Solar Power

Old Apr 7th 2016, 9:21 am
  #46  
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Default Re: Solar Power

Originally Posted by Munsterfan
Our neighbor has a very smart set of Pv panels and Solar water heating system which has been in place several years. This system heats his pool and house water and generates electricity. It's a very cool efficient system. He did his research bought carefully and searched until he got a reasonable price for installation.

The downside is that unlike Germany and other 'smart' countries he can't sell his excess electricity bank to EDP (or other). Portugal is not buying electricity. If they did then his home would be virtually cost free and even generate income. I have a EDP pamphlet in my sweaty little hands here on the desk informing all solar homes generating electricity that they will accept the 'excess' BUT no offer the BUY it.

The other challenge is the lack of affordable 'deep house' batteries. If you amortize the retail current cost of purchase, shipping, installation creating a safe space to store these batteries you don't get a reasonable ROI until after the life of the battery is spent.
After reading this thread we did the math last night.
And so it goes in Portugal at the moment. If purchasing the excess electricity generated comes into being then we'll all be pig-solar-heaven. From My-Lips-To-Gods-Ears
Agree - local storage of electricity is high cost and beset by issues, so only by feed-in and an offset on prices does PV become a practical investment. However, I thought that whilst with smaller installations with no feed-in tariff agreed, power over 1.5kw is dumped back to the grid for no payback, you can agree a feed-in tariff for larger PV sytems ..... Last time I looked the compensation for the injected solar energy was 90% of the Iberian energy market price, so could offset nicely against grid usage.

On the other hand, solar water heating should be a no-brainer here in Portugal ..... but it's not hands off. Unfortunately the systems can be expensive and not all installers know their stuff, so there are many sellers (and buyers) of magic beans.

As Liveaboard has indicated on various occasions, the panel angle of incidence for solar collectors is an issue as most installers just put them at about 30 degrees which is a lose-lose here - too much exposure in Summer and not enough in Winter. Then they add in the "useful" automatic electric backup and people don't seem to realise they are still paying to heat water!

When I discussed my proposed wood-fired C/H and solar water installation, one "engineer" wanted to install two totally separate systems - and I had to insist on a dual-coil water cylinder to accept input from the wood-fired system. Then, when I told him that I estimated the optimum angle for the solar collectors to be about 57 degrees, he looked at me as if I was mad ..... and finally, when I told him I was not prepared to have them looking like pig's ears to point due South, he could not accept that the drop in efficiency would be no more than 20% ..... for him it was South or nothing. So much for experts - left to him I would be paying for an ugly, inefficient and wasteful system that would probably cost me more to run than the existing gas heaters!

So, check any previous installations and don't presume that the installer knows everything and will provide the best system for you .... as always, caveat emptor.
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Old Apr 7th 2016, 9:44 am
  #47  
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Default Re: Solar Power

Originally Posted by macliam
Agree - local storage of electricity is high cost and beset by issues, so only by feed-in and an offset on prices does PV become a practical investment. However, I thought that whilst with smaller installations with no feed-in tariff agreed, power over 1.5kw is dumped back to the grid for no payback, you can agree a feed-in tariff for larger PV sytems ..... Last time I looked the compensation for the injected solar energy was 90% of the Iberian energy market price, so could offset nicely against grid usage.

On the other hand, solar water heating should be a no-brainer here in Portugal ..... but it's not hands off. Unfortunately the systems can be expensive and not all installers know their stuff, so there are many sellers (and buyers) of magic beans.

As Liveaboard has indicated on various occasions, the panel angle of incidence for solar collectors is an issue as most installers just put them at about 30 degrees which is a lose-lose here - too much exposure in Summer and not enough in Winter. Then they add in the "useful" automatic electric backup and people don't seem to realise they are still paying to heat water!

