Researchers at Boston College and the Massachusetts Institute of Technology (MIT) have produced a single technology that accomplishes what is currently only accomplished with two separate units: thermoelectric and photovoltaic solar electricity generation.

As we have pointed out previously in the Solar Choice blog, solar hot water systems are one of the most effective ways to reduce home energy costs; water heating accounts for 30 to 40% of the average household’s energy bills by using the sun to pre-heat water for showers, baths, and basins. Solar hot water systems absorb heat from the sun and concentrate, heating the water inside. Thermoelectric technologies, a broader category that encompasses solarthermal technologies, can utilise heat from the sun, fires or elsewhere to generate electricity. Solarthermal generation can be similar in principle to concentrating solarthermal electricity generation, except that concentrating solar thermal generation typically requires large swathes of land for mirrors and giant towers to spin turbines to generate power (much as in a conventional coal generation plant). Solarthermal of the type and scale developed under the MIT/BC project would not generate enough power to do so.

Solarthermal technologies have not been deployed as widely as photovoltaic technologies have. Photovoltaics solar panels convert sunlight directly into electricity, which can then be used by appliances in a home or fed into the electricity grid.

Solarthermal and photovoltaic technologies have always been manufactured in separate units. The combination of these methods of generation in the technological development at Boston College and MIT has the potential revolutionise the way that the power of the sun is utilised in homes and elsewhere. The team of researchers used nanotechnology (nanostructuring) to combine into one flat-bodied panel materials that have thermoelectric properties with photovoltaic materials that selectively absorb certain parts of the spectrum of light. The technology promises efficiencies up to 8 times higher than the previous record for solarthermal, and would not require large arrays of high-precision tracking devices to aim mirrors and concentrate sunlight, as is the case with many solarthermal technologies that are currently deployed, such as the solar towers in Spain and parts of the US.

There are a number of potential benefits associated with the use of solar photovoltaic/solarthermal technology: a panel would not require as much material to manufacture, and would not be affected so significantly by orientation with regard to the sun. It could also be integrated with a solar hot water system: water inside the panel would be heated by incoming light, whilst the exterior materials absorb the sunlight and convert it to electricity. This dual-action effect greatly increases the overall sunlight-to-useable energy efficiency of the unit, promising payback periods of up to one third shorter than those of conventional solarthermal panels, according to Zhifeng Ren, a co-author of the paper on the technology.

The hybrid technology would not be a replacement for solar hot water or solar photovoltaics, but instead would be “another way” of utilising the massive amount of solar power with which the earth is inundated on a daily basis, according to says Gang Chen, MIT’s Carl Richard Soderberg Professor in Power Engineering and director of the Pappalardo Micro and Nano Engineering Laboratories. œWith the use of other or new thermoelectric materials that can operate at a higher temperature, the efficiency may be improved further to be competitive with that for state-of-the-art amorphous silicon solar cells. This can potentially provide a different approach to realizing the $1-per-watt goal for solar-electricity conversion, says Li Shi, associate professor of mechanical engineering at the University of Texas, Austin.

Written by James Martin

Solar Choice Analyst

© 2010 Solar Choice Pty Ltd

Sources and Links:

Ecoseed.org, “MIT and Boston College researchers develop hybrid solarthermal technology”

MITnews, “Solar power, with a side of hot running water”

Boston College office of news and public affairs, “BC researchers report on solar-thermal flat panels that generate electric power” (top image also from this website)

Previous related Solar Choice blog entries: Solar Hot Water: an introduction : What type of solar panel is best for you? : What is grid parity and what does it mean for solar power? : Tilt angle and orientation for solar panels in Australia

Jarrah Harburn wrote this excellent piece a while back summarising the benefits of solar hot water systems, and the different types of systems that are available in the market. We here at Solar Choice have received a number of inquiries about whether it is possible to receive rebates for solar hot water systems even if you already have a solar power (photovoltaics or PV) system installed on your home, as well as a number of questions about what types of incentives are available for such systems. This entry answers these questions and provides and overview of the application process for solar hot water rebates.

