Photovoltaic power?

Gurgle

I've been researching solar panels for electricity, and tbh I'm wondering if I'm missing something.

The best price per watt I've found is a 215W panel for €1600.

An installation of 3 x 215W panels would generate approx 2.5kWh per day, with an average of 4 hours of effective peak sunlight per day (Erring strongly on the side of optimism here), costing €4800.

Then you need a battery.

A 3500Ah battery, (oversized to comfortably handle the power) will cost about €1800.

A charge controller to match this array is around €300.

A 3kW invertor is about €2400.

Total price for components: €9300

Imagining for a moment that this was the total cost of the system, you could install it yourself for free, no extra components to phase-match to the grid.

If you get 2.5kWh per day, all year round here in sunny equatorial Ireland, thats 912.5kWh of electricity per year.

912 kWh costs €132, if you're just on the standard 24 hour rate of 14.45c per kWh.

Assuming, again with blatant optimism, that the components will last forever.

Total payback time:

*drumroll*.....


70 years.

wtf?

For a system that would be doing well to last 20 years?
Why would anyone even consider installing these things?
Have I couted euros instead of cents somewhere along here?

fishdog

You are quite correct. That does not mean that solar power is no good, it means that it does not suit some applications.

It is great for heating water for example. A few hours sunlight can heat alot of water, even on a cool day. I am trying to paste a picture here of some that I have installed, but I am not much good with a computer!

On the other hand I found an application that suited photovotatic cells. An intruder alarm system was required on a building site that had no mains power at the time. Intruder alarms work off 12V dc and require very little power to operate. No inverter is required and when there is no sunlight the panel works off its own battery. Panels cost €20 each in Maplins, and I needed 4. Very cost effective.

Gurgle

fishdog wrote:

You are quite correct. That does not mean that solar power is no good, it means that it does not suit some applications.

It is great for heating water for example. A few hours sunlight can heat alot of water, even on a cool day. I am trying to paste a picture here of some that I have installed, but I am not much good with a computer!

On the other hand I found an application that suited photovotatic cells. An intruder alarm system was required on a building site that had no mains power at the time. Intruder alarms work off 12V dc and require very little power to operate. No inverter is required and when there is no sunlight the panel works off its own battery. Panels cost €20 each in Maplins, and I needed 4. Very cost effective.

I completely agree.
Using renewables is great in general, save the planet and all that.

Solar water heating panels pay for themselves in 10 - 15 years, PV arrays are ideal where a grid connection is unavailable, e.g. if you want power in a shed down the fields somewhere.

But there seem to be loads of people/companies trying to pimp PV installations as a great way to reduce your ESB bill. I was dubious about the payback figures, had a vague feeling they were being fudged a bit to reduce the payback time. Turns out they're not just fudged, they're complete fantasy.

I never looked into it in detail until yesterday, someone asked me to price an installation.

I'll get back to him tomorrow and recommend a diesel generator.

fishdog

I think that the trick is to use more energy efficient electrical appliances and lighting to reduce your bill. Remember anything to do with heating something electrically is going to be expensive. Generally anything electronic (computers, TV, sound system etc.) is going to be cheap to run.

For example LED lighting seems to be a great way foward, they are cheap to buy, very cheap to run and will outlast most electric bulbs.

Capt'n Midnight

PV is only worth it here when the power requirement is so low that the cost of connection / standing charge cost far more than the electricity.

PV have one huge advantage over other ways of generating electiricity, a sealed unit will continue to produce power for years - no moving part. no air supply needed, ( the only thing that will beat it is a Radioisotope thermoelectric generator, which will give you power 24/7 for a couple of hundred years ( design life is about 10 years so probably best to recycle it then ) . Then again Plutonium is a tad more expensive than Gold and there is still the possibilty the PV cells might out last the thermocouples. )

Mixing PV and wind is interesting as they should compliment each other, but you would have to cut back on all electrical usage - laptops instead of desktops, LCD TV instead of CRT, LED light, and white walls. If you are paying 9 grand for a system that procuces 2.5KHw you might as well spend 4 grand on stuff to reduce your power needs to what a 5 grand system will supply.

