Going Solar
 

EDP, our energy provider have been trying to persuade us to install a solar system in our home.
The system that they recommend consists of 8 solar panels amounting to 16 sq mts, on the roof , and with a total output of 3.24 Kw.
Also included is a 5Kwh Battery. Although they admit that the system is not capable to provide all the electricity we require, it is expected to reduce our Grid requirement substantially, with a saving of around 600€ pa. Our current annual bill is around 1200 total pa. The buying back by EDP, of any surplus energy generated by the system would be compensated for, with a 10% discount on any additional Grid energy that we require but for the first 2 yrs only.
Potencia charges and the other addons do not change.
The cost of the system is 10,000€ payable up front or in 60/96 month instalments costing a bit more.
The contract includes 12 yr warranty on the panels and 10 yrs on the battery. Annual cleaning of the panels is included.

Solar systems have reduced in price quite dramatically over the past few years and I noticed that Leroy Merlin have 2 sq mtr panels costing 109€ each so 8 x 109 = 872 plus a battery and installation say another 4k comes to 5k tops ?
So comparatively, the EDP deal looks very expensive.
I,m wondering if anyone has gone for a EDP system, and if so how is it working out ?

Any/ all observations gratefully received !

Re: Going Solar
 

Absolute waste of money. Only interesting to tree hungers and zeros.
Based on rough cost you provided, it will take 16y before you see any return on investment. You would get better return by putting 10K in stock market for 16y, just saying.
Solar energy would only be viable if they could return on investment in 5y, none of it can do that today.

Double glazing used to be con of the day, things have now moved to solar hype.

Re: Going Solar
 

Surely, if the system could provide all that you require then it might make some sense, otherwise why bother, especially at that cost level?

Re: Going Solar
 

Well, my calculations are different; I don't have the numbers in front of me, but PV panels pay for themselves in about 8 years if they're sized for maximum benefit and oriented in an optimum manner (many are not).
That's assuming electric heating (heat pump) and a buffer so most heat can be made in daytime, calculated with Portuguese sunlight and Portuguese electricity prices.
Because I already have bi-horia rate, I can see how much I use in daylight hours. I can also see exactly how much heat I use now, and that is my basis for the numbers.

However, when a battery is added, the numbers don't come out very good. the battery costs more than the power it ever gives you, last time I checked.

So my conclusion was do not invest in the stock market until after you have PV panels on your roof; but there are a lot of variables.

It's very difficult to find someone to advise you, since they all want to sell you the material they like to sell. When I looked at the EDP offer, it was good; but it's even better for EDP. They get your excess power for free (or close to free) and sell it for 20 cents.

Re: Going Solar
 

Battery prices are dropping like a stone and in addition new solutions are coming which do not require complex installation.

Take a look at HOMEWIZARD which offers a lot of energy monitoring options as well as a new plug-in battery system which can be expanded as required.

Re: Going Solar
 

I have 16 solar panels on my rooftop terrace. In summer time, my electricity bill is practically zero. November and December and most likely January is a very different story. We've been around 300 per month.

Not sure where you live but it'll take a few years to recover your investment. I genuinely believe it's a waste of money and in 15-20 years you'll just be contributing to landfill when people finally abandon solar

Re: Going Solar
 

Of course all depends on your local conditions and prices, (I am in NL) . Even so the monitoring App and other accessories are a big help in seeing your actual consumption.
Gas prices went through the roof here and they lowered the electricity tariffs for sending back to the network plus in addition adding extra costs for returning your excess to the grid.
Hence the interest in doing more with the generated power rather than sending it back. One battery is about €1500,- , ROI 3 - 5 years.

Re: Going Solar
 

Solar panels pay for themselves pretty quickly if you can fully use all you they produce. It is very important to work out your yearly consumption during daylight hours before investing. I live in the North of Portugal and I have a 2.75kW installation that cost 3200 euros to install 3 years ago. I have a control system that charges solar storage heaters with solar production and have hot water and PHEV charging on summed excess power that pretty much minimises what I export to the grid for about 8 or 9 months of the year. I don't have a pool so I do export a fair but during the summer months with only PHEV using solar production up when I am at home. For 2024 my panels produced 3383kW of which I consumed 2682kW which @ 20 cents/kW plus IVA is about 600 euros. I exported 701kW to the grid which works out about 160 euros so having a battery would not be cost effective for me but I will keep an eye on prices. I got a 2000 euro grant from the environmental fund so my installation has already paid for itself. I don't know if grants are still available. I would say solar panels are here to stay and are a great investment.