Solar Hot Water and Solar Photovoltaics – What’s the difference?

It’s probably a good idea to cover this topic briefly before moving forward just in case you are not clear on this point. A solar hot water system usually sits on your roof using the sun’s rays to heat up and then store the water that eventually comes out of your shower or tap. The work done by these systems is usually supplemented with conventional gas or electric heating when your water temperature is below what you desire. Water heated with a solar hot water system cannot be fed into any pipelines for other people to use–the water heated is utilised solely by you.

A solar power (photovoltaic) system, on the other hand, produces electricity which is either fed into the electricity grid and shared for a price under a feed-in tariff scheme (making or saving you money), used directly by appliances in your home, or stored in batteries if your system is not connected to an electrical grid. Power from your solar power system might be used indirectly to heat your water, but generally solar hot water systems do this job much more effectively.

What kind of incentives are available for Solar Hot Water?

We have written extensively about the types of incentive schemes available for PV systems throughout Australia (particularly the Federal Renewable Energy Target rebate scheme and state-by-state feed-in tariffs), but what incentives are still available for solar hot water? There are both Federal and state-by-state incentives for the installation of solar hot water systems. These rebates, as well as the RECs that would become yours if you install a system, have been explained in detail in this previous blog.

Is it possible to get rebates and RECs for both PV and Solar Hot Water?

Provided you meet the eligibility criteria for both, there is no reason that you cannot claim rebates and RECs for both your PV and your solar hot water system.

Written by James Martin

Solar Choice Analyst

© 2010 Solar Choice Pty Ltd

Sources

http://www.environment.nsw.gov.au/rebates/ccfhwsfaq.htm#1

http://www.climatechange.gov.au/government/programs-and-rebates/solar-hot-water.aspx

(There is a new, up-to-date as of January 2011 blog entry regarding the Enhanced Renewable Energy Target here. If you have any comments or questions please see that article first!)

The Minister for Climate Change and Energy Efficiency announced today the schedule by which reductions to the Solar Credits Discount Scheme will be effected. If you’re fully installed by 1 July 2011 you’ll get the maximum benefit of the current discount scheme – otherwise the cost will rise by approximately $1,000 for an entry level 1.5kW system (presuming a $32 Renewable Energy Certificate (REC) value).

The good news is that a long term plan has been outlined in parallel with the original intension of the legislation to phase out the discount at a steady and calculated rate.

The Solar Credits Multiplier, which multiplies by five the number of Renewable Energy Certificates (RECs) that are allocated for the first 1.5kW worth of grid-connected solar energy installations in Australia, is to be reduced accordingly:

• 5x to 4x on 1 July 2011;
• 4x to 3x on 1 July 2012;
• 3x to 2x on 1 July 2013; and,
• 2x to 1x from 1 July 2014.

The only changes that have been enacted were to bring the commencement of the reduction in the multiplier forward one year. This reflects the original aim of the legislation to phase out the multiplier in correspondence with the lowering costs of manufacturing and importing of solar components and competitiveness in the solar installation industry.

In addition, the introduction of a minimum $40 value for RECs is to go ahead as planned. The Office of Renewable Energy Regulator (ORER) will not hold the authority to manipulate either of these guidelines when it sees it appropriate. This will grant further stability to the industry.

Given the recent cuts to the NSW State Solar Bonus Scheme and the past experiences of rebates and grants being cut without warning, the layout is being welcomed by the Industry. Legislation that allows for forward planning and anticipation greatly assists not only residential householders, but encourages steady and stable growth for the industry as a whole.

Written by Jarrah Harburn & Justine O’Neill

Solar Choice

© 2010 Solar Choice Pty Ltd

(For a bit more context regarding what RECs are, please see our previous entry on how to determine your Solar Credit discount.)

In a previous article (August) Solar Choice highlighted several key conferences that were focusing on renewable energy, and Solar Energy in particular. Improving technology and policy designed to deploy the hardware necessary to allow individuals to contribute to the energy revolution taking place has certainly grabbed the headlines like never before this year.

