FEB 17

How are we supposed to believe any of this if the magazine that reports it can't even get their basic energy units right?

A kilowatt is a rate, not an amount. "...up to 13kW of heat per hour" is essentially meaningless. 13KW is a rate of producing energy, which is better known as 'power'. 13KW over 10 hours would be 130KW-hours - an amount of energy produced.

"13kW of heat per hour" is like saying 60 miles per hour per hour.

I am excited by the simplicity of this. I loved Rob Cockerham's parabola experiments. Just a few square feet of focused sunlight can be super powerful.

It makes my heart glad to see that the very first comment here is rightly calling the company out on their inexcusable ignorance of the basic fundamentals of energy measurement.

It makes my heart sad, however, that the EcoGeek editors still don't know a kilowatt from a kilowatt hour. How long have you been doing this ? How many posts have I placed here explaining the difference ? How many other people have done the same ?

It's on SolarTron's website and it's repeated by Solar Thermal Magazine and repeated again by EcoGeek. It's not just once either, the whole confusion is repeated throughout their advertising pamphlets and all over the website.

Strangely, although they tell you what an amazing ROI it has, nowhere on the website or in any of the pamphlets do they mention a price. Luckily, they give enough information to calculate a price.

They say: "Data based on 10kW of heat. Average 6.0 hours of sunlight per year, $0.13/kw electricity". Assuming they actually mean "kWh electricity" rather than "kw electricity" and that there are actually 6 hours of sunlight per day rather than per year, then the cost of the thing is $17,082 with a 6 year payback time. However, the difference between heat and electricity is conspicuous. They claim they will be able to produce 4kW of electricity some time in 2011. Based on that rate, it's only $6,832 with that same 6 year pay back. A quick look at a solar panel retail site shows me that I can buy 4kW worth of solar panels with a similar surface area to the SolarTron offering for $6300. So depending on your interpretation of that sentence, it's either 10% more expensive or 150% more expensive. (All prices are in Canadian dollars.)

Lastly, I'd like to address the claims of 262% and 98% greater efficiency than flat-plate and evacuated tube techniques. While I would expect the parabolic dish with it's very small collection focus to lose less heat to convection than the other two techniques with their large surface areas, even 98% seems quite high and 262% greater efficiency could only occur in the middle of winter with very cold temperatures, low sun angle and the panel lying flat. Unfortunately, with no data to back this up, neither of us are any more believable than one another.
One bit of data we do have, however, is that both these other techniques work on cloudy days and even in the rain. Parabolic mirrors require direct sunlight. They produce no power at all with diffuse light. How many days per year do you get 6 hours of direct sunlight ? (I live in London, so about 10.)

For a select few people, this product may be worthwhile. For most, there are better offerings.

And please, please, please learn about energy measurement.

I took the company's more awkward phrasing "13kW of heat per hour" (which I used in my article) as a way of saying 13kWh of heat, similar to "60 miles of travel per hour" being a more awkward way of saying 60 MPH.

We do try to get the units and the understanding right at EcoGeek. I know this keeps coming up because we have made occasional mistakes, but in this case I think we got it right. If there's something I'm missing in here, I appreciate the correction.

I don't disagree that the website is short on some information and sloppy in some of their presentation and marketing hyperbole. But that's a separate issue.

Appropriate siting would be as important for this as it would for many other technologies. The fact that it would be a poor choice for London doesn't necessarily make it bad technology, it just means it would be foolish to mount one in London.

I am not a rocket scientist or any sort of scientist for that matter, but I do try and follow the development and application of solar technology to meet our nations energy needs. That being said several years ago I read about the development of a new type of solar parabolic collector mirror by some students at MIT that is purported to be several orders of magnitude ahead of anything else currently available, including this particular collector. Info on their development can be found at: http://raw-solar.com/news.html
This development led me to wonder why someone has not thought of specifically combining this parabolic collector with a Stirling Heat Engine capable of producing between 4kW to 6kW of electricity for home consumption. While not exactly cheap ( I suspect that current supply vs demand has something to do with this) with increased/massed production of more Stirling Engines the price should drop to well below what is currently being charged for a comparable pv array of similar capacity with a far smaller footprint.

