Solar Energy, anyone?

Forum about Domotica, home automation and saving energy.
Lennart
Member
Member
Posts: 497
Joined: Sat Jul 22, 2006 10:58 am
Location: Netherlands

Solar Energy, anyone?

Post by Lennart »

@snelvuur:

Search Google with "aparte groep 600 Wp" and you'll find some references to the 600 Wp limit. I think it's even in the new NEN1010 guidelines for domestic electrical installations.

And yes, solar panels are expensive; that's why they are being subsidized :-). Don't count on a free lunch from our government: if they give you 35 cents per kWh, it means that it will at least cost that much (but more likely a lot more :-) to produce... The price per Wp (Watt peak) is approximately EUR 5,- nowadays. In general, if there's no subsidy, it would take anywhere between 25 to 40 years (depending on your assumption concerning the electricity price increase throughout the years) to "earn back" your investment. With the subsidy this would become 10 to 15 years and in my opinion that would be acceptable. Note that the lifespan of a PV system is at least 25 years for the panels and approximately 10 years for the inverters.

Lennart
Bwired
Administrator
Administrator
Posts: 4704
Joined: Sat Mar 25, 2006 1:07 am
Location: Netherlands
Contact:

Solar Energy, anyone?

Post by Bwired »

Hi Lennart,
You might be right, but with current prices it's whole lot of money for a small percentage. Thats my problem with it. If I could buy them cheap like you did....... :-)
Thanks for explaining a lot on solar!
Digit
Global Moderator
Global Moderator
Posts: 3388
Joined: Sat Mar 25, 2006 10:23 am
Location: Netherlands
Contact:

Solar Energy, anyone?

Post by Digit »

@lennart:
It's good to have an "expert in the house"; Lennart, could you tell more about the most common problems with the inverters; they always seem to be the weakest link, right? Another question is, how much surface did you need for all your PV panels?
User avatar
Snelvuur
Forum Moderator
Forum Moderator
Posts: 3156
Joined: Fri Apr 06, 2007 11:01 pm
Location: Netherlands
Contact:

Solar Energy, anyone?

Post by Snelvuur »

Looks like 32 panels.. but since its a couple of years ago, we now see where he has the extra money for domotica from ;)

// Erik (binkey.nl)
Lennart
Member
Member
Posts: 497
Joined: Sat Jul 22, 2006 10:58 am
Location: Netherlands

Solar Energy, anyone?

Post by Lennart »

Hi Digit,

Yes, the inverters are the weakest link in most PV systems. As long as the panel (which is basically just a plastic laminate, a layer of silicium solar cells, a layer of glass and an aluminium frame) stays watertight, it will continue to work; it has no electronic nor any mechanical components. The inverters on the other hand contain a lot of electronics and - as we all have experienced - electronic devices will fail sooner or later.

I have probably been quite unlucky, but here's my track record of the past 5 years:

- Philips recalled their inverters *twice* because of - as they said - a fire hazard in the electronic circuit. I happened to have 5 of these inverters.

- Many early systems were equipped with NKF OK4E inverters. These inverters were mounted *outside* on the back of the panel. In other words: they supplied 230 AC directly from the panel on the roof into the house. These inverters turned out to be quite unstable. Reports mentioned failure rates of over 50% after a few years. NKF and solar panel suppliers (mainly Eneco, Nuon and the like) decided for a large scale replacement operation (> 10.000 installations!), having an installer replace the panel mounted inverters for a single Mastervolt Soladin 600 string inverter inside the house. I happened to have 8 panels with NKF inverters; they got replaced by 2 Mastervolts. Interesting detail: the NKF inverters had a "KEMA-keur" printed on their label, but they'd never been tested by KEMA :-).

- I have 5 Exendis Gridfit inverters. One of these had a strange alternating behavior: if solar radiation increased to a certain level, it would continuously reset itself. I had it replaced. The replacement inverter broke down (blown fuse?) within a month after replacement. I had it replaced a second time.

- I have 12 BP solar panels. They turned out to have a production defect that could cause the frame to become "powered", due to using the wrong sealant. I'm currently awaiting replacement panels (these panels are currently disconnected).

