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April 04, 2007


Thomas Foreman

I'm very happy to see
Solar Solutions.

Susan K

Is one $1000 cube is enough to power an average US home? Thats major step to affordable! That would outcompete a $25000 solar roof.

How can we get these here in the US?


One is not enough to power an average US home. I subscribe to the Yahoo group that Green and Gold's founder maintains. Subscribe to it if you want to hear tons of nay-sayers, many "how much is it and when can I get one" types, and an increasingly pissed off Aussie owner who feels he has to answer all the nay-sayers and gets himself quite worked up in the process.

I myself am quite keen on his product and definitely want to give it a try when my wife and I buy a single family house in the coming years however the email digest is painful and made me stop reading it long ago. I'll check Green and Gold's WWW when I'm ready to make the plunge.

greg woulf

The average household in America consumes 10,656 kilowatt-hours (kWh) per year, according to the Department of Energy.

Taken from 2006 numbers, which I think still hold close. That makes it look like it'd take 15, or $15,000, plus you'd have to live in an area that allows you to sell to the grid.

Where I live I pay around $1,000/yr, but I know most pay more. I know I don't use the whole 10,000 kwh, but even so it'd take me 15 years without interest, 25 with interest.


This is just the first of the concentrating solar solutions to hit the market.

At $ 2.50 (US) per watt its very cheap but I expect them to get much cheaper as production is automated.

Reliability is the only question.

Harvey D.


In areas with a daily avg. of 6 hours of sunshine, this unit would produce only 273 watts avg for 6 hours a day. The initial cost would be $3.66 US per installed watt.

Storage units + i/p and o/p control systems would cost at least another #3.66 per installed watt for a total of about $7.32 per installed watt.

To satisfy the avg US home with 29.2 KWh/day you would need at least 18 cubes = $18 000 + another $18 000 for i/p and o/p + storage devices for a minimum of $36K.

Assuming that 10656 KWh cost an avg of about $1000, it would take about 36 years to recouperate your initial investment.



I don't know where you get your numbers.

For example:

"To satisfy the avg US home with 29.2 KWh/day you would need at least 18 cubes = $18 000 + another $18 000 for i/p and o/p + storage devices for a minimum of $36K."

US homes do not consume anything close to 29.2 Wh/day...

Why are you pulling numbers out of thin air ? Do you have a grudge with this company ?


greg woulf

What are i/p and o/p that costs another $18,000?

I've installed home systems and there's inverters or maybe transformers, but they don't cost a lot.

Batteries to store the energy might cost some, but I think a lot of places can sell to the grid. It's something I think will come for most areas eventually.

29.2 is right though, or at least according to the U.S govt it's right. I got the 10,656 number per average household directly from a DoE site from 2006.

It's a long term proposition, but from what I've read they retain their value in a home.

Harvey D.


Most of the 'associated' cost would be for enough energy storage devices and high power converters to handle peak and overnight loads + extended periods without sunshine (cloudy + rainy days etc).

A bidirectional energy sharing arrangement with the power grid could be a cheaper way to manage production/consumption mismatches.
However, the system still have to be powerful enough to provide the avg. yearly load i.e. 10650 KWh/year, i.e. 18 cubes. (20 cubes would be more realistic due to conversion and storage lost)

If one is satisfied with enough sun power for a small TV + a low power fan + phones + a few florescent lights, that is another story.



I'm not great at math and kind of new to this technology but apparently the average U.S. household uses 866 KWh/month. Divide that by 30 and it is rougly 29 KWh/day, right?

I think the numbers might be right but I'm not an expert. If the cube produces only 600KWh/year then you would need about 17-18 of these cubes to produce the 866KWh/month over the course of the year.

Does this sound correct? Being that I'm new to this I'm trying to wrap my head around the numbers.

Charles S

Like the current hybrids and EVs, the worse enemy toward progress is to nickel-and-dime it to death. Why should we always view alternative, residential power generation as all or nothing scenario?

First of all, while living entirely OFF-GRID is a goal (and some may say its money well spent), it is not really necessary in an urban environment. Besides not being cost competitive (for now), the rest of the city that needs centralize power anyways, and we might as well take advantage of its benefits. That being the case, it is not necessary to size a system to feed 100% of the energy, but matching the baseline consumption is a good start.

Second, wastes from big energy hogs such as heating and cooling, water-heater, etc. can be reduced with other methods. Once consumption is down, the sizing of solar panels can be reduced, and thus further bringing down the costs and payback.