Solar Choice attended the recent All Energy conference and Exhibition in Melbourne (http://www.all-energy.com.au) and after an extremely busy October, especially in NSW, we thought we would share a few thoughts and highlights.

All-Energy Australia is the sister show to All-Energy UK, Europe’s largest all-renewables event which has now been running for 10 years.

Over 2 full days, there were 30 sessions and over 90 speakers from Industry and Government covering all the important issues in the clean and renewable energy industry in Australia today. Topics covered the whole spectrum of Energy with the calibre of speakers extremely high

There was also an exhibition running alongside the conference with 130 companies and organisations present. The majority were Australian, however there was a good overseas contingent, many introducing new technology into our market for the first time. They obviously see Australia as an attractive honey-pot that is worth investing in.

And it is!

Australia has so much potential to leap far ahead in terms of energy, if only the energy stars (tsars?) will align.

One thing that shone through was the highly mature and collaborative nature of the industry. The panel sessions, on topics such as Wind, Clean Coal, Electric Vehicles, Power Transmission, Bio-energy solutions to name a few, had a good mix of Government officials and representatives, Academics, Finance and Banking, and Company Executives sharing present (reality) and projected plans.

A common thread was the imperative to keep on improving policy and bureaucratic processes to allow the advancing technology and desire by business and the general population to invest in our energy future and play their part. Be it an interim Carbon Tax or ideally an ETS, something has to be enacted soon to allow Clean Energy and the over arching goal of atmospheric and oceanic CO2 reductions, to step up the next level.

In terms of Solar PV, there were three very good mini-presentations
¢ ACT’s Electricity Feed-in Tariff scheme; Simon Corbell, Minister for the Environment, Climate Change and Water and ACT Minister for Energy
www.solarcapital.act.gov.au for more information
¢ Project Phases for large scale solar installations http://www.conergy.de/desktopdefault.aspx/tabid-2115/2941_read-9540/ for recent large installations by presenters company in Germany.
¢ Design considerations for large scale solar PV was also covered.

The next All Energy conference and exhibition will be held in Melbourne at the MCEC, 12th and 13th October 2011.

Sam Bradley

Installer Network Manager, Solar Choice Pty Ltd

Shock News – but THERE’S STILL TIME

In a shock announcement an hour ago the NSW Govt has stated that the popular solar bonus scheme will be closed to all customers who haven’t paid a  deposit for their systems by midnight tonight.

We ask all our NSW customers who haven’t yet selected their installer and paid a deposit to act immediately, and before midnight tonight, if they wish to secure their entitlement to the generous 60c gross tariff.  Otherwise, if your deposit is paid after midnight tonight, the scheme will reduced to a mere 20c tariff. To assist you, nearly all installers in 0ur NSW network have reduced their deposit to a risk free $100.

The Govt press release is as follows: http://www.premier.nsw.gov.au/sites/default/files/101027-Solar-Bonus-Scheme_0.pdf

Installers are working up to midnight tonight to process your orders.  The Govt press release expressly states that the deposit must be non-refundable.

How to secure the 60c tariff? You still have time to proceed with our fast online system.

1. Go to your Solar Choice Quote Comparison, or automatically generate a fresh Quote Comparison (which will be emailed to you within a minute) by completing the form on our homepage.

2. Select your installer and click “Pay Deposit” for your preferred option.

3. Follow the simple instructions to accept the terms and nominate “Electronic Funds Transfer” for deposit payment. Do not select credit card or cheque, as your order may take too long to process. Click proceed to generate a pdf of the Accepted Quote which will then be promptly emailed to you, your installer and Solar Choice.

4. You will then automatically be given an email with the Account name, BSB and Account number for the installer you’ve selected.

5. Pay your deposit by EFT asap. KEEP A RECORD OF YOUR PAYMENT RECEIPT AND TRANSACTION NUMBER.

6. You and your selected installer then have 21 days from midnight tonight to lodge your application to be connected with a gross meter.

Continue to follow our blog today for further updates.