Perhaps someone, with far more knowledge about these technologies than myself, could look into this and see if it is feasible and cost effective. An alternative idea would be to use this parabolic collector with its massive heat output in conjunction with a boiler/steam turbine for the same purpose.

The fundamental thing you must understand in order to talk about watts is that a watt is not an amount of energy. A joule is an amount of energy. A watt is one joule per second.

The difference between "13kW of heat per hour" and "60 miles of travel per hour" is that 60 miles is a distance whereas 13kW is not an amount of energy. It would be the same as saying "13 kilojoules per second of heat per hour" which we can see doesn't make any sense.

Anywhere you see watts, you can always replace them with "joules per second". In fact, you should do this, at least in your head. It will help to understand watts.

I would be happy to see the world do away with the unit watts altogether and just use joules per second instead. Maybe you should use J/s in your articles and specify (W) after it in parentheses, or vice versa. This would certainly make your articles more accessible to people who have not completed High School physics. And being more accessible is certainly a good thing.

The next thing you need to understand is that kWh is kilowatts multiplied by hours, not kilowatts per hour. That is, 20kWh is 20,000 joules per second multiplied by 3600 seconds. (Which is the number of seconds in an hour.) Since there is a division in this equation (J/s) and there are seconds on the top and seconds on the bottom, they cancel each other out and we are just left with joules as the unit the answer is measured in. Therefore, kWh is an amount of energy. This is especially confusing for people because it has "hours" in its very name, and yet it is not a rate per hour. It is simply a measure of joules. As before, you can always replace Wh (watt-hours) with "x 3600 joules" and kWh with "x 3600 kilojoules".


The thing about the site EcoGeek, is that you attract geeks. Geeks are the sort of people who care about the details of things.

We know that recycling isn't always good, because sometimes it uses more energy and pushes more toxins into the environment than throwing something out and making a new one. For a long time a solar panel could not generate enough energy in its entire lifetime to create another solar panel. Before we recycle or before we buy a solar panel, we need to know that it's actually helping the environment.

If you show us something new and shiny, we're going to take it to pieces to make sure it's shiny all the way through and not just on the outside.

OMG, OK, so someone made a typo somewhere... and it's hard to appreciate or dis the technology appropriately if we don't know exactly where it is in line based on regular solar panels (which I also don't have and won't be able to afford for some time). Could we assume that it will achieve some type of reasonable efficiency and competitiveness with other renewable/low carbon/alternative energy options and look at the concept?

because of the high level of heat achievable, could that concept be used for cooling in sunny regions by making a giant refrigerator out of a home using some coolant?

Waaaaay back (several decades ago), I once read a small article on some African area using a solar collector to beam concentrated heat on a flat black 'ball' target which was filled with a fluid. Said fluid was heated to steam and ran a steam turbine for local power.

Why do we not see that kind of 'single home use' technology now, so many decades later?

Everybody seems to be attacking the author for a small mistake with stating of units, but not commenting on the idea. (I sometimes have an over-60 mental block with joules and watts, and are they per second or per hour....: )
If this dish performs at 13kW (in strong sunshine) that is colossal, and few houses or buildings using even this micro sized dish would know what to do with such amounts of heat, especially in summer. However, I have done some work on Solar Charging for boreholes, and with [theoretically] thousands of tons of clay below, it is possible to dump such amonts of heat into an almost infinite sink, and most of it comes back in the winter months using efficient heat pumps. I am putting 3,000 kWhr of summer heat into my deep boreholes, and getting all of it back in the winter.
My garden would not be big enough for a 4.5 metre dish, but good luck to those who do!

Units are critical in understanding the value of a product Just as importantly, they're critical to people/consumers understanding the underlying concepts involved.