Third, with grid-tie devices and some kind of net-metering regulation, a battery option is nice, but not a necessity. For the budget-minded, I'd size a battery enough for a fridge and a little extra, just in case, for the few times a year when power goes out.

Fourth, yes, it'd definitely be nice to be generating a surplus, but I wonder if taxes from profits would be a big headache anyways. I'd rather generate enough for my own use, and enjoy the intangible benefits such as being shielded from price spikes or outages.

I can go on, but all these points illustrate that conservation+solar is doable, and a medium solution can be cost-effective and more advantageous than all-or-nothing model.

Charles S

"...then you would need about 17-18 of these cubes to produce the 866KWh/month over the course of the year."

That may be true, as an "average," but when it comes down to the actual application, it's going to be a case by case basis.

The bad news, the rating of the SunCube is also just an average number. Where you live affects how much you will actually get from the device, and of course, how many sunny days you get for the year. If one is really shooting for EXACTLY 866kwh/month or more, then you may need to get a few more just in case...

For anyone who is serious about this, I'd encourage working toward conservation first, before getting a sticker shock from pricing a giant system, which would end up feeding wasteful appliances anyways.


On Green and Gold's website:
if you look carefully you can see that one of their SunCubes looks like it puts out 0.3 kW, or 333 watts. That's not a big output. Here's an average scenario for a typical US household (note all these #s may vary considerably):
Daily Electricity Usage: 30 KwH/day
Avg. hrs. of sunlight: 6 hours/day
SunCube efficiency: 90%
% of total electricity usage supplied by SunCubes: 100%
then the # of SunCubes you would need would be:
0.3 kW x 0.9 x 6 hrs/day = 1.62 KwH/day (total output power of 1 SunCube)
30 / 1.62 = 18.5 SunCubes
So to be on the safe side, you could purchase 20 SunCubes for $20K + installation, and generate enough electricity to cover yourself (if it gets sold back to the utility grid).

Ronald Brak

These sun cubes are pretty neat. With the government subsidy there are sunny places in Australia where the electricity they save is enough to meet the payments on a loan used to purchase them the system. This means they should be pretty popular. I think I'll talk my sister into getting some because where she lives is like an oven and her air-conditioning bills are enormous.

Jim fro The Energy Blog

The units come with the inverter installed providing 240V AC output. There are no mechanical parts required for installation, other than some bolts or lag screws. Electrical installation will require some parts. I beleive it says somewhere in the discusion group that an electrician and a helper can install all the units for a household in a couple of days.

It makes most sense to install these taking advantage of net metering regulations. These are in effect in about half of the US. Net metering means that you get credit for the excess electricity produced during the day and you use the credit to purchase electricity at night (hopefully at an off peak rate). The reasoning is that the utility gets relief during the period of peak demand.

The capacity of the units have to be adjusted for the solar radiation in the area where the unit is installed. On their website G&G provides a methodology for this along with some very good maps to determine the solar radiation.


That website is a shocker! Never let engineers do marketing! As an Aussie I'd love to see them succeed, but they definitely need to improve their image and make information on the site easier to find.


Regarding economics I downloaded their spread sheet calculator and looked up the NASA solar energy for my farm (Midwest US) and determined the system will pay for it's self in 139 years. As neat as sun power seems this is obviously not a logical investment.

All the Australian example sites shown on their calc sheet indicated about 2 times the solar energy we have here. So the 600kWh/year may only be about 300kWh/year here in the midwest. This would make the bad investment even worse.

I have looked at building my own solar to electric system from basic components. I calculated about a 20 year payback doing it this way. Wind has a much better payback being about 7 years for my location. Economically it's better to let the power company install the wind machines and just buy the power.

If you want to install a system to off set some utility costs just for fun then great. But don't do it to save money because it won't. JohnBo

Ronald Brak

JohnBo, I don't really see how we could have twice the sunshine here in Australia as you do in the U.S. Midwest unless the weather there is much worse than I've been led to believe. Perhaps your figures are for a non-tracking PV system?

The solar cube is rated to produce 786 kilowatt-hours a year in my town. Using U.S. figures I pay about 11.25 cents per kilowatt-hour in the day. That comes to $88.42 a year so the solar cube would pay for itself in 11 years and four months without including any government subsidies. If it was installed in Alice Springs in central Australia where it would produce about 913 kilowatt-hours a year it would pay for itself in under ten years.


