Category: Solar Electricity

Update on Solar Power, and Tariffs

To get the best benefit from Grid Connected Solar Power you need to be up to date with the latest tariffs that apply to your installation.

These days the Feed In Tariff (FIT) is much less than a few years ago.

Power Tariffs

Here in Victoria the FIT for excess power put into the grid for new installations is $0.062/kwhr.

The above rate will also apply to existing installations that:

  • Are coming to the end of the initial scheme that had a higher FIT.
  • Have been eligible for a higher FIT but want to increase the number of panels.

This compares with my current tariff for power consumption of $0.248/kwhr. (I could get lower ‘Off Peak Power’ but it is a balance between paying more for ‘Peak’ and less for ‘Off Peak’)

Although these rates are specific to me the general relationship will be similar for most locations in Australia.

Change Your Usage Patterns

To maximise the benefit from the current tariffs you need to ‘Change Your Usage Patterns’ to maximise the use of the solar power when it is being generated.

To achieve this, during daylight hours, you should aim to:

  • Wash and dry clothes. (although drying clothes on the line is better than driers).
  • Cook meals and bake, for electric ovens, and cook tops. (or use a ‘Crock Pot’).
  • Run your swimming pool filter.
  • Recharge battery appliances.

When you are planning to change your usage patterns remember to stagger the operations times so you are less likely to exceed the output of the panels.

Although this does minimise power going to the grid. . . the real purpose is to minimise your power used when the panels aren’t generating and you are importing from the grid.

Consider Panel Orientation

If you are planning a new installation there are real benefits in installing a panel that will give maximum power generation when you would normally use the power.

For most of us that will mean considering a more Westerly Orientation, rather than the traditional north facing orientation.

This will means that you will be best placed to use the ‘Free’ Solar Power from, when you come home, until sunset.

If you find you use more power in the morning, then East facing panels would be of benefit.

 

See Solar Electricity for more posts

 

Solar Power – Inverters

What Are Inverters?

Basically an inverter is a device which converts the electricity from your solar panels to a form that can be used by normal domestic appliances, and lights.

The electricity generated by the solar panels is Direct Current (DC) but the typical home runs on Alternating Current (AC)*.

*It is possible to run a home on DC electricity without an inverter but you will need to buy special appliances, such as those designed for caravan use. The wiring requirements are also quite different!

Types of Inverter Applications

There are three types of inverter applications which all require different types of inverters, which are:

Stand Alone Inverters

These are used for houses that are not connected to the local power grid. The solar panels charge a bank of batteries by Direct Current. When an appliance is switched on the inverter converts the DC electricity from the batteries into AC power.

This is a relatively simple form of inverter, and the system as a whole has the following characteristics:

  • No power bills.
  • Unaffected by power cuts.
  • Initially expensive due to the cost of a large bank of batteries.
  • You may need an auxiliary power supply such as a generator for long periods with little sunlight.

Grid Tie Inverters

The most common form of inverter these days. The solar panels feed Direct Current into the inverter which converts the electricity into AC power. The power is then used by any appliances that are on, with excess electricity being ‘pushed’  into the grid. (You will be credited for this electricity) If electricity demand greater than the solar panels can provide power is taken from the Grid.

  • Reduced power bills.
  • A power cut will result in complete loss of power.
  • Lowest cost solar power system.

Dual Inverters

Also called Battery Backup Inverters. The solar panels charge a bank of batteries by Direct Current with the batteries providing power to the house in a similar manner to the standalone system. When the batteries are fully charged any excess  power is ‘pushed’  into the grid. (You will be credited for this electricity)

This is the most complex and expensive type of inverter, The system as a whole has the following characteristics:

  • Reduced power bills.
  • Unaffected by power cuts for several hours (depending on battery capacity).
  • Mid range cost. Although the inverter is expensive there are typically far fewer batteries than a stand alone system.

 

See Solar Electricity for more posts

 

Solar is Winning

Electricity demand has dropped so much that Australia currently has at least 3 major coal fired power stations more than it needs! (This year the surplus capacity at peak demand is estimated to be around 8,000 megawatts)

In early July this year there was actually zero demand for power station generation in Queensland, mainly due to an estimated power output of 600 megawatts from rooftop solar.

