BuildingConsumerismEnergy SystemsPeak OilUrban Projects

A Solar Powered Life – Part I


Photo of the house showing some of the solar panels and solar hot water system

I was happy to read that Zaytuna Farm had installed an off grid solar power system for their electrical requirements — “Advanced Solar, and independence, at PRI’s Zaytuna Farm”. However, upon reading the comments relating to this, I could see that there was quite a lot of misunderstanding and misinformation relating to solar power. This inspired me to write a series of articles covering pretty much all things solar power, what it’s all about and how it works.

My solar power knowledge is comprehensive and growing all the time. This is because I live in the Macedon Ranges in Victoria in a house I built myself which has an off grid solar power system. Having a mild dose of technical geekiness (although this is not necessarily a prerequisite!), I obtained and installed all of the components myself . This system now provides all of the electrical needs of the house. I received no government subsidies or RECs (Renewable Energy Certificates) in the process (because it was cheaper not too) and maintained electrical compliance and Australian standards relating to the power system.

In order to understand a solar power system, you need to understand the term “watt”. Wikipedia defines the term “watt” as one joule per second and that it measures the rate of energy conversion. That’s not a particularly useful definition for easy understanding. In explaining what a watt is, I find that it’s useful to think about light bulbs. We all know what they are, but they each use different amounts of electricity. You may have heard about incandescent 100 watt light bulbs which used to be a bit of a standard in Australia, but fortunately are no longer sold here. You may have also heard about 50 watt halogen down lights, or 15 watt fluorescent light bulbs. The watt rating describes how much electrical energy will be used by this appliance if on for an hour. What it doesn’t tell you is how efficient the appliance is, or, taking the light bulbs as examples, how much light they put out. It is only describing the amount of energy used and nothing else.

References to watts are usually expressed as: number and w. eg. 100w means 100 watts.

Watts can also be expressed in thousands of watts or kW. eg. 1kW is 1,000 watts.

Remember that watts are usually measured over a period of an hour, like a car’s speedometer does for kilometres. Watts are usually expressed as so many watts per hour. eg. 1kW/h is actually measuring 1,000 watts of energy generated or consumed in 1 hour.

Solar power systems come in two forms:

  • Off grid (or standalone); and
  • Grid tied

The off-grid (or standalone) solar power system is like the one installed at Zaytuna Farm in that it literally is not connected to the electricity grid which supplies power to the majority of households. If the electricity grid fails, then Zaytuna Farm will still have electrical power. However, if the people at Zaytuna Farm don’t manage their power usage against their power generation then they will have no power. Off grid solar power systems are generally very expensive because you have to incorporate a facility in your system to store electrical energy (usually batteries) as well as having a place to store the batteries which are quite heavy and a charge controller to ensure that your system doesn’t abuse the batteries.

Grid tied solar power systems are the usual system that you see in urban areas as they are cheaper. The systems are connected to the electricity grid. If for any reason the grid fails, the system automatically shuts down regardless of whether it could feed energy into the electricity grid. The result of this is that the grid connected house will also not have power, even if they are generating solar electricity. The reason for this is that it is possible that the energy generated from the solar power system could potentially electrocute a linesman working on repairing the fault in the grid system. In addition, when the solar power system is not generating any electricity, then electricity is drawn from the grid like any other household.

Either system can be installed anywhere. Having an off grid solar power system is not just for those that live in rural areas. I am unaware of any legislation in Australia that states that a house must be connected to the electricity grid. There is no reason that you could not install an off grid solar power system in a 120 year old terrace house in Fitzroy in Victoria.

I chose to install an off grid system because when I built my own house, I tried make the house have as small a footprint on the environment as possible whilst being as temperate as possible, wanting to make it pleasant and easy to live in. This also meant that I needed to understand about my electricity usage in order to determine if off grid solar was suitable for my needs.