Re: Going Solar
 

I think if anybody hasn't looked at solar electric in the last two to three years they'll find as with most developing technology they're very out of touch. As with most improvements there's no golden bullet, its lots of small improvements in all the elements.

Solar panels are now capable of generating greater power and also they can generate it at more oblique angles. The panels I now have are physically the same size as the previous generation but instead of generating 460 watts they generate 595 watts. Each panel has it's own optimiser (which is an extra cost) therefore, if part of the array on a particular string is in the shade it doesn't affect the whole string. Equally, inverters are now much more programmable with the ability to run three and even four strings. The arrangement of the panels is also important, You don't want them all facing in the same direction. I have six facing southeast and 12 facing southwest coupled to a 10kw inverter providing both single and three phase and an expandable battery pack currently with 14kw of storage. The price of batteries have reduced substantially in the last six months and of course if you have a full install (with or without batteries) the IVA is only 6%

The southeast panels give power immediately in the morning (after the batteries have run the villa overnight) and run the villa and the pool pump and give a small initial boost to the batteries. The southwest ones come up to full power from about lunchtime onwards to power the household and the 3 phase pool pump and fully charge the battery pack. Its important to try where possible to equalise the output of the strings and the best way to do this is to make a string where the panels are roughly in the sunshine for the same amount of time.

During the summer in Lagos with five air conditioning units running as well as the pool pump, the fridge freezer and general household electric for cooking etc the electric bill could go as high as 390 euros a month. With this set up its zero. In the winter the air conditioning units heat the villa.

The PV array is fixed to the roof, if it was free standing you can use a double sided PV panel and take advantage of reflected light from below, This would be great in Northern Portugal when you get a covering of frost or snow on the upper surface but the snow/frost on the ground reflects up to the lower surface and the power generated could be directed to either heat the panel to melt the upper surface, or provide power, or both.
A
The biggest problem with it all was as in all things Portuguese was the volumes of paperwork, it feels like it's the equivalent of war and peace three times over!

Its not for everyone but it works for us.

Re: Going Solar
 

That's interesting; I'd like to hear how it's working out economically, especially if you're able to work out if the battery is paying for itself.

Also, who did your installation, if you can recommend them to others in the area.

Re: Going Solar
 

Is the battery paying for itself is a difficult question to answer.

You have to look at when you would use the battery, the obvious answer is at night when the sun has gone down but if most of your use is during the day then is the investment worth it for a small reduction in mains cost for night consumption. On the other hand, if you use a lot of consumption on a night, air conditioning for instance then yes, a battery may be worth it.

You’re then faced with the question as to how much capacity you need. Typically, with expandable modules the first battery is the most expensive because it includes the base for the first battery unit and the top which houses the controller. Each subsequent battery costs far less because you’re only buying the basic battery pack and just sitting it in the tower. You then have to decide what size modules you want to build it from, for example 3kw or 5kw or as in my case 7kw. You can’t mix and match. Until you work out your anticipated and projected consumption you can’t work out how much capacity you need.

Equally, if you buy a pack with more than one battery (from a reputable manufacturer) the packs should be matched perfectly and will give a better output than buying one battery now and additional one/s at a later date.

You then have to look at how you’re going to measure the return, what happens during the day if you’re using the maximum from the PV panels, say several appliances and a three-phase welder and a cloud crosses the sun, if it seamlessly draws from battery pack rather than from the mains to make up the shortfall how do you measure this against the outlay.

If it’s a cloudy day and you still have spare capacity in the batteries and this makes up the shortfall from reduced output of the panels you need to consider this as well.

Another point to consider is, do you change your lifestyle to suit the power you have available, i.e you’ve had the benefit of charging the batteries all day so, do you start to consume power on a night (i.e. air conditioning) because there’s no add on cost but you wouldn’t if it wasn’t available from the batteries?

On top of all this you also have to factor in how many panels you need coupled with their output and orientation. If you can fit them all in given elevations with no possibility of shadow coverage you shouldn’t need individual optimisers and if you can do this for say two elevations, you’ll need an inverter with only two stings.

As you can see not an easy question to answer.

Re: Going Solar
 

I ask because I hear that batteries are cheaper, but I need a lot of convincing.
Especially after a "reputable" firm in my area told me a pack of lies about the economics of them (immediately going back on those claims after I asked for hard numbers).