Oh dear!

i find myself having to cuth through the BS and do the real math.

And yes the site is a mess. But (and a big but) all the real information is there, as opposed to many "slicker web sites" that don't.

Solar 101 (as I see it).

For grid tied, it's all about yearly solar harvest. Max watts is bulls__t. Invented but flat panel makers to improve their numbers.

From the website. The Suncube collects 35.4% of the DAILY DIRECT BEAM RADIATION.

Here is the link (NASA) used to caluculate the abouve figure.


You need to log in to use it.

For those who what an idea without doing the clacs.

If you get 4kWh per day DB radiation the sun cub produces

0.354 x 365.25 x 4 = 504 kWh per year.

for 5kWh per day = 630 kWh per year.

for 6kWh per day = 750kWh per year.

Divide your real yearly use by your DB calculated number an you have the number of cubes to totally displace your consumption.

Most of us live between 4 and 6 kWh per day DB. Those that get more are lucky, those less......don't buy the system.

so for 10 650kWh per year use you need

@ 6kWh DB rad - 14 cubes
@ 5kWh DB rad - 17 cubes
@ 4kWh DB rad - 21 cubes

I have seen figures of USD1000 per cube (inverter included, but not instalation).

Hope this helps!




You need a lot better efficiency and heating/cooling

to make concentrating PV pay its own way.

greg woulf

I think you're blowing the numbers up Harvey.

If you sell to the grid it's somewhere between 15-18 cubes average. If they come with an inverter then that's a 25'ish year payback.

That's not a positive investment, but it's not a negative one either. If I can break even and do something that will lessen the damage I do with no convenience loss I say it's still a good investment.

If you add in storage I'll grant you that it's a whole new calculation. I don't like current storage anyway because of the short life.

Paul Dietz

JohnBo, I don't really see how we could have twice the sunshine here in Australia as you do in the U.S.

Much of the sunlight in the US midwest is diffused through clouds, which a concentrating PV system like this mostly cannot collect. A flat plate or non-imaging concentrating system could, though.

Harvey D.


I agree with you that to turn these 18 to 20 cubes into a somewhat acceptable investment one would have to:

1) be in a very sunny dry place with 6+ hours/day of avg. sunshine.

2) sell sunshine time (surplus) power to the grid at high price.

3) re-purchase (the same power) from the grid (at lower cost) during low or no sun shine hours.

4) have minimum or no storage capabilities.

5) reduce the number of cubes to your day time consumption level (whatever it is) and rely on the grid for all the rest.

Bill Hannahan

Look at it from the utilities point of view. Let’s say you have a power plant that produces electricity for 3 cents/kWh which you sell for 9 cents/kWh. The 6 cents/kWh covers all your expenses and profit.

Net metering laws force you to buy customer generated electricity at 9 cents/kWh, so you loose the income. If everybody installs enough wind and solar capacity to net zero you have no income.

Net metering laws force you to provide very expensive battery service for free to people who can afford to dabble in wind and solar, and you make this up by raising rates on the people who cannot.

The electricity you buy directly from the utility for your home is only 1/3 of all the electricity that supports your life, 13% of all the energy that supports your life. If you install enough wind and solar to go off the grid you still have to pay for the remaining 86%, which comes mostly from fossil fuel.

Ronald Brak

With the Australian government subsidy and a 25 year lifespan, in my town the solarcube will be a good investment if your discount rate is about 7.5%. That means it's a better investment than putting your money into a term deposit.

In a very sunny location such as Alice Springs it will be a good investment if your discount rate is about 9.5% which is approaching the average return on the stock market while being a lot more reliable.

Since Australians are fond of home improvments and many have access to capital at around 7.5% interest, I expect solarcubes and similar systems to become quite popular here. I also expect their price will be even lower in the future.

Charles S

"Much of the sunlight in the US midwest is diffused through clouds, which a concentrating PV system like this mostly cannot collect."

I believe the owner of the SunCube design says that his device will do the opposite.

Charles S

"I believe the owner of the SunCube design says that his device will do the opposite."

Wait. Let me rephrase that. My opposition to the comment "concentrating PV system like this mostly cannot collect [under clody days]" is NOT saying that CPV will work WELL under cloud days, but that I oppose that CPV "cannot" collect under cloudy days.

Greg Watson himself will have to defend the comment, as he mentioned, quote "Even in VERY cloudy locations, the SunCube can still deliver annual kWhs at 50% the cost of annual flattie kWhs." Flatties is his term for the flat panels.


