Category: Solar Electricity

Which Way Is North?

Don’t rely on a compass!

Or a mobile phone either!

There are different Norths

  • True North
  • Grid North
  • Magnetic North

The difference can be more than 10 degrees which can affect your view and the solar performance of your house and solar panels.

Just to make it more complicated the difference can change depending on where you live and the date!

True North

True North points to the North Pole, the axis of the earth’s rotation.

Grid North

Grid North is the basis of the grid lines on a paper map as your north reference.

Grid north is typically close ( within 2° east or west of true north) and varies with your position within a zone.

It is used when establishing geographic co-ordinates so it will be the direction the North Arrow points on a house plan prepared for construction.

Magnetic North

A compass needle will align with the earths magnetic field and thus points to the ‘magnetic’ poles.

The Earths magnetic field and thus the ‘Magnetic Pole’ moves over time.

The difference between Magnetic and True North (called Declination) is also different depending on your position.

 

Want to find the difference for your site? . . . . Follow this link:  Geoscience

Solar Citizens

Do you want to be a Solar Citizen?

Do you know who the Solar Citizens are?

 

Well I only found out about them a couple of weeks ago.

Basically they are a nationwide group of people that support a more sustainable future.

Amongst other things they are campaigning for are ‘Better Feed In’ rates for people with Soalr PV panels on their roof . . . . they believe a fair rate for Feed In Tariffs is between $0.10 and $0.18 rather than the $0.05 to $0.08 you might be currently getting!

 

To find out more follow the link below

www.solarcitizens.org.au

Three Reasons Why Natural Gas Isn’t Better Than Electricity

With all the publicity about rising gas prices the gas networks must be feeling the heat. (AAAARGH what a shocking ‘Dad’ Joke)   

Why else would I find an article on my Facebook feed entitled ‘Three Reasons Why Natural Gas Is Better Than Electricity’   

Like a lot of advertising there is a fair bit of Bull Dust around so lets look at what they say, (with my comments in Italics afterwards)

1. It’s always there when you need it

Natural gas infrastructure allows distributors to deliver gas to customers on demand, without the supply and reliability issues associated with electricity. In fact, when it comes to reliability, Australia’s natural gas network experiences only one unplanned outage, on average every 40 years.

But when it happens it can be a big one!  After the Longford Gas Disaster in 1998 the Whole of Victoria had no gas for more than 2 weeks. Daily cold showers over that one period was worse than the total of around 50 hours (say 2 hours a year) of power cuts over the last 25 years!   We were just happy that we didn’t have gas cooking.

Also what about these articles on the upcoming   Gas Shortage   that forced Malcolm Turnbull to step in

 

2. It’s up to 40% cheaper than electricity to use

Natural gas has always been consistently affordable and is likely to continue to be so well into the future. Unlike electricity, where increased consumption drives your tariffs higher, generally the more gas appliances you install the more you can save. This is because in most cases, the cost per unit of gas decreases as consumption increases.
While gas appliances may cost a little more to install initially, running costs are generally lower. This means that using natural gas almost always works out cheaper in the long run.
For example, take one cook top and hot water system running in an average Australian household for one year:

  • Running on electricity, the cost would be $1,156 p.a. in South Australia and $1,235 p.a. in Victoria.
  • Running on natural gas, the cost would be $782 p.a. in South Australia and $725 p.a. in Victoria.

Installing a heat pump would save 50 – 60% of the electricity costs. That would bring electricity costs down to below gas.   A solar hot water system with electric boosting could save more . . . . and think of the savings if you could get rid of the gas standing charge!

3. It produces significantly less greenhouse gas emissions than electricity

Yes, natural gas is a fossil fuel, but it is also far more environmentally friendly than electricity. Its chemical structure is quite different to coal, meaning its emissions are much lower.
Here are some quantifiable examples of why natural gas is a better environmental choice:

  • In South Australia, a gas powered hot water system emits 67% less CO2 than an electric equivalent
  • In Victoria, a gas powered hot water system emits 83% less CO2 than an electric equivalent
  • The emissions from a natural gas powered hot water system is on par with those produced by a system using 50% renewable energy and 50% coal electricity mix.
  • Gas currently delivers 44% of Australia’s household energy, but only produces 13% of household greenhouse gas emissions
  • Gas has a higher yield rate* from extraction to delivery (90%) compared to electricity, making it far more efficient.