When I discussed my proposed wood-fired C/H and solar water installation, one "engineer" wanted to install two totally separate systems - and I had to insist on a dual-coil water cylinder to accept input from the wood-fired system. Then, when I told him that I estimated the optimum angle for the solar collectors to be about 57 degrees, he looked at me as if I was mad ..... and finally, when I told him I was not prepared to have them looking like pig's ears to point due South, he could not accept that the drop in efficiency would be no more than 20% ..... for him it was South or nothing. So much for experts - left to him I would be paying for an ugly, inefficient and wasteful system that would probably cost me more to run than the existing gas heaters!

So, check any previous installations and don't presume that the installer knows everything and will provide the best system for you .... as always, caveat emptor.
In the early 80's I was working in Greece, even then NO Building would get a Licence or Permit to be used /occupied with out system to heat water installed & working.
I have no idea if this reg is required here in PT ,but my guess is it's not !!!
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Old Apr 7th 2016, 10:34 am
  #48  
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Default Re: Solar Power

We have not seen any new villas or aprtment complexes in the Algarve that do not have solar water heating systems installed.
We gave been told that they are mandatory.
There are also an increasing number of solar pv farms , on large holiday developments, water treatment plants etc..
We have a solar water panel and if we need to use the electric back up it is only for a few hours in the shortest cloudiest days of winter.
I will check the angle and inclination of our panel.
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Old Apr 7th 2016, 11:30 am
  #49  
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Default Re: Solar Power

Originally Posted by EMR
We have not seen any new villas or aprtment complexes in the Algarve that do not have solar water heating systems installed.
We gave been told that they are mandatory.
There are also an increasing number of solar pv farms , on large holiday developments, water treatment plants etc..
We have a solar water panel and if we need to use the electric back up it is only for a few hours in the shortest cloudiest days of winter.
I will check the angle and inclination of our panel.
I'm in the Alentejo, so don't see so much new build.

PV makes sense if you have a specific constant daytime usage for it, it's the storage, night-time use, high-demand usage, etc. that makes it less useful for general usage.

Does your water system dump water in the summer? Or do you cover the panel? If so the angle might be wrong..... and you'd be best changing it. However, I erred in my post as the optimum angle for my collectors is 52.5 degrees, not 57

The formula I used was:
Median angle equals latitude (so for me 37.5 degrees).
Then Summer/Winter variance is 15 degrees from median, so Winter angle would be 52.5 degrees.
Due to southern summers, the lesser efficiency during those months is likely to be offset by the longer, brighter days, so maximum Winter efficiency as a first step.
Supposed loss of efficiency facing East or West rather than South, about 20% - so a lesser offset from due South will be less
- and, of course, you could always increase the collector area to compensate.

That's the theory........ now for the practice
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Old Apr 7th 2016, 11:51 am
  #50  
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Default Re: Solar Power

Originally Posted by macliam
I'm in the Alentejo, so don't see so much new build.

PV makes sense if you have a specific constant daytime usage for it, it's the storage, night-time use, high-demand usage, etc. that makes it less useful for general usage.

Does your water system dump water in the summer? Or do you cover the panel? If so the angle might be wrong..... and you'd be best changing it. However, I erred in my post as the optimum angle for my collectors is 52.5 degrees, not 57

The formula I used was:
Median angle equals latitude (so for me 37.5 degrees).
Then Summer/Winter variance is 15 degrees from median, so Winter angle would be 52.5 degrees.
Due to southern summers, the lesser efficiency during those months is likely to be offset by the longer, brighter days, so maximum Winter efficiency as a first step.
Supposed loss of efficiency facing East or West rather than South, about 20% - so a lesser offset from due South will be less
- and, of course, you could always increase the collector area to compensate.