The sad thing is that new houses in Australia are designed and built to be mechanically heated and cooled. They are also sited to face the street which may or may not be appropriate from a solar point of view. Also the materials and the usage of those materials that are favoured by Australian culture reflect ease of construction and form over functionality. This means that from an energy perspective they are expensive to live in, but quick to build and, some may argue, also cheap to build.

In Australia, electricity is predominantly generated using brown and black coal. The electricity generators work by burning the coal to heat water. When the water boils under pressure, steam is produced which then turns a turbine which generates the electricity. What you may also be unaware of is that quite a lot of oil is also used in the process, generally in the mining and transport of the coal.

Burning that coal results in quite a lot of carbon dioxide being emitted. Where I live in Victoria, the coal is known as brown coal due to its higher moisture content. This means that the burning of brown coal is an even less efficient process and generates more carbon dioxide for the electricity produced. It’s not dissimilar from burning wet unseasoned timber as it takes much longer to start burning and it produces less heat whilst burning as energy is consumed in the process of drying the timber out during the actual burning process.

There are a lot of different figures available on the average daily household consumption of electricity in Australia. However, they all seem to be in the range of 15kW/h to 20kW/h per day. For the best case scenario at 15kW/h per day, that’s the equivalent of having 150 x 100w incandescent light bulbs on for 1 hour every day. In comparison, that translates to 1,000 x 15w fluorescent light bulbs. You can see why they stopped the sale of incandescent light bulbs!

On my off grid solar power system I use about 3kW/h per day. Your bill from your electricity supplier will normally tell you how much your average electricity usage is per day in kW/h.

So, what uses up a lot of electricity in a house? A simple rule of thumb is that any appliance that either heats or cools uses a lot electricity. There are some exceptions to this such as plasma televisions which can use as much electricity as a refrigerator.

Examples of items that use electricity to cool are:

  • Refrigerators
  • Deep freezers
  • Air conditioners

Examples of items that use electricity to heat are:

  • Heaters (radiators or fan heaters)
  • Hair dryers or straighteners
  • Irons
  • Incandescent bulbs – these are very inefficient for lighting as they generate a lot of heat as well as light.
  • Halogen down lights – these are also inefficient for lighting as they generate heat as well as light.

Now this doesn’t mean that you should go feral and not use an iron on your clothes — it also depends on how long the appliance is on. You might only use an iron for a few minutes, however, that second fridge in the garage may be using more power than you think as it is on all day, every day. Or, that fan heater that you leave running over night in winter might be the cause of a sudden increase in your electricity bill.

In my next article I will describe how solar power systems work.

As part of the article series, I’m happy to take questions via the comments facility and incorporate the answers into following articles. As a guideline though I will only respond to questions where the products are commercially available and it is feasible for a small scale renewable energy system which can be installed and maintained by someone of reasonable competence. For example: there was a comment relating to the use of solar powered pumping, water tanks and a small hydro generator between two tanks. I would respond to this as it is certainly possible. However, if you are asking me about capturing solar thermal energy and storing it in molten salt to be able to generate power at a later date through a steam turbine, I’d have to say that this is only applicable to large scale systems and beyond the average installer.

As for feeding garbage to a Mr Fusion generator attached to a DeLorean motor vehicle so that you can power a flux capacitor so that you can travel back in time, forget it!

Click here to continue to Part II.

21 Comments

  1. Nice article.. look forward to more information to better understand the topic. So, when a local solar power installer is advertising a 1.5kW solar PV system (Grid tied) would you expect the 1.5kW to refer to be peak output, a per hour, per year etc? I went to their website and there is not really much more information, however their ‘savings’ calculator suggests that a 1.5kW system would save about $650.00 Per Year. Would you have any guess at what the 1.5kW actually means?

  2. Hi thankyou for the informative response to your first posting. I am on the grid and about to have free panels put on my roof through Sanctuary. It involves a 5yr contract with free panels/installation and they receive a proportion of the profits.
    I enjoy reading your post because it was a difficult decision as I hoped to be independent of the grid. But the offer was incredible as the costs are beyond me.
    What I would ask if you can supply information on the best solution on how to provide solar hot water that I can make my self and serves a family of 5 in part shady environment.
    Thank you for your time. jO Hoy

  3. Great article Chris.
    My question for you is can an existing grid tied solar power system be converted into an off-grid system? Specifically, is converting just a matter of setting up the missing components (i.e batteries, storage place for batteries, etc) ?