With either of the alternatives mentioned in my response to Point 2 above the CO2 for electricity drops dramatically.   I also have 3kw of solar panels on the roof of my 2 bedroom unit,  on current performance it looks like I will be generating more power than I consume* . . . . Net effect no CO2 generated.

Although gas does have a higher yield rate what they don’t say is gas appliances have a lower efficiency typically 70 – 90% compared to electricity. Even the most basic electricity heater is 100% efficient. Some heat pumps are better than 300% efficient (for every kw going into the unit it delivers 3kw of heat)

Conclusion

If you want good advice on hot water, cooking, and heating your property don’t rely on the gas networks (or the electricity networks) . . . . find some independent advice, like this blog.

 

* Between when my solar system was switched at the end of January 2017, and 15th May 2015, I have generated 510kwhrs more power than we have used. I know I won’t be generating as much for the next few colder months, but I did miss out on a peak generating month of January.

 

Solar Power – High Grid Voltage

One problem with solar systems that I only found out about after my solar system was installed is the effects of ‘High Grid Voltage’.

How I found out

The system that I bought had a Fronius Inverter which includes a quite comprehensive monitoring and reporting program.

Soon after the system was installed I started getting e mail reports with the following message: “4 – Gradual voltage dependend power reduction” with a time and date.

The time and date coincided with power output drops like the one shown in the graph below. (at around 10.30am)

This output drop occurred on a cloudless day.

On talking with the systems supplier Essential Solar they were able to access the inverter’s data and identify the problem as High Grid Voltage.

Grid Voltage

I must say when I thought about grid voltage at all I thought it was around 220-240 volts.

Australian Standard AS 60038 however, says the nominal mains voltage is 230 volts. . . . .  what that means is 230 volts +10%, – 6%, i.e. 216.2 to 253 V.

In practise the electrical distributors seem to set their systems up to run above 230 volts.

The problem is that if the grid voltage exceeds 254 volts a modern inverter is designed to throttle back, and shut down at 255 volts.

In my case the grid voltage was typically around 253 at 6.00am in the morning.

As soon as my solar panels, and the panels of my neighbours, started to generate the extra power pushed into the grid caused the voltage to rise further.

Solution

Once the problem was identified Essential Solar took up my case with the Electrical Distributor (who is legally required to ensure that the voltage stays within the 216.2 – 253 volt range)

The solution however does take some time as follows:

  • A week for the electrical distributor to install voltage monitoring equipment on our local substation.
  • 2 weeks of monitoring the voltage.
  • 1 week to evaluate the results,
  • 6 weeks (30 working days) to install equipment to ensure the voltages will in future be within the required range.

 

Why I Didn’t Want A Tesla Battery

I recently posted about my experiences of getting quotes for Solar Power (Obtaining Quotes) and one of the questions I have been asked is “Are you getting a Tesla Battery?”

Here are my reasons why not

Tesla Battery

The total installed cost of a Powerwall 2 battery is being quoted at $10,150.

With 13.5 kilowatt-hours of storage that means a cost of approximately $750 per kw hour that’s quite an effective price.

Background

My solar system is limited by suitable roof space to just over 3.00kw

The estimated power generation is around 4000kw hours  a year with a monthly average in summer of 16kw hours a day.

In winter it is much lower at an average of 6 kw hours per day.

Evaluation

Prior to the solar installation we were using about 7- 8 kw hours/day without using air conditioning. and another 4-5 kw hours with air conditioning.

It would probably be more if we were home all the time but we both have part time jobs.

In Summer we have a lot of excess solar power, but we are only using  2 – 4 kw hours of grid power when the panels aren’t generating so the battery will only save us around 2 -3 kw hours per night.

