn't have solar so you should never use that figure as what you solar is saving for you.

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.

So many people will only look at the unit costs of the plan they are on (Plan B) and use those unit rates to calculate their saving but it makes no sense. You would never be on the tariff unless you had solar. Anyone claiming payback of less than 7-8 years is usually doing it wrong

I hadn't realised this until recently but Energy Pal (version 5) have added a solar and battery simulator to their calculator: https://www.energypal.ie/v5/

To illustrate, I've used my own HDF where we use 6750kWh per year (all electric, A-rated home with Heat pump). The current recommended plan is €1812. If I add the 3500kWh of solar, my total drops to €1057 from a different supplier. So your 10 panel set up would save me ~€750 or be worth 21c per unit to me. At no point am I saving the 30c peak rate from the plan with solar included.

Ultimately it needs to be your specific usage pattern with your solar input comparing the best plans for with & without solar generation. The Energy Pal simulator is excellent for this and will allow you to tweak lots of paramaters to match your own pattern.
 
cremeegg said:
Is 70% going to the grid over a full year realistic, how can I improve on that?
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2 year calculations from West Cork, 10 panel 4.15 kWh system with battery (battery recharges to full before any electricity is exported).

2024: Total PV generated: 3400 total exported. 2550 = 75%
2025: Total PV generated: 3565 total exported. 2800 = 78.5%
 
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If it helps, we have a 10 panel, 4.3kWh system with no battery. Made our best attempt to do wash cycles during the day when the panels were producing. If I was a home worker, I might also have held my morning shower over for a couple of hours to utilise solar generation later in the mornings!
For last year, we substituted 1,769 units of imported electricity with our own PV generation, saving us E421.28 on our bills last year. We also exported 2,393 units to the grid in 2025, earning E466.60. So our return in 2025 (our first year of monitoring) was €888 and the panels generated 4,161kWh. The net cost of installation (2023) was c.E6k.
 
_OkGo_ said:
Are you trying to say that it cost you (random figure) €10k to install but their value to you is €22k?
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I am trying to estimate the value of (10) solar panels I am saying nothing about the cost to install.

I started at €22k but thanks to @Zenith63 pointing out that most of the power generated will be sold back to the grid at a lower price I have revised my estimate of the value down to €14k.
_OkGo_ said:
Nobody in their right mind would pay 35c for a unit if they didn't have solar so you should never use that figure as what you solar is saving for you
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Fair point.

The typical unit rate on a flat rate plan appears to be more like 26 cent.
cremeegg said:
70% at 19.5 cent and 30% at 35 cent is 24.1 cent average is €845 per annum discounted at 6% gives a value of €14k for 10 panels.
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So I recalculate this as 70% at 19.5 cent and 30% at 26 cent on average thats 21.5 cent a kWh (assuming 3,500 kWhr per annum) is €751 discounted at 6% gives a value of €12.5k.

A lot less that where I started, but still good.
 
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Marsupial said:
2 year calculations from West Cork, 10 kWh system with battery (battery recharges to full before any electricity is exported).
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Thanks for this very valuable info.

I was trying to standardise at 10 panels. Does '10kWh system' mean you have 20 plus panels. Generating 3,500 kWh in a year from that seems very low, about half what I would expect.
 
rob oyle said:
we have a 10 panel, 4.3kWh system . So our return in 2025 ... the panels generated 4,161kWh.
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In terms of energy produced this is in line with myself @Zenith63 and @MrEarl.
rob oyle said:
For last year, we substituted 1,769 units of imported electricity with our own PV generation, saving us E421.28 on our bills last year. We also exported 2,393 units to the grid in 2025,
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So you exported 53% of the power you generated. That's a little better than the 70% I had estimated, and is that without an electric car ?
 
cremeegg said:
I was trying to standardise at 10 panels. Does '10kWh system' mean you have 20 plus panels. Generating 3,500 kWh in a year from that seems very low, about half what I would expect.
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:eek: Shocking error by me, apologies.

I have 10 panels, west facing, each generating up to 0.41 kWh (on paper, although up to .44 each in real life!) so the system spec is 4.1kWh.
 
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