From the SunCube website:

The internal microprocessor can also command an increasing spiral sky scan to find and lock onto the sun or brightest sky spot if the sun is obscured by clouds.
Jim from The Energy Blog

Greg Watson (CEO of G&G)sent me a note saying that: "the latest SunCube Mark 5 test data shows 711 kWh per year under Adelaide 5.5 kWh / m2 / day direct beam solar insolation. That relates to a SHE (Solar Harvest Efficiency) of 35.4%. SHE is defined as the delivered energy from the horizon to horizon annual direct beam energy availability at the location and has nothing to do with the peak watts that the flatties use. Here is the calc we use:

Annual kWhs = 5.5 kWh / m2 / day x 35.4% SHE x 365.25 days per year = 711 kWhs per year. So much easier, accurate and simpler than the peak watt stuff."


Jim et al,

Did any actually read my comments?

I enjoy reading and sometimes (not often) participating but it can be highly frustrated to see further comments that seem to totaly disregard that which is written above.

To Bill Hannahan

What are your comments on avoided cost? The NSW state gov (australia) feels that there is a real value to "dabble in wind and solar".


Avoided cost benefits capture and return to the renewable generator purchaser such as the DEUS system:
· Retailer avoided cost of $33 per MWh generated
· Distributor avoided cost of $225 per kW installed capacity per year
· Generator avoided cost of $11.50 per tonne of CO2
· Value of $296 per year or $0.197 per kWh (1 kW system generating 1,500 kWh per year)

Back into my shell.



I think I know why now!

My grammar is awful.

Apologies to all


greg woulf

The midwest is a good place to grow mushrooms. Solar value shouldn't be judged there. You need to look at something like Algae growth for biodiesel.

For the rest of the non-vampire world it's a possibility. If each cube comes with an inverter there's just the hook up cost to the utility and these things should pay for themselves in 15-25 years.

Harvey D.


All those 'avoided cost' would only apply on a 'stand alone' system NOT connected to the grid.

A 'stand alone' system would require high capacity (expensive) storage or a combination standby generator + smaller storage units.

The total initial cost will be close to $36k for the average American home or for 10650 KWh/year. Even at 5% interest, pay back time would be much longer than the system expected life duration. It may be justified for far isolated places only.

Sorry, up-to-date nuclear plants + undergroung cables (or existing infrastructures) is much cheaper and more reliable in most places.

PS: Our new place is supplied with underground hydro-elctricity + NG (for the fireplace and BBQ)+ fiber cable for telephone + HDTV + High speed Internet. Nothing above ground except the fancy street lights.

greg woulf

I still don't agree with the numbers, if the units come with an inverter especially.

If you're connected to the grid then I think it's a straight 18k.

Paul Dietz

I believe the owner of the SunCube design says that his device will do the opposite.

If so, he is not being physically accurate. The SunCube uses rather high concentration, and such systems necessarily have a narrow solid angle of acceptance (if not, you can violate the 2nd law of thermodynamics.)


[The NSW state gov (australia) feels that there is a real value to "dabble in wind and solar”.]

Mike, my first sentence was, “Look at it from the utilities point of view”.

Perhaps I should have said,

“Look at it from the point of view of a middle class citizen who is too poor to dabble in wind and solar, yet not poor enough to receive utility charity payments from the government (read taxpayer)”.

Net metering laws force utilities to raise the kWh rate on these people to cover the cost of providing free battery service to owners of intermittent energy systems.

I believe net metering laws are unethical and create economic distortions that lead to inefficient non optimum decisions.

I feel the same way about allowing utilities to vent mercury, sulfur, cadmium, NOx, etc. into the atmosphere free of charge.

We should work to eliminate these distortions, not add more, and let the market pick the best solutions.

R&D for non fossil energy sources should be increased 100 fold, but not on the backs of the lower middle class.

Jim, I cannot find the dimensions of the collector but the shipping dimensions are

0.9m x 0.9m = 0.81 m2

The photos show wide structural bands around the perimeter and across the collecting surface, so I would guess the effective lens area at about .7m2. Assuming a reasonable number for inverter efficiency, say 0.94, I don’t see how you can get 711 kWh/ yr.


Oops, shipping dimensions are

.95m x .95m =.9025m2

In my mind I was guessing actual dimensions might be .9m after unpacking.

Kit P.