Although I must say that suppliers and manufacturers have been very helpful in getting these problems solved, at no cost at all, often paying for "lost" kWhs and sometimes even out of warranty, it's been quite a hassle to deinstall/install the failing components and arrange replacements. This equipment was definitely not at the consumer-grade level back in 2002/2003.

Don't let this story scare you though: I think things are better nowadays. Note that I have experienced only a single real malfuntion; the other incidents were preventive replacements and/or product call backs. And given the fact that almost all of my inverters have been replaced, they should last for another 10 years without any problems, right? ;-). That's at least what is currently seen as a reasonable lifespan of an inverter.

Inverters with a good reputation are:

- SMA Sunnyboy (several, also for larger systems)
- Mastervolt Soladin 600
- Stecca 300/500
- Exendis Gridfit

As far as your questions about the needed surface is concerned: it all depends on the way you place the panels. Usually, you would try to position the panels to the South, at an angle of 36 degrees; that would give you the optimal annual revenue. On a flat roof, this is easily done using PV mounts. However, if you put them at an angle, you need a certain amount of space between rows of panels, because the panels would otherwise be in the shadow of the rows in front. In general, given a flat roof of 100 m^2 (like you have), you would be able to place around 40 to 50 m^2 of solar panels. That would be around average 40 panels.

In my case, the situation is a little different. As I already had the panels, my intention was to place as many panels as possible, even if that meant that the position of each individual panel would not be optimal (I'd rather place 40 panels at 75% efficiency than 20 panels at 100% efficiency). Hence the more or less "flat" installation in line with our roof. This would in theory still be approximately 75% efficient. We now have 42 panels installed, taking up roughly 50 square meters (the main roof has 32 panels and is approximately 40 square meters).

Lennart
Esteban
Forum Moderator
Forum Moderator
Posts: 677
Joined: Sun Jan 13, 2008 6:39 pm
Location: Netherlands

Solar Energy, anyone?

Post by Esteban »

Thanks for sharing your experiences Lennart, this was very informative. I looked into solar energy before, but like Bwired, costs of installation make me cringe. How cool it would be, to stumble upon a really good bargain... that would basically 'make' you money ;)
Niknik
Member
Member
Posts: 255
Joined: Wed Apr 26, 2006 6:22 pm
Location: Portugal
Contact:

Solar Energy, anyone?

Post by Niknik »

I'm also very interested in solar systems... I hope the annoucement Google made a few months ago, that it would finance renewable energy investigation, and that company that started shipping low cost panels will make solar power advance a giant leap in the next few years.

Solar roofs should be mandatory in all new buildings. ;)
Hogeterp
Starting Member
Starting Member
Posts: 10
Joined: Sat Jan 19, 2008 10:49 am
Location: Netherlands
Contact:

Solar Energy, anyone?

Post by Hogeterp »

I found this in my e-mailbox(http://www.ecoxtra.nl)
Lennart
Member
Member
Posts: 497
Joined: Sat Jul 22, 2006 10:58 am
Location: Netherlands

Solar Energy, anyone?

Post by Lennart »

Here's a link to a site of someone doing what we'd all like to do with solar panels...

http://www.pv-solar24.info/

Lennart
User avatar
Snelvuur
Forum Moderator
Forum Moderator
Posts: 3156
Joined: Fri Apr 06, 2007 11:01 pm
Location: Netherlands
Contact:

Solar Energy, anyone?

Post by Snelvuur »

Very nice, now all we need is cheaper prices. But with the new "subsidie" you get money for every kwh you make, and thats beside the kwh you save on not having to use the power from the power company itself, and perhaps kwh send back to the net too right?

http://www.solarnrg.nl/terugverdien/tabelvoorbeeld.pdf <- nice table, is this correct? with the new 33cents deal?

// Erik (binkey.nl)
Lennart
Member
Member
Posts: 497
Joined: Sat Jul 22, 2006 10:58 am
Location: Netherlands

Solar Energy, anyone?

Post by Lennart »

Hi Snelvuur,

I don't think the table contains the new subsidy. Some observations:

- The table assumes an annual energy generation of 950 kWh/kWp. In Holland, this is more like 850 kWh/kWp, which makes the annual energy generation more like 3145 kWh.