A report by the Australian Energy Market Operator have warned that the electricity generation market is close to breaking point.

Electricity demand, which has been dropping since 2009, will continue to drop for at least the next three years. The closure of major industries such as aluminium smelting and car manufacture is only likely to further decrease demand.

Why Aren’t Power Prices Dropping?

In most ‘Free’ markets when demand drops so do prices.

While demand has been over the past few years electricity prices have doubled . . . . and don’t think that’s mainly the Carbon Tax!

Over 51% of your bill is for Network costs (Federal Treasury Estimates)

When the Goverments’ privatised electricity they allowed the Power Companies to recoup their investment in network upgrades by increasing their charges.

The networks have spent over $45,000,000,000 in the last five years to meet an ‘Increasing Demand’ which we are all now paying for in our bills.

The ‘Joke’ in all this is by increasing their prices the electricity companies have made their ‘Main Competion’, Roof Top Solar, more attractive!

What Now

So after 5 years of getting everything wrong are the power companies interested in doing the right thing? . . . . Like investing in generating power from renewable resources that work when the sun isn’t shining?

No they are lobbying the government to wind back the renewable energy target!

It’s no wonder that some people with solar panels are talking about disconnecting from the grid!

For more informaton click on this link from the ABC: The Price of Power

 

 

Solar Power – No North Facing Roof

Conventional wisdom has been that you needed a North facing roof to mount your solar panels . . . . . . but it might be time to re-think!

Cost of Panels

In the early 1990 when people first really started looking at solar power for the home the cost of  pv panel alone was in the order of $7-8/watt and installation efficiency was very important.

Now with panels costing less than $1/watt, installed, adding a few extra panels isn’t as big an issue as it used to be.

Efficiency

The efficiency drop  off from moving away from a North facing roof is not as much as you might think.

For instance panels on a roof facing either East or West can still produce more than 80% of the power of a North facing panel. (see Solar Alignment for more information)

More Effective Spread Of Power

A few years ago we were paid for every watt we put into the grid, at more than it cost to buy a watt from the grid. This meant that systems that produced lots of power when we weren’t using that power (typically around noon) had real advantages.

For new systems you are now typically paid less for every watt you produce than a watt costs to buy. It therefore makes sense to be generating power when you need it across the whole day so you use as much of the solar power yourself.

A couple of options are:

  1. Split the panels evenly between say Westerly and Easterly facing it you are looking for an even spread of power across the day.
  2. Concentrate on westerly facing if your main power use is in the afternoon and evening.

A Few Final Points

  • Although this post has been mainly written for grid based systems there will be some benefits for more even power generation for stand alone systems, as it could reduce the battery discharge cycles,
  • In the past, to maximise efficiency, systems were built with mechanical trackers to follow the sun. With the current low cost of panels I don’t think trackers can be justified due to cost and increased complexity.

Also see West Facing Solar Hot Water

Solar Electricity – Retirement Investment

Downsizing to a smaller new house for your retirement?  Don’t forget to think about solar power.

Last week I revised a post ‘Solar Power is it Worth It?‘  but if you are approaching retirement, like me, there can be an even bigger financial advantage in having solar installed.

Differing Lifestyle

Because we are both out at work during the weeks I calculated that with a 1.5kw system costing around $3,000 panels we will save:

      • Weekdays $1.09
      • Weekends $1.40

See the original post to see how I arrived at these figures

After retirement its likely that our weekday usage patterns will be more like the weekends so our annual savings are expected to be 365 x $1.40 = $511.

Effect on Pension

I am assuming that you will have some money from superannuation, but not enough to mean you won’t be eligible for a state pension.

If you have more assets then the Government limits your pension. It will be reduced by $39 per annum for every extra thousand dollars. (Basically the government takes the interest)

Invest $3,000 in a solar power system and that becomes part of your house, which is excluded from the governments asset test. You will therefore be eligible for an extra $117 a year pension.

Summary

The expected benefit for your $3,000 investment is:

$511 + $117 = $628.