    Really looking forward to the next installment.

  4. Hi Chris, thanks for the article.

    I know some others mentioned it but perhaps you ought to clarify this more fully in your next article. For a house sized load its best to talk about kWh as the unit, as in, 1kWh is 1kW used for one hour.

    This is 3,600,000W in total (sorry Chris, never a small w). This is because the Watt is a per second measure so 1kWh is 1000W EVERY second over 1 hour, 1000W x 3,600 seconds. On the other hand kW/h is a change of rate (hence the / or “per unit”). This is fairly basic high school physics and maths but important that people talk about things in the same way as the equipment will be specified. Go check it out if you think JBob and I are wrong its always good to use the right units when talking about this stuff which is what your article has set out to do. :)

    People also should realise that the Watt is a pretty small unit of power (1W = 1J/s and the joule ain’t big).

  5. Wow! You built that yourself? Great job! I struggle to really understand solar, so I’m looking forward to this series of explanations! Thanks for mentioning it on ArchDruid Report.

  6. D’onya, with electricity bills of average Victorians set to reach $2,000 a year and more things like this will be looked at more closely as time goes on.

    I only have electricity as the only utility on the farm, useful for welding, and the stove/oven, lighting and refrigeration.

    If I can sort out a way to take care of all of the above (rocket powered stove / oven?, a couple shipping containers buried underground as cool food store rooms and perhaps cheese maturation rooms, small solar only for on-farm lighting, solution for electric welder on 3-phase?) then then I would love to kill the electricity service but will still have small fossil fuel inputs in tractor fuel and welding gas?….

    The only thing I missed in having moved from NSW is they had (still have?) the best rebate scheme in Australia for grid-connected solar. Victoria can not even come close.

  7. Hi all,

    Thanks for the lovely feedback and comments. Part 2 of this article is now being written and I’ll respond to your comments and questions there.

    Regards.

  8. Responses to questions and comments from A Solar Powered Life – Part 1

    • Anji – Thank you

    • Jbob – Thanks. I have corrected from Kwh to kWh

    • Alfcon – Thanks and see Jbob response

    • Mikey – Excellent question. I’ve started covering this question partly above, but it should be completely covered at the end of the Part 3 which will look at how solar panels operate in the real world

    • Tony – Thank you. Most people are unaware that in Australia, legally anyone can install an off grid solar power system not exceeding 48 volts DC. I’ll cover this issue in a later article.

    • Zainill – Thank you

    • Jo – Free is good! Given that you live in a part shady environment. You may be interested in the next article which will cover how solar panels operate in the real world

    • Alexia – Thank you

    • Paul – Thanks. The answer is yes, but the existing grid tie inverter cannot be utilised in an off grid system and the solar panel array may need to be slightly rewired which I’ll cover in a later article. You could always sell the grid tie inverter though to cover some costs.

    • Peter W – Thanks. I’m neither a physicist nor an electrical engineer so please be aware that I won’t enter into these sorts of discussions in future. Wikipedia states that “A kilowatt-hour is the amount of energy equivalent to a steady power of 1 kilowatt running for 1 hour, or 3.6 MJ” and you’ll find this quote with the link for reference 1 in part 2.

    • Cathy – Thank you Yes, except for a few areas such as the mains 240 volt wiring and plumbing, it’s all my own work (all 60,000 nails so far!), I even built the frames on site. There were some scary moments, but it’s gone pretty well really. I’m hanging to get some time to get back into the orchard though.

    • Peter – Thanks. I am aware of a person in NSW who has a pretty similar off grid set-up to mine and he runs a welder (not 3 phase though), so you can certainly have an off grid system where you can run a welder as well as everything else in a household. If you’re interested in knowing anything more about the welder brand and model, leave a comment and I’ll track down the information.