- The table states a kWh price of EUR 0,16. This is currently more like 20 to 25 eurocents, depending on peak/off-peak tariffs and supplier.

- The table assumes an "other" pay back fee of EUR 0,45 per kWh. I don't know where this comes from...

- The tables assumes an energy price increase of 6% per year; I don't know how valid this is.

- The table seems to be based on financing through a mortgage construction, using tax deduction as an important "profit".

All in all: the basic calculations are probably ok, but the outcome will vary a lot depending on your assumptions.

Furthermore: I'm still not entirely sure whether the new subsidy allows you to use the generated kWhs yourself while still getting the subsidy. It's the subtle but very significant difference between a "generation subsidy" and a "feed in subsidy", which will make a 20 to 25 eurocents difference per kWh!

In general, given the new subsidy, investing in PV panels is going to be worth the effort. You will get your money back in the long run; how long will depend on the precise details of the subsidy but it will be within the lifespan of the system.

I'd say: wait for the details (they should be clear within a month or so). If they are acceptable, act fast! Subsidy is limited in both amount and time and given the 5 year stop on PV subsidy, everyone who has ever considered buying panels during the last 5 years might want to apply. If you are serious, I suggest you search for a suitable system (note that there's a minimum and maximum on subsidized system size, which seems to be 600 and 3000 Wp) and ask for prices quotes beforehand, so that you're ready to order if details become available. Note that the solar market in the Netherlands has collapsed during the last five years, so the handful of suppliers that's left will have a hard time keeping up with demand.

Lennart
Lennart
Member
Member
Posts: 497
Joined: Sat Jul 22, 2006 10:58 am
Location: Netherlands

Solar Energy, anyone?

Post by Lennart »

By the way, here's an impression of what PV panels do to your technical room :-). The 5 inverters on the back are Exendis Gridfit 250 inverters, each connected to 2 panels. The yellow/white inverter (consisting of 5 modules, each connected to 4 panels) is a Philips inverter (now Steca). The red one is a Sunnyboy 1700, connected to 12 panels (2 strings of 6). If you look closely, you'll see an RFXCOM temperature sensor as well :-).

Image

Lennart
User avatar
Snelvuur
Forum Moderator
Forum Moderator
Posts: 3156
Joined: Fri Apr 06, 2007 11:01 pm
Location: Netherlands
Contact:

Solar Energy, anyone?

Post by Snelvuur »

Ok, so i really want to give it a shot if the subsidy is a good deal. So seeing the above picture it looks like i need to place it in a different part of the house. The room for my ict part is big enough to do it i think, is it really so big, or is it just the picture you took? Can you make a picture to give an impression on how big it is in total if its not too much too ask.

I would assume i would need 3 fase then, can you just extend 3 fase from your fusebox towards the ict room and then a tube to the roof? I would think 1 tube is not enough going to the roof (i would think at least a bigger tube or 3 smaller ones?)

What i would have is a normal fuse box, and a seperate room for ict/PV stuff, and a roof. I would need to get cables from the fuse to the ict, and from the ict to the roof. Since the fuse box is pretty tiny, i dont know if its handy to put an extra 3fase part in there and then extend it to the ict room. What would you reckon?

// Erik (binkey.nl)
Digit
Global Moderator
Global Moderator
Posts: 3388
Joined: Sat Mar 25, 2006 10:23 am
Location: Netherlands
Contact:

Solar Energy, anyone?

Post by Digit »

Yeah,
the room looks big, but when i look at the PVC pipes i assume it is smaller then you'd think at first sight. Lennart, could you give some dimensions?

I still don't know what to do BTW; still struggling... i had other things in mind with the $$$$$ investment needed, on the other hand, it's what i have wanted for some years now, so pff....tough decision!
User avatar
Snelvuur
Forum Moderator
Forum Moderator
Posts: 3156
Joined: Fri Apr 06, 2007 11:01 pm
Location: Netherlands
Contact:

Solar Energy, anyone?

Post by Snelvuur »

Well for me its easy, i can put it in my mortgage and say its "house improvements" but since the house is in the building process i rather want to spend some money to have the first "pipes" allready there so i dont need to drill more lines or any other crap like that.

// Erik (binkey.nl)
Post Reply

Return to “Energycontrol & Home Automation Forum”