20.9% Return with a Payback of Under 5 years

I don’t know about you but i’m hoping to live a lot longer than 5 years beyond retirement!

For more about solar panels see Sustainability, Solar Power

To see an updated review see Cost / Benefits

 

Solar Electricity – Is It Worthwhile? (2014)

There is a lot of marketing information around about Grid Connected Solar Panels but not many independant facts. Here’s an example of an evaluation of a basic system for a house.

  • We use around 16kw hours (kwhr) of electricity per day which is fairly typical;
  • For each 1kw of solar panels we can expect to generate around 1300kw hours per year that’s an average around 3.5 kw hours per day;
  • For a basic 1.5kw system we should generate on average about 5.2kwhrs;
  • Our current tariff for power is $0.3152 /kwhr regardless of time of day;
  • I have done the evaluation assuming that any surplus power is sold back at$0.08/kwhour.

How Much Will Be Saved?

Weekdays (as we both work and the house is empty during the day) we should be able to put at least 2.5 kwhrs into the grid and use a maximum of 2.7kwhrs running fridges etc)

Income 2.5kwhr @ $0.08 = $0.24

Saving 2.7kwhr @ $0.3152 = $0.85

Benefit = ($0.24 + $0.85) x 260 days = $283

Weekends we probably will only put 1kwhr into the grid as we may well be at home using power for TVs, heating or cooling, etc.

Income 1kwhr @ $0.08 = $0.08

Saving 4.2kwhr @ $0.3152= $1.32

Benefit = ($0.08 + $1.32) x 104 days = $145

Total annual benefit is $428.4

Is it worth it?

Well there are some 1.5kw systems being advertised now with various rebates which cost less than $3000.

If you had $3000 on term deposit returning 4% that’s $120 a year, which would then be taxed. Alternatively if you put the cost on your mortgage that will mean that you are borrowing $3000 at a rate of around 6%. That’s costing around $180.

From these figures it looks like for the basic system you will be around $250-$310/year better off.

NB. I first did a Cost Review in 2011. Since then the cost of panels, and the government subsidies, have gone down. The cost of power from the grid has gone up. The overall financial advantage is around the same.

 

To see an updated review see Cost / Benefits

 

For similar posts see Solar Electricity in the Sustainability Tab

 

Why I Don’t Have Mono-Crystalline Solar Panels


Several people have commented that my panels look different to those on other houses.

Most solar PV installations use Mono-Crystalline panels, because they are smaller for the same power rating.

The panels on my roof are Kaneka Thin Film Panels.

Here are the reasons why:

Efficiency In Real World Temperatures

When you see a panel power rating it is based on laboratory conditions with a panel temperature of 25oC.

In Australia, on your roof, the panel temperature is generally somewhere around double the ambient temperature, thus most panels operate above 25oC most of the time.

Typical crystallines panels lose power @ 0.45% per degree C above 25oC.

Typical thin-film panels lose power @ 0.25% per degree C above 25oC.

This means that on a typical 25oC day with a panel temperature of 50oC

  • A 1000watt mono-crystalline system may be generating 885watts.
  • A 1000watt thin film system is likely to be generating a higher power of 935watts.

On hotter summer days when panel temperature can rise to over 80 degrees the difference will be even greater.

Shading

Thin film panels are bigger than mono-crystalline panels means that more of your roof is shaded by the panels helping to keep the house cooler.

Energy Payback

Thin film panels have much lower embodied energy than mono-crystalline panels meaning that the energy involved in the production is recovered within two years of use.

Better Performance When Partially Shaded

Partial shading effects can be quite significant in overall system efficiency. Thin film panels however are less susceptible to shading.

Cost

In spite of the above advantages for Thin Film panels the cost per installed watt is around the same as Monocrystaline panels.

More independent information about solar panels in Australian conditions can be found at the Desert Knowledge Solar Centre at Alice Springs

 

For similar posts see Solar Electricity in the Sustainability Tab

 

Types of Solar Panels for Electricity

From some of the adverts you see you would think there is only one sort of solar panels…. in fact there are several alternatives.