We're not attacking the author for one typo. If there's any "attack" going on at all, it's for a stunning lack of understanding of a fundamental and basic concept: the difference between power and energy. This crap happens over and over on Ecogeek, and is so, so irritating to see repeated.

To be fair to Ecogeek, the actual company that sells this thing listed the same bogus units on their own website, which is way worse than some blog copying and pasting their mistake.

Thank you SO much to Qweeg and Dave for their posts on the units.

Such basic "units of measure" errors by editors of supposedly energy-related publications as confusing power with energy (see Dave's correction above) REALLY need to be fixed for this publication to gain any level of credibility. The ed. needs to understand it in order to weed out nonsense press releases. The above technology is probably not worth the time to investigate if the company / "inventor" is so unaware of physics as to allow a press release to contain such errors. Editors who insert the errors themselves do a huge dis-service to legitimate companies. Editors who repeat such errors waste our time.

I am also surprised at ecogeek for not going "a little deeper" and checking the validity of this sales pitch by SolarTron. To even suggest that such a product can be used in the residential homes, is a false advertising, according to the information from SolarTron, this 15 feet oval dish is only good for temperatures in excess of 150ºF providing 13KWH system way more than what might be needed in a normal home. Now consider the price of such a system, one oval dish has a resale tag of $20,000 this is just the dish, in order to mount it for a home you will have to install it on concrete pad outside with footing below frost line, if you want stability. If this is not enough, you will need to dig a trench to the house, again below frost line, entering the house through the foundation wall. By the time I add all of this extra work, the customer will be paying about $28,000, the company shows that such a dish when you use 280gallons per day of hot water at 160ºF and that is a lot of hot water production for a typical home with 4 or 5 people in it, will save you $2600 per year. In my book this is a 10.7years to pay back this system and a lot of out of pocket money to come up with, even if you get some back from the Federal Gov.
EcoGeek should be careful when they provide such information, it should be checked first and printed later. Dan

Glad to see someone beat me to the Unit comment - its not just EcoGeek which seems to have technically illiterate authors, GigaOm made a similar error recently on a "Smart" grid device. and OurWorld also commenting on the plastic to oil.

The reason its important is that often it makes a 10x difference, for example if something says 13kw per day which happened on one article recently - it can mean anywhere from 13kwh to 13kwh * 6 hours of sunshine to 13kwh * 24 hrs. This makes a huge difference if you are trying to work out payback.

I don't know how EcoGeek rights its articles, but it looks like its just parroting press releases without understanding them - I would have hoped that journalists at something with "Geek" in the title would know enough to question an obviously meaningless press-release before repeating the mistake.

This is a great idea and I wonder how it would hold up in colder climates with only a small window for sun i.e. Alaska.
Futher more, would it be possible to put a coating on old dishes and retro fit a receiver to do the same as this unit? Satilite and heating sold as one package! hot dog!

I installed one of these dishes at my home, and it is truly amazing. Right off the top, I get 30-40% more solar gain than any stationary unit, due to it's two axis tracking. My previous flat plates, I replaced, did not start producing hot water until almost 9:30am, and now on the same day, it starts at 7:00am. Same for sunset, I get several hours more each day. Fix units are a thing of the past, as they by design loose 30-40% of potential sun by being fixed. I also have very little heat lost in the winter. Fix units have large radiating surfaces to loose heat on cold days, my collector area is only about 1 square foot, not 300 square feet. Also, I can get temps to 200F degrees on a freezing winter day, try that with any flat plate. Also, flat or evacuated plates get very little solar gain on cloudy days. It is true a concentrator needs a better direct sun, but I have never seen any other thermal collector produce much heat on a cloudy day. Also, this unit can never overheat, it simply tips away from the sun if your max temps are reached. If there was one negative it would be the unit is made up of moving parts that can require servicing at times. In the past year, I have performed two 3 hour repairs. In New England we have many cloudy days, so I wanted a unit that would grab as much sun as possible when the sun was shining. I got exactly that.