In winter we won’t have much excess power during the day so I would estimate that we will only be able to put 1 – 2 kw Hours per day into the battery which will get used up every night..

Overall it looks like we would probably average 2kw hours, or less, of power from the battery a day.

With our supplier, Powershop, the benefit of using power from a battery is approximately $0.25 /kw hour (The difference between the ‘Feed in rate’ and the ‘Anytime rate’)

Our saving = Days in the year x Average kw hours saved x Benefit from battery use

= 365 x 2 x $0.25

= $183 per annum (a rate of return of less than 2% on the $10,000 investment)

This is a much worse rate than overall solar installation . . . see Reviewing Solar 

Conclusion

With battery life guaranteed for 10 years you won’t be seeing any real savings, not even if the battery lasts a further 5 years.

If Tesla, or someone else, were to offer a battery system with a quarter of the capacity(say 3kw hours) for a quarter of the price ($2500) I might get excited.

If you have got a lot more panels and a high evening, and night time use, then a Tesla Battery may work for you.

Review of Solar Cost / Benefits

In our new house we hadn’t got solar so I thought I would review  the financial advantages of installing a system.

I found a useful calculator on Solar Quotes a great site with lots of useful information.

Working through the Solar Quotes Solar Power Calculator I came up with the following for a 2kw system.

Calculator Input

2kw system in Victoria

Expected use – 50% of output

Calculator Output

Installation Cost $3900

Power generated 2628 kilowatt hours

Saving in first year  $340

That’s around an 8.5% rate of return , better than I could get at the bank,

If we use more than 50% of the power  the rate of return will be even better.

Is it worth upgrading?

An extra 1kw system would cost around $550 extra and generate an extra 1314 kilowatt hours

If the whole of the extra panels output went just to feed in tariff at $0.06/kw hour the figures it would save me $78,84.

That’s a 14% rate of return.

Our System

We decided to go with a 3.3 kw system with 13 Panels.

Eight panels facing North, and five panels facing west to maximise late afternoon and evening performance when we get in from work.

Expected saving from our $4,450 system = $340 + $78.84 = say $418 (a 9.4% rate of return)

Why Solar Makes More Sense for Retirees

Currently both my wife and I are semi retired and only working part time.

We currently have a considerable amount of money in Superannuation and other savings

In January 2017 as a result of government changes to pensions the amount payable to us when we reach pension age will be reduced by $3/fortnight ($78 per year) for every $1,000 of assets we have over  $375,000.

Money spent on the house is excluded from the asset test.

Financial Situation in Retirement

So for us

By investing our $4,450  in solar rather than leaving it in the bank we have lost $133.50 interest (best bank deposit rates currently are around 3%)

We stand to gain $347.1 in extra pension payments ($78 x 4.45)

Net income gain = $347.10 – $133,50 = say $213.

Add to a the power savings identified above gives

Overall Annual Return    = $213 + $418

= $631 (14% rate of return) . . . . and unlike money in the bank these benefits will keep up with inflation!

Should You Get A Micro Inverter Solar system

I’m just in the process of getting a solar power system for my latest house.

One of the changes since I last bought a system is that micro inverters are now more common than they used to be…….so I thought I would do some investigation.

What Are Inverters

Basically the solar panels produce Direct Current (DC) Electricity.

The DC electricity needs to be converted to Alternating Current (AC) and matched to the Grid.

Basically the inverter is a box of electronics that carries out this task.

Difference between a Traditional Inverter and a Micro Inverter

A traditional inverter is a single box, on the house wall, that combines the electricity from each ‘String’ (group of panels) and does the conversion in that box.

When you have a micro inverter system each panel has its own inverter which is mounted on the panel of right next to it on the roof.

This photo shows an Enphase micro inverter, one of the more common types available in Australia

System Differences

  • Probably the first difference that most people will notice is that a Micro Inverter system will be around 20% more expensive.
  • One of the issues with a Traditional Inverter is that if one panel in a string is partially shaded it affects every other panel in the string. (if one panel fails all the panels in that string will stop working) This means that a micro inverter system can be more efficient.
  • The cables on the roof will run at a much lower voltage with a Micro Inverter making it safer.
  • If a micro inverter fails it means you will have to get on the roof.

