Solar Energy

[Jammrock]

My wife and I hope to get some land and build our dream home in 5-7 years (roughly). We have been looking at "green energy" options, and I must say that solar power has really come a long way.

It's too bad adding solar to your house is FREAKING EXPENSIVE!!! A 5000W system from Sun Power runs almost $50k USD. Wind simply is not an option here, there is not enough constant wind to justify the cost, but we get plenty of sun.

Does anyone have experience with lower cost, but still decent power output, systems? I've read a bit about solar shingles, any idea if they are cheaper? I'm sure all of this will change a lot in 5-7 years, but it has peaked my interest.

[Tjalfe]

the 50K, is that using a battery bank, or using the Grid as the storage medium?

[Marshmallowman]

Good quality solar cells pretty much average out at around $10 a watt, you could get cheaper but they will probably degrade a lot more than good ones.

mono crystaline > multi/poly crystaline> amorphous
(thats quality and price, but I would get at least mono crystaline for house, 25 year warrantee and up to 40 year usable lifetime, and the price difference is not that much)

You set it up so you can expand it as time goes by, and solar PV's get cheaper.

Eg start with 1 KW worth of cells and a flexible inverter rated to the power you want to get to.

That what I am looking to do to my home, luckily here we have a government subsidy of $8 a watt up to $8000.

[Brian Ellis]

Hold fire until the last moment: prices will come down and efficiency will increase slightly.

The only reason I haven't done the same is that it is a bureaucratic nightmare here. I applied and the electricity supplier approved, but I gave up after two years of battling with three different ministries and horror stories of others not getting back a penny of their investment many months after the installation was complete.

IMO, avoid battery backup: sell your excess. I have a friend who thought he could be 100% dependent on his own solar electricity (no grid connection) but he quickly found he had to have a diesel unit as well.

[Dr Mordrid]

You can split between selling back and providing a battery backup; just have a smart charger that switches to sell-back when they're fully charged.

In the next year or two several advances in solar panels will be coming to market, two of which look to be priced at <$5/KW.

[Brian Ellis]

And, of course, solar hot water. There are two types. The most efficient is the direct but is suitable only for areas where the coldest night-time temps is more than about -3°C and there are no frosts lasting >12 h (this is the case here and 96% of the habitations, offices and factories etc. on the island below 800 m altitude are thus equipped). The cost of 2m², which is adequate for most households, is typically ~€500 and it pays off in <2½ years. We can shower comfortably ~345 days/year without supplementary heating. The panel is fitted with direct connections to the hot water tank, at a slightly lower level, and it works entirely by convection.

If hard or prolonged frosts are possible, then you have to go to the indirect method which is much more expensive and may take 8-10 years to pay off. Here, you have a large heat exchanger in the hot water tank (hence the major cost) and you need 50% more panel size, as the losses are higher and the heat transfer is poorer due to the fact that the primary panel-exchanger circuit is filled with antifreeze solution and not just water. This method is OK up to ~60° latitude (you may need more panel area and focussed panels at higher latitudes). I know people in the UK with such systems.

Of course, you must also have another water heating method to cater for when the sun doesn't shine for three days on the trot.

[Wulfman]

just thinking - do you plan to create a "passive" house? might safe you more in the long run instead of just producing electricity...

otherwise, I'm with brian - I'd consider adding heating elements as well es electric power (are they actually energy neutral over their lifetime by now or was that a hoax to start with?). and I'd look into installing a heat pump.

mfg
wulfman

[Brian Ellis]

Not a hoax, simply disinformation (aka downright lies) propagated by vested interests.

[Evildead666]

Why not look at some geothermal solutions also.
They pump the air input of the house heating underground to heat it up a bit, and thus you use less fuel getting it to your required temperature....

[Wulfman]

Not a hoax, simply disinformation (aka downright lies) propagated by vested interests.

thanks. took the time to look around: http://pubs.acs.org/cgi-bin/abstract...es071763q.html

mfg
wulfman

[Brian Ellis]

At least 89% of air emissions associated with electricity generation could be prevented if electricity from photovoltaics displaces electricity from the grid.

And if the grid were fed from PVs, then the prevented emissions would be 99.9879% for the first generation!!!!!

[Jammrock]

the 50K, is that using a battery bank, or using the Grid as the storage medium?

Grid.

I've seen some stories on newer tech that promises as little as $1 per W (I would expect $3-$5 per watt installed). If that comes out by the time I build I would certainly plop down for at least a 10kW system (roof size permitting). As it stands it's just to expensive. A professor at Berkley (the most liberal establishment in North America) came out and said PV solar power simply was not financially viable yet, which I'm beginning to agree with.

Hopefully with eco-friendly/green being such a big thing, and appearing not to be a fad, some serious research will go into building me a better solar panel.

[Marshmallowman]

They don't do it much in home installation, but on industrial arrays they use a concentrator setups. They use a bunch of mirrors to feed a smaller array of solar cells, that saves them a lot of $$, even with the solar tracking that is required

PV olar cell efficiency actually goes up in concentrator setups, if you can keep the cells cool enough.

I think the most efficieent may still be solar furnaces, especially with the new "blacker than black surfaces" that have been developed recently....

[Claymonkey]

I've only dabbled with solar research, but I'll be interested to see what happens in the next 5-7 years myself.

[Brian Ellis]

I did an enormous spreadsheet to do all my calculations. Theoretically, with the government subsidies for the capital investment and the payback for produced electricity, I calculated amortisation, with interest on investment calculated at 3½%, in about 8½ years, which would have been acceptable. Without the subsidies or payback, it would have taken 35-40 years, which is longer than the life of the panels. What should also be considered is the lifetime of the inverters, which is typically ~10-12 years, on an average.

As it happens, the price of fuel has altered the calculations. At the time, I was paying about CYP0.06/kWh and I estimated that the this would rise well above the inflation rate, so I added 5%/year. The payback rate was CYP0.12, so I had a clear gross profit of CYP0.06/kWh to start with and that went a long way in the amortisation. However, 4 years later, I had not anticipated oil reaching $100/bbl, and my latest electricity bill charged the kWh at €0.153 (CYP 0.09), instead of CYP0.075 for this year, according to my calculations. This would obviously have lengthened the amortisation period very considerably. (Electricity here is all HFO-fuelled.)

I do not regret having thrown in the towel.