The type of panels generally available are:

  • Monocrystalline solar panels The highest cost but the most efficient with a long history of use.
  • Poly-crystalline Similar to mono-crystalline panels, but the silicon used has a different structure which is easier to make and therefore cheaper but less efficient in watts per m2.
  • Thin-film This includes several technologies of which the latest is CIS. These panels are the usually the lowest cost panels but can be twice the area of a Monocrystalline panel for the same output.
  • Hybrids There are also a number of hybrid panels around which combine different technologies to improve all round performance.

Don’t get too confused by the marketing hype and the quoted efficiencies.

Unless you are have limited space to put the panels the best panel is the one that produces power at the smallest price per watt and will continue to do it for the longest time.

An advantage of having larger, but lower efficiency, panels is that more of the roof is shaded by the panels in the summer. This will reduce the heat gain in the roof space, saving on cooling costs.

The only times that efficiency becomes important is when;

  1. You are running the whole house off panels and you need more area for low cost panels than you have got roof area – more for off grid applications.
  2. You only have a small North-facing roof.
  3. The roof is Badly Shaded.

As well as the cost per watt you should also looking for panels from reputable manufacturers that come with a long guarantee (Up to 25 years). Additionally you would be advised to ask for a 5 year installation guarantee. 

 

Solar Electricity – Is It Worthwhile? (2011)

Since this post was written in 2011 there has been many changes; in subsidies, the cost of systems, and  Power Supplier charges. For the  an updated post see:  Solar Electricity – Is It Worthwhile? (2014)

There is a lot of marketing information around about Grid Connected Solar Panels but not many facts. Here’s how I evaluate a basic system for a house in a Melbourne Suburb.

  • We uses around 16kw hours (kwhr) of electricity per day which is fairly typical;
  • For each 1kw of solar panels we can expect to generate around 1300kw hours per year that’s an average around 3.5 kw hours per day;
  • For the basic 1.5kw system we should generate on average about 5.2kwhrs;
  • Our current tariffs for power is $0.2025 /kwhr regardless of time of day;
  • I Have done the evaluation assuming that any surplus power is sold back at the peak rate. Some states have attractive buy back rates that will improve your financial situation.
  • As part of going solar our tariffs will change to:
    • $0.2625/kwhr peak times (7.00am -11.00pm Monday to Friday, 80 hours per week)
    • $0.1075/kwhr off peak (all times other than peak, 88 hours per week)

How Much Will Be Saved?

As we are out of the house for at least half the peak period the cheaper off peak power should more than offset the more expensive peak power so our average power cost should remain similar to our current tariff.

Weekdays (as we both work and the house is empty during the day) we should be able to put at least 2.5 kwhrs into the grid and use a maximum of 2.7kwhrs running fridges etc)

Income 2.5kwhr @ $0.0.265 = $0.66

Saving 2.7kwhr @ $0.2625 = $0.70

Benefit = ($0.66 + $0.70) x 260 days = $353

Weekends we probably will only put 1kwhr into the grid as we may well be at home using power for TVs, heating and cooling, etc.

Income 1kwhr @ $0.265 = $0.265

Saving 4.2kwhr @ $0.1075= $0.45

Benefit = ($0.265 + $0.45) x 104 days = $74

Total annual benefit is $427

(I believe my calculations have been fairly conservative and the actual benefits could be higher) PLUS For every $0.01 of premium rate buy back you will get another $6.24 per annum.

Is it worth it?

Well there are some 1.5kw systems being advertised now with various rebates which cost less than $3000.

If you had $3000 on term deposit it would now (Jan 2010) be returning 6% that’s $180 a year, which would then be taxed. Alternatively if you put the cost on your mortgage that will mean that you are borrowing $3000 at a rate of around 8%. That’s costing around $240.

From these figures it looks like for the basic system we could be around $187 better off. Even more if you spend less than $3000 or can get a premium buy back rate.

If you are looking to get a system you need to know that there may additional charges for things like:

  • Installation on a tiled roof;
  • Frames on a flat roof to provide the best angle for the panels;
  • Split array over two different sections of roof;
  • Lifting and access if you have a 2 storey houses;
  • and travel charges if you are outside the metropolitan area.

For similar posts see Solar Electricity in the Sustainability Tab

 

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