The Solar Choice Team

Once you’ve understood the benefits behind Solar Panels you might go ahead and install one on your roof through us here at Solar Choice but that’s not the end of the job really.

One thing you might want to consider after you’ve installed your system is “installed-system-efficiency”, which is the concept of actual efficiency of the system taking into account the specific location of your solar panel. This can be calculated by measuring how much power is coming out of your solar panel over time and comparing it to regional data and this will allow you to identify areas of loss similar to the areas we talked about in “How does my solar panel perform over time”.

For example:

• When noticing a steady weekly decline of 30-70 watts (5% of rated capacity) this might suggest is that you might need to wash your panels as there is a potential accumulation of dust on your panels.
• When noticing a seasonal decline in performance this might suggest that your neighbors trees are getting in the way of the direct sun-light
• Finally when noticing a very low seasonal average or a great difference compared to the values from the Bureau of Meteorology in the winter or summer months you might want to talk to the installation company to see if they have installed your panels to the appropriate angles. Or it could even tell you if your panel is broken…

So what are your options?

1) Go out and buy a pyronometer and a voltmeter and measure the daily radiation and your daily output.

or

2) Subscribe to a service that allows you to monitor your output through the internet or even easily accessible through an iphone application!

Written by Prateek Chourdia

MEngSc – Photovoltaics and Solar Energy, UNSW

Solar Energy Analyst

Solar Choice

© 2010 Solar Choice Pty Ltd

Note: If you do choose option 1) then I strongly suggest that you don’t do it alone and that you seek the advice and help of a certified electrician.

The ACT government has announced the first large scale feed in tariff in Australia. The scheme puts ACT in the premier position for investment in medium and large scale solar generation. This commercial feed in tariff has an overall goal of 240 MW of generating capacity which is staggered over three levels:

1. Large scale generation category for generators larger than 200 KW (category cap of 210 MW)

2. Medium scale generation category for generators between 30KW and 200kw (category cap of 15 MW)

3.Existing micro generation category (household rooftop) up to 30KW (category cap of 15 MW)

The pricing rate of the large scale generation scheme will be put to auction to allow market forces to provide the most economical value for the implementation of this scheme.

This long awaited announcement  (ACT media release) once again sees the ACT leading the states and territories in adopting the highly successful and beneficial solar feed in tariffs.

Written by Iain McGregor

Commercial Tenders Manager

Solar Choice

© 2010 Solar Choice Pty Ltd

Stand-alone (off-grid, remote power) systems tend to require significantly more caution, care, and maintenance than grid-connected systems, where you can plug in and use any appliance you want without having to think about the consequences–there usually aren’t any! 

The reason for this is that AC (alternating current, as opposed to DC, direct current) is the electricity flow type of choice in the grid-connected world, and the vast majority of household appliances have been designed with AC circuits in mind.

Today we’re going to talk a little about AC vs DC and associated power measurements.  The difference between the two is something you’ll have to know a bit about if you want to make the best use of your stand-alone PV (photovoltaic) system.  The main difference is that with DC electricity, the electrons (the power) flow in one constant direction, while with AC electricity, the electrons ˜alternate’ back and forth at mind-bogglingly high speeds.  Two of the key advantages of AC electricity are that 1) power losses are less than with DC when AC power is transmitted over long distances, and 2) AC voltage can be relatively easily ramped up or down using devices called transformers; DC, by contrast, loses more voltage (and therefore power) over long distances, and its voltage cannot be easily altered to suit whatever appliance you may happen to be using.

˜Whoah!  Slow down!  Power?! Voltage!?  Is there even a difference?’ you might be thinking to yourself in puzzlement (or you might not, in which case feel free to skip this paragraph…)  There is indeed a difference between power and voltage, but they are related.  We can see this relationship in a simple equation:  Power = Voltage * Current, or W = V * I.  Power is usually measured in Watts (W), Voltage in Volts (V), and Current (symbolised by œI but measured in Amperes œA).  It is convenient to think of voltage as the ˜pressure’ of the electricity and current as its ˜flow’, a bit like water being forced through a pipe.  The water metaphor holds up pretty well in the case of DC, where it’s easy to imagine the water flowing in one direction, but becomes a bit more difficult to visualise with AC (can you imagine the flow of the water switching directions 50+ times/second?)  The measurement of this alternation, called ˜frequency’, is measured in Hertz (Hz) and is not applicable to DC electricity.  In Australia, for example, wall socket frequency is set at 50Hz (AC, of course).