  9. I see here the Australian government page contains the failed green clean initiative of windmill farms on its front page image.
    https://www.livinggreener.gov.au/energy/power-prices
    However, if you thought that was bad, i recently priced putting practical levels of solar onto a standard house remembering that with the past 30 years development of white-goods for energy efficiency we find those now cost too much. The shock i found is that too actually “off grid” the house at the minimum 5Kw with batteries would for a single system no spare parts, be the same akin to paying of a house and its loan over 10 years. It would cost 10 years of electricity bills with very low ensurance of the devices remaining servicable for 10 years at least of battereis are half of the minimum $14,000 cost DIY for most of it. Worse, at around the same price with “grid tied” inverter system it remains as endangered and unsecure in its environment but is the minimum to halve the electricity bill , and has been chosen by me as the most suitable for a set of relatives(by Kw size) and most households(grid tied) as most are not in a RAPS grey area for remote living as my relatives are.
    What commonly isn’t understood by governments is that price tag and viability of system install. There are only 3 hours in any day part morning and part afternoon in summer when the temperature is below and also around 25 degrees Celsius so the solar panel cells are operating at maximum efficiency. As this previous technical statement suggests there is a lot to simply actually know about using solar so “grid tied” is the closest to “set and forget” because most people will never be an amateur or technician to the technology “that is a pre requirement to self sufficiency ‘off grid’ “. This means any saving a normal household requires in a house with 1 freezer,1 fridge, 1 hot water system and 1 dishwasher, MUST use at least a 5Kw “grid tied” or they are wasting the point of it all, However, it isn’t them that’s wasting it, its the government not seeing the point of only subsidising 5Kw “grid tied” and to a lesser “off grid 5kw or more” for everyone and no other size until there becomes special needs to apply for alike RAPS.
    Just the same as the wind-mill generator FAIL on the green living front page, they have failed to see the cost of components and the bare minimum to bother with economically (3kw may be the minimum to install to a flat unit – but for size and space How?).

  10. Hi Nicephotog,

    Err, the website that you refer to is actually telling people to switch off appliances at the wall. It highlights government estimates of 10% of all household electricity consumption in Australia being for appliances on standby. What standby means is that an appliance is switched on but performing no useful task.

    For example if you have a television switched on at the wall socket, waiting to be switched on via the remote control, that television is using power. The website is pointing out that you are paying for this power consumption. Turning the appliance off seems like common sense advice.

    Unfortunately, the remainder of your comment makes very little sense. Can you please revisit your comment to make it a bit easier for readers to understand? As a general note, it is often a good idea to re-read your comments prior to submitting them.

    I’m happy to discuss these issues after you have done this.

    Regards

    Chris

  11. An interesting article, my background is Mathematics/Physics and then EE so I have a rough idea what I am talking about. I am all for solar and am planning to do something similar, it makes sense in a country where you almost need welding goggles to go out in the sun at midday. The issue I do have with all of this though is how poorly basic science is understood, not only by the public at large but the regulators have even less of an idea.

    To give one example in Australia there is religious preaching about the evils of incandescent bulbs and how clever everyone is for “banning” them. Of course they generate “waste” heat, but for the majority of the population here that heat isn’t really wasted for six months of the year since to raise a room to the same temperature the little fan and bar heaters everyone uses here have to work harder. It is year 11 physics.

    I have no idea what the savings and losses would be, it would be easy to guesstimate for a bored person. The point still remains though that it is easy to jump on band wagons without understanding where the wagon is even heading – in this case to a toxic landfill with minimal real energy savings. (I accept that wood heating being carbon neutral would circumvent the issue – but Australia is the most suburban population on the planet.)

    I was also pleased to see the mention of the 49.99999V reg which is one minor part of the regulatory nightmare for anyone thinking outside of the brick veneer/tin roof box.

    I could go on ranting but I will spare everyone the pain. Thanks again for an interesting read.

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Articles

Back to top button