So What Did I Pick

With only the two of us we decided that a 3kw system would be big enough.

Looking around the house there are no trees or other shading to affect the panel locations.

We therefore decided that the traditional inverter system would be fine as far as efficiency is concerned.

With 2 strings each limited to 1.5kw we thought the voltages wouldn’t be unacceptably high.

 

 

 

Keeping Solar Panels Clean

I saw this solar panel with the sharp jagged plate on the top edge to stop bird perching the other week.

So I thought it was a good reminder that solar panels aren’t just fit and forget. . . . if they get dirty performance will go down

Here are some of the issues:

Bird Poop

The main issue is birds perching on the top edge so either a wire, spikes, or a plate like this one will reduce the risk.

General Dirt

You will know that all windows get dirty over time so its the same for solar panels.

Having a reasonable slope on the panels is a good start so rain will wash away the majority of dirt.

It may also be worth investing in one of those glass shield products that makes the glass ‘smoother’.

Lichen

People on the Alternative Technology Forum have found this can be a problem.

At the very least it could be worth aiming to inspect the panels once a year and give them a clean.

Off The Grid In Little River

Is living off the grid realistic?

To find out I recently visited an open day of this “Off The Grid’ House in Little River, Victoria.


All the electricity for this large 38 square 4 bedroom house are generated from solar panels on the garage roof.

The 30 north facing panels can generate up to 5.5 kilowatt.

The power is stored in a 48v battery bank that can provide around 22 kilowatt hours per day.

The Battery Bank is a little bit bigger than a standard chest freezer. . . much smaller than I expected.

On the October day I visited the battery bank was already 98% charged at 10.00am, so already recovered from the overnight power use.

Want to find out more? . . .  then visit this link:  theoffgridsolarhouse.com

Solar Panel Alignment (Revised 2015)

The suns position in the sky varies throughout the year and over each day.

The ideal situation is when the sun is hitting the panels closest to a perfectly perpendicular angle (90°).

So in Australia, what angle and orientation are best?……….. Well when mounting solar panels there are two elements of the alignment that affect the final efficiency of the panels.

 

Orientation – the compass direction the panel faces

Ideally in the southern Hemisphere solar panels should be facing as close to true North as possible to reduce the impact that the Winter seasons have on efficiency. Once the angle is above 30 degrees from North the efficiency really starts to drop away.

 

Tilt – the angle from the horizontal

The tilt is the angle that the panels are facing up into the sky. On a flat roof, the tilt is 0°, whereas if the panels were on a wall, it would be 90°.

The best tilt angle for more even efficiency throughout the year is generally the same angle as the degree of latitude of the site. Best for if your only power supply is solar.

Flatter tilt angles increase the power generated during summer, but reduce the winter power generation. If you have a system connected to the grid then you can go 15 degrees flatter than the degree of latitude without losing annual efficiency. (It can even help if your roof doesn’t face directly North)

 

Alignment Efficiency Table

The  table below provides an indication of the approximate solar panel efficiency levels for Melbourne for various alignments.

Orientation

Tilt

15 degrees flatter

Angle of latitude

15 degrees steeper

North

100

100

94

30 from North

98

96

90

60 from North

93

89

82

90 from North

86

79

71

The following site will carry out calculations for sites around the world:

http://pvwatts.nrel.gov/version_5.php

2015 Update

I first wrote this post in 2012 but since then a fair bit has changed.

Off Grid

If you are going to be ‘Off Grid’ its still best to have panels at the optimum alignment.

Grid Connected

If you are still connected to the grid the ‘Feed In Tariffs’ are now that low that there are real advantage in a more westerly alignment.

This means you are generating more power in the late afternoon-evening when you are most likely to be home and using it.

As the cost of panels has gone down it can also be more economical to have a couple of extra panels; rather than pay for angled mounting brackets.

For more Green Ideas see Sustainability

For problems see Reasons For Low Output

 

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