So how is any of this relevant to you and your on or off-grid system?  There are lots of reasons.  The flow of energy produced by a solar/PV array is unidirectional–DC.  The same is true for all batteries.  The problem is that many appliances, including anything that contains a motor (your washing machine, electric razor, etc), will only function on an AC circuit, and most other appliances are designed for AC anyway because it is the standard for home electricity.  (If you want appliances specifically for DC circuits, you have to ask for them!)  For this reason, your solar/PV system needs an inverter, which will convert the DC from your batteries and PV array into usable AC electricity–so you can run your washing machine and so on.

Unfortunately, converting DC to AC can come at the cost of energy efficiency.  The conversion efficiency ratio is known as the ˜power factor’ (PF), and differs from appliance to appliance.  AC appliances are rated with a power factor between 0 and 1.  This is essentially the efficiency of the conversion from DC to AC electricity, where 1 is 100% or ˜unity’ with the DC power equivalent.  Where does the efficiency loss come from?  It’s a bit technical, but it has to do with whether the current and voltage are ˜in phase’, meaning that they are alternating at the same rate.  (DC electricity has no phase, so this problem doesn’t arise with DC.)  DC power is usually expressed in kVA (kilo Volt Amperes), known as ˜apparent power’.  Since there is no phase to factor in, with DC,  kVA = kW.  In AC, however, the ˜real’, ˜true’ or ˜actual power’–the amount of power the device can be observed to be using–is actually less than the ˜apparent power’.  The balance is lost in excess current–it’s there, but doesn’t do any useful work, and hence is not ˜real’.  AC power can be expressed in the equation kW = kVA * PF.

Different types of devices have different PFs.  The following chart provides a very rough guide to typical PF values, but for exact numbers you’ll need to inspect the device you intend to use or consult its maker.  As you can see, some devices are ˜power factor corrected’ (PFC) in order to reduces the losses inherent in AC/DC conversion.  You can also see (in the image up top) that resistive devices suffer no drop in efficiency from the conversion.

In an off-grid system, it is possible to run some of your AC devices, such as incandescent light bulbs or soldering irons directly from your batteries without passing through the inverter.  Additionally, it is possible to get appliances such as refrigerators designed specifically for DC electricity flows.  A direct DC setup could save you energy and money in the long-run, but you’ll have to get your installer/electrician to set up a separate circuit up for you.  Ultimately, it will be up to you to determine whether the energy savings achieved by using a DC circuit will be worth the cost of having it installed and buying the DC appliances!

Written By James Martin

Solar Energy Analyst

Solar Choice

© 2010 Solar Choice Pty Ltd

Sources:

http://www.differencebetween.net/science/difference-between-kva-and-kw/

http://www.wisegeek.com/what-is-the-difference-between-ac-and-dc.htm

http://www.powerstream.com/cv.htm

Earlier today the NSW Govt invited submissions from the solar energy industry and members of the public on what changes, if any, should be applied to the immensely popular Gross Feed In Tariff (or Solar Bonus Scheme).

Submissions need to be lodged by 30 September 2010.

Thankfully the NSW Govt hasn’t imposed any sudden changes. The Minister has made clear that customers already connected to the scheme, or who will have their gross meters approved by their electricity wholesaler prior to any legislative changes (if any), will not have their entitlement to the scheme’s generosity affected.

Solar Choice anticipates that demand in NSW for solar energy installations will surge on this news, and recommends that customers err on the side of prudence and proceed with their preferred installer as soon as possible to avoid any risk of missing the 60c per kW hour gross tariff.

Angus Gemmell
National Sales Manager
Solar Choice Pty Ltd