That's the theory........ now for the practice
From experience, panel seals blowing we now cover from May onwards when not there.
I am able to alter the angle a few degrees which I do summer,winter.
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Old Apr 7th 2016, 1:15 pm
  #51  
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Default Re: Solar Power

Originally Posted by EMR
From experience, panel seals blowing we now cover from May onwards when not there.
I am able to alter the angle a few degrees which I do summer,winter.
So, it sounds like putting the collector at its "Winter" inclination could benefit you....... it's a one-off change. Good luck!
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Old Mar 8th 2017, 6:40 pm
  #52  
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Default Re: Solar Power

Hi all, just picking up on an old thread. Looking at solar water systems and also possible PV electric. Read earlier stuff and am looking at the system Leroy Marlins have for the tank in the attic and panel on roof. Also interested in the offer that EDP have at the moment which, for 4 panels, is 64 euros a month for 3 years then it's paid off. Plus 10% discount on night rate. Problem is that they don't declare, or I can't find on the site, what the output is. Anyone got any experience with an EDP installation?

Also, house orientation. Our roof, simple pitch, faces east to west, so the panels would need to be either east or west facing. Pitch is probably 30 degrees or so. Would it be better to put a panel each side to catch sun all day or would it be enough to face them all one way?

Options welcomed with thanks. J
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Old Mar 8th 2017, 7:30 pm
  #53  
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Default Re: Solar Power

Best option is to place panels on both East and West roof facing. NB. You will not generate the same amount of power in this manner as you would if the panels were facing South.
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Old Mar 8th 2017, 7:34 pm
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Default Re: Solar Power

Curiously enough, I was looking at it today too and requested an emailed simulation/proposal from EDP. The panels are 260W nominally and are, I assume, each fitted with a micro-inverter.

Last edited by RichardHenshall; Mar 8th 2017 at 7:39 pm.
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Old Mar 8th 2017, 8:20 pm
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Default Re: Solar Power

Thanks Richard, maybe I'll approach them for a simulation too. But from what you said 4 panels will give about 1kWh during daylight hours. Doesn't really seem worth the bother or am I missing something. Payback would be years at that rate.
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Old Mar 8th 2017, 9:48 pm
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Default Re: Solar Power

Originally Posted by nogard
Best option is to place panels on both East and West roof facing. NB. You will not generate the same amount of power in this manner as you would if the panels were facing South.
That would seem obvious but others disagree. See

https://www.sunpump.solar/solar-pane...st/west-debate


The plot thickens
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Old Mar 9th 2017, 8:53 am
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Default Re: Solar Power

Originally Posted by Jonny22
Thanks Richard, maybe I'll approach them for a simulation too. But from what you said 4 panels will give about 1kWh during daylight hours. Doesn't really seem worth the bother or am I missing something. Payback would be years at that rate.
Depends how carefully you buy your initial equipment but it is possible to shop around and buy panels that give you a cost per watt of around 50/60 cents. So if you are paying €600 for your 1kw array + the cost of the inverter at say €250 then the project cost if you do most things yourself is retrievable quite quickly.

With EDP cost of 1 x Kwh at 20 cents you should conservatively get system payback in under two years.

It would be very interesting to know what the figures are on an EDP simulation - if you get one please post the info
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Old Mar 9th 2017, 11:02 am
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Default Re: Solar Power

The basic prices (inc IVA) for the EDP offering are:

1 painel (260 W) 720,00 €
2 painéis (520 W) 1.296,00 €
3 painéis (780 W) 1.800,00 €
4 painéis (1040 W) 2.304,00 €

all payable in equal instalments over 36 months.

Somewhat more than 50-60¢ per watt.
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Old Mar 9th 2017, 4:49 pm
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Default Re: Solar Power

http://www.buypvdirect.co.uk/PV_Panels

250w panels about €150 each but you would need to get them shipped from UK
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Old Mar 9th 2017, 6:10 pm
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Default Re: Solar Power

Before you purchase solar panels, consider the "Tesla option" and have a battery backup.

I looked at it for a house in the 🇬🇧 but the payback was 10 years (the same as their product guarantee). But higher prices for electricity and more sun may make it an option.

I have one house with 2kw on east and 2 on west, and it produces just less than my other which is 3.2kwh and faces south.

The other thing to consider is older electric meters go backwards, so unwind the electric you used last night. The newer meters have backstops to prevent this. Maybe a reason NOT to have EDP install them

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