Energy Northwest (http://www.energy-northwest.com/ ) provides some real time data for wind and solar. Their 30KW PV system produced 64 kwh today.

Greg Watson

Hi Guys,

The reason we don't quote peak watts is that it really means nothing. The only figure that is important is annual kWh output.

We use a new measure called SHE (Solar Harvest Efficiency). SHE is the real output percent that you achieve from the direct beam horizon to horizon annual solar availability. The SunCube has a measured SHE of 35.4%. So to figure annual SunCube kWhs you calc:

Annual kWhs = direct beam kWhs / m2 / day * SHE * 365.25. BTW the SunCube solar collection area is 1 m2.

So under Adelaide skies with 5.5 kWh / m2 / day we then get:

5.5 x 0.354 x 365.25 = 711 kWhs per year. See no peak watt data needed. Just real world data that results in real world output.

Additionally the SunCube produces about 2,400 Wh annually per peak W versus a flat panel at about 1,500 Wh annually per peak W (under Adelaide skies). We achieve this by 2 axis tracking and capturing both direct beam and diffuse solar energy. From our research this is a world first.

Here we graph the SunCube annual kWh output across the various direct beam solar availabilities for Australia:


All the best
Greg Watson, CEO
Green and Gold Energy
Adelaide, South Australia
+61 408 843 089, Skype "gowatson"
Online SunCube discussion group


Kit P

Interesting site. The White Bluffs solar facility produced an average 2.24 kW over 5 years for an average capacity factor of 7.6%.

The DC capacity is 38.7 kW and the AC capacity is 29.5 kW implying an inverter efficiency of 76% which seems low.

Cost $250,000

Kit P.

No, the only figure that is important is the amount of electricity that is produced when you need it.

Kit P.

Bill, I think White Bluffs was built as a demonstration facility. Notice that the wind farm is expanding. If you check the annual report, it looks very economical compared to natural gas. The combination of hydroelectric and wind in the PNW makes a very good renewable energy combination.

Greg Watson

Hi Bill,

Sounds like you are off grid and if so I agree with you. At peak sun (1,000 W / m2) the SunCube can generate in excess of 300 Wdc. ~25 Vdc @ ~ 12 Adc.



Excellent performance Greg, you should do well with this product.

I am curious about two things.

What would you expect average inverter efficiency to be over a year of average weather.

How do you pack a 1 m2 collector in a 0.9 m2 box?

Greg Watson

Hi Bill,

The measurements are of the Mark 4 SunCube and not the latest Mark 5. Details like this are covered on the SunCube discussion group.

The Mark 5 is 1020 x 1020 x 250 mm. The solar collection area is as advised 1 m2. The photo on the web site is of a smaller size lens set that we used to test output at low solar energy levels. The production Mark 5 SunCube has lenses that cover the entire 1 m2 area.

To understand inverter efficiency you need to understand the SunCube has an almost constant output so unlike flatties with their peaky output, the daily SunCube inverter efficiency is very high ~= 95%.


So the inverter is working at optimal load almost all of the time and not just for a few noon like hours as flat panels.

The SunCube has almost no comparables with flatties. It is next generation.


Gil Walker

EPACT 2005 requires all utility companies to purchase energy that you generate or install a meter that run backwards. Check with you local utility company, storage devices like battiers are not needed. This system comes an dc/ac inverter.

The cost between $2.8 watt and $3.60 watt is very resonable, Florida offers a rebate of $4.00 per watt. When this system is offered in the US how will the existing rebate programs change?

Gil Walker

Visit the following web site for a list of federal, state, and utiltiy solar tax credits and rebates in your area: http://www.dsireusa.org/

Some areas offer enough rebates that would cover the purchase and installation cost of this system. FREE ENERGY....


This is all bullshit.
The Suncube pictured is a dummy.
There is not one single working Suncube or Sunball in existence.
The factories do not exist.
The output claims are fantasy.
To find out more go to Google Groups Sungrid.


The daily average consumption in north america is registered at 16,7, but most of us in city must use around 40 if not more..
from my research it would cost about 480,000 CAD to built a 60KW installation that would produce an average of 240Kw/h per day at 4.0 radiation level.
So my opinion is that this technology is viable only in larger scale project were you sell directly at the grid.

Scott Cunningham

I have retrofitted my house with energy efficient devices in Perth & just become more concious of my power consumption.
If i buy two cubes and sell to the grid I will be making money.
The US obviously use significently to much power. 29kw/day thats ten times more than me damn you guys need to get it together.

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