You could cut the cost down a lot if you went for a "homebrew" system by simplifying the system. Instead of an expensive invertor perhaps a second hand UPS ? eg: APCC 3000 UPS - and external battery pack for it. You would run devices directly from it instead of wiring into the mains. ( KISS ) You'd rely on the UPS to handle various voltage levels on the input but the battery capacity would be minimal ( maybe you could use other batteries - not sure how you would wire in - or several external boxes and switch them over ) The 3000 VA would handle any power but would exhaust the batteries in about 6 minutes :rolleyes: but would supply 200W for 3 hours ( and an additional 3 hours for each battery pack ? )

http://www.freerepublic.com/forum/a3ab928b76932.htm - a backup generator for 100W - though if you want to push it I'd suggest you divert some energy into a cooling fan since that seems to be the limiting factor

http://www.apcc.com/products/runtime_for_extendedruntime.cfm?upsfamily=165

In our climate I wonder would PV cells ever generate as much power as it took to make them ?

fishdog

Interesting idea. But here are the problems that I see:

1 Batteries can only be recharged so many times

2 They are big, expensive and heavy.

3 It would take a long time to see a return on your investment

I think your idea about using equipment that requires less power makes much more sense.

air

Hi,
Just a few points on your proposed system.

1. Your proposed battery bank is waaay too big (assuming 3500Ah at 12v its 42Kwh). Budged for 3x your max energy harvest per day or about 8Kwh approx.
That would mean a 600AH bank at 12v approx which might cost in the region of 1200 euro. I dont know where you got your bank costings.

2. A 3Kw inverter is way too big for the size of the system.
A 1Kw one should be more than sufficient and you should be able to get a high quality pure sine one for around 700 euro.

3. Include standing charges etc in your cost per unit of grid electricity.

4. Your batteries might need replacing after 20 years but your panels shouldn't. The first pv cells produced are apparently still producing power.

5. You should be able to get the panels substantially cheaper than that if you use ebay etc.

Overall though, wind is still a much more viable option for anyone with a suitable site in this country.
Solar has its strengths though, these have already been mentioned.

riccol1966

May I comment on this, as I actually have a PV/Wind system in operation. Still working out the actual cost savings, but currently they are in the region of EUR10 per month, based on a combined 900watt system. Once the system is at its full capacity (hopefully 800w wind + 800w solar, total: 1.6KW) and I have completed all my tests, I will expect to save appx EUR13-15 per month.

But PAYBACK is not the reason to do this, so the originator of this thread is correct in saying it would be mad to consider such a system IF payback is a concern. For me it is not, but having parts of my house "off grid" certainly was a requirement, so that every time the ESB cut the power I can continue to work the PC, TV, fridge etc. And even with a generator it was still awkward to do, but not any more. No, I am not a hippie, I just want some independance from the GRID and am happy to pay for it.

I am also getting solar tubes to heat hot water; again NOT becuse they pay back but because it is greener to do so and I want to harness even more power from the SUN. OK, so they will pay me back, great, but that would not have deterred me in the first place.

BTW: If you are focusing purely on costs, ESB costs are 16.3 cent per unit; higher still if you add on a % for the standing charge.

Richard.

http://www.richardcollins.net

ircoha

At the recent Energy show, the payback on PV was estimated at 100 years with the panels expected to last about 25 years.

The following from the IT does not auger well for more attractive payback.

Copyright 2007 The Irish Times
All Rights Reserved
The Irish Times

April 4, 2007 Wednesday

SECTION: FINANCE; Other Stories; Pg. 19

LENGTH: 137 words

HEADLINE: Sales of solar equipment set to hit $90bn by 2010

BODY:


Higher demand for solar energy, triggered by concerns about global warming, will drive a fourfold increase in the annual revenues of the global solar equipment industry from $20 billion (EUR 15 billion) last year to $90 billion in 2010, according to a report published today by Photon Consulting, a German research group.

Profit growth is expected to accelerate even faster, as costs are contained, pushing margins up to nearly 60 per cent.

The interest manifested by many electricity customers in solar cells as a "green" alternative to fossil fuels is also likely to spur a tenfold surge by 2015 in production of high-purity silicon required for the cells.

Demand for the silicon needed for solar cells is likely to increase from 41,000 tonnes last year to 120,000 tonnes in 2010, and 400,000 tonnes in 2015, the report claims.

CJhaughey

I remember reading about a south african PV system that uses a coating on an alloy to generate PV power, it didn't need silicon and was forecast to be a fraction of the cost of silicon tech.