So, 14kwh battery; if I buy a kwh from EDP, it costs 20 cents. So the entire capacity of your battery is worth 2.80. Lets say you manage to charge in daytime and then use at night 80% of that, 200 times per year, we get value of 560 euros per year; which is really pretty good.
If the battery lasts 20 years, which would be 2,000 80% cycles, that would amount to 11,200 euros. That does not include interest on the initial outlay, but actually we're leaving out all sorts of things. The charge controller and associated parts, the capital gains or losses on the equipment, future prices of electricity.

I don't know if those batteries do 2,000 cycles either; but you get where I'm going. This is the calculation that needs doing.
So, how many cycles does the battery maker claim, and what did the battery cost?

Another way would be to check your nighttime power use, assume a percentage that the battery would supply, and figure out if it costs less than the power bill.

Of course these numbers can also change in future; the price of electricity might go up, or could even go down (I doubt it though). The price of batteries could go either way.
There is also risk and reward in owning your own equipment, longevity of the panels, inverter, controler, and batteries is not sure, past the short warranty period.

Re: Going Solar
 

I feel as though I’m having to defend my decision to use batteries. As I said in my very first post it’s not for everyone. I have no vested interest in convincing people to use solar with or without batteries.

If you want me to comment, the warranty typically is 15 to 20 years on a battery pack. Your assumption is based purely on night-time usage. As I tried to explain, if its controlled correctly there can be an advantage to daytime usage when the PV panels are not producing at maximum, Also as I tried to allude to its not just using the batteries, its also making use of strategically positioning the PV panels to make use of the sunshine from sunrise to sunset not just at the peak times hence more strings and use of optimisers. This enables the panels to take every opportunity to charge the batteries even without full sun as well as providing power to the household. It needs to be a complete solution planned very carefully. By doing this I know you can achieve more than the 200 days you assume.

Just searching the internet there is currently a 15kw Huawei full battery pack (3 x 5KW batteries) available in Germany for 5,484 Euro’s.

I’ve no idea what your “reputable” firm told you about them, I was referring to using a reputable component manufacturer to provide a matched battery set, that’s nothing to do with the economics of usage.

I feel I’ve said all I want to say on this matter.

Re: Going Solar
 

I'm building a new villa in central portugal... There's an unobstructed flat roof 6 x 8.5 m - solar is the obvious solution, but also does anyone know if there are grants from https://www.fundoambiental.pt/ or others to assist with installing a reversible heating\cooling heat pump?
Given I'm not resident (yet) and its a new build it could be a stretch.
Haven't decided on batteries yet. Heart says go large on the new stuff, head says may not get my money back.

Re: Going Solar
 

Grants ended last November unfortunately - discontinued for 2025

Thanks everyone for the input , I think I will pass in the meantime. Perhaps the available deals may improve in future.

Re: Going Solar
 

Sorry, I didn't mean it like that at all.
I applaud your efforts and appreciate you sharing your experience.

It's very valuable to those of us who still need to make decisions about it all.

Re: Going Solar
 

Thank you for your comment I appreciate it.

One point I would make is users tend to view the effectiveness of batteries on their night time delivery. Based solely on that, then depending on the cost of the battery per KW it can appear to be a questionable expense.

As with most things, as I’ve already alluded to its more about the joined-up thinking of the complete system starting with the individual panel wattage generation. Secondly, its making sure the direction of them is optimised for maximum light capture throughout the whole day. A typical scenario would be, the battery depletes overnight but the following morning the sun is out and due to the positioning of some of the panels they immediately start generating power to the household and any excess starts immediately charging the batteries. As the day progresses there is some cloud cover but because of the early morning charge the batteries supplement the reduced panel output and later in the day when the clouds clear the panels return to charging the batteries while continuing to power the household including say a three-phase pool pump.

Given the correct number of panels and the correct installation of optimisers running in balanced strings there is normally enough daylight to fully charge the batteries and run the household on depleted sun (panels are not as dependent on full sunlight as they used to be).

In other words, providing a lot of thought is put in to the installation the measure of the battery delivery has to be taken over a twenty-four-hour period not just overnight.

The obvious question is, why aren’t all systems like this, the answer is quite simple, the cost and not enough space, users normally want the panels tucked up out of the way on the roof normally on a single elevation and secondly, it’s a lot more labour cost to spread the panels out, coupled with more panels and longer cable runs and extra expense in optimisers. Each panel needs it own optimiser at say 275 euro’s per panel plus an inverter that can handle more than the typical two strings. The inverters and extra strings are well worth it with or without batteries.

It does pay for itself especially given the number of days down here that are bright (as apposed to full sun) and the batteries probably make a contribution in the region of 260 to 280 days per year.

As I have said, it’s not for everyone and is an individual judgement call.

Re: Going Solar
 

We're completing some work on the house so the consumption is a bit erratic. We're not using power all day but in a way it helps to show the example clearly. I'm showing some screenshots below to show how the PV and battery work together to make sure there is still no draw from the grid.
https://cimg3.ibsrv.net/gimg/british...0e0fa09b73.png
The graph above shows the house consumption with a peak between 12.30 and 14.30.. The battery (in purple) shows the partial supply to power the house because there was no substantial PV output.
https://cimg4.ibsrv.net/gimg/british...649942d383.png
This graph shows when the sun was out and it powered the house and allowed the battery to switch off.
https://cimg2.ibsrv.net/gimg/british...361ee6f09d.png
This graph shows the PV charging up the battery. The morning peak was when the sun was out and it fully recharged the battery from overnight use. The later peak shows the PV fully recharging the batteries from the daytime use back to 100% ready for the overnight use again.

I've posted this to show when working out the cost efficiency of batteries you just can't calculate it on overnight usage.

Re: Going Solar
 

That's really cool.
It would be interesting to see the different graphs and total panel and battery output after a year or so; maybe it would be possible to separate and work out how much the panels and battery earned for you.

Of course everyone will have different usage patterns.

Re: Going Solar
 

You're right. Ive installed PV and battery systems in my houses in UK and Portugal, and in my camper van. As you say, 540Wp panels are just over EUR 100 at Leroy-Merlin. I think 5kWh batteries are about EUR 1500 just now. The inverter will cost about EUR 1,000. Cables, AC isolator, mounting for panels will be about EUR 500 depending on how you do it. So, for 8 panels, about EUR 4,000 plus installation labour, which is very little - two semi-skilled guys for a day, or do it yourself. The rest of that EUR 10,000 is their profit. Doing it this way you probably wont be selling your surplus power, but thats not a big loss, as they only offer to buy for 2 years, and with a battery and correctly sized system you wont have a lot of unused generation. Personally I would go for 10 panels and an 8 or 10kW nverter; one or two 5kWh batteries. You can always add more later. They are the expensive part.

Re: Going Solar
 

IVA on components is set to rise from 6% to 23% at the end of June, unless the government jumps in with an extension to the low rates.
So for ditherers like me, it's time to get to it!

I was just checking on various bits; 600w panel from "obras360" (who I have bought material from in the past) is 80 Euros (!!!) This is so cheap that it's difficult to imagine that prices on this part of the system will drop much further, if at all. The panels used to be the expensive part, now they're the cheapest part of the system.
Inverters are coming down but slowly; battery costs continue to drop so it's hard to say whether it's time to buy them now or not.

Regarding the question I asked earlier in this thread about the economic viability of batteries at today's prices; it's still hard to pin down, but they now come with a 10 year warranty and supposedly will live through 6,000 cycles. That would be around 4 cents per kwh.
So, correctly sized, I think the answer is a yes.

Installers are all booked out (of course), however, you can make the invoice and pay the bill before the work is done, if you dare.

Re: Going Solar
 

Also worth a mention; the IVA rate of 6% also applies to heat pumps and air conditioners (which are actually the same thing), until the end of June, when it goes up to 23%.

Re: Going Solar
 

I got my panels and heatpump system just before the tax increase deadline. I did not but the battery or electronics yet.

https://cimg2.ibsrv.net/gimg/british...4c3742602e.jpg
https://cimg3.ibsrv.net/gimg/british...a19afb90a1.jpg
https://cimg4.ibsrv.net/gimg/british...6ffa47834f.jpg

Re: Going Solar
 

Is that an "ATLANTIC" heat pump system?..they are excellent! Sometimes they can be a little noisy at the intake/exhaust ports so route them to a place where that won't be an annoyance. (That's if you are running it as a standalone system).

Re: Going Solar
 

It's Samsung AE120RXYDGG... 3-phase 12kw output. I wanted a major brand that I could self-instal and they had a good price.

It came with a lot of bits and pieces, electronic sensors and controls. There's also a 100 liter buffer tank and a 300 liter domestic hot water tank.

So when the sun hits the massive solar array, everything can heat up. It's sized to work in winter, which means there will be a large excess in summer.
The bureaucracy is high, and the returns low for grid injection, so I'm not going to bother with that.

One guy I know makes hydrogen with his excess solar power. It's an idea; but I'm always waiting to hear an explosion from his place.