Solar panels/ Solar power

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All you need to do is look at your last electricity bill it will show you how much energy you use per day/month in the form of kWh.

Type the number in here http://www.energymatters.com.au/climate-data/grid-electricity-usage.php


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Profit

 

The maximum power you can draw from a power point is 2.4kW (10A at 240V). There are several household appliances that draw close to that maximum (tumble drier/dishwasher/hair dryer/kettle/oven/AC). The worst of these is the tumble dryer because it runs at full power for an hour or so, the others run at full power for minutes typically (AC usually runs at full power for a few minutes every so often).

All other appliances in the house are pretty much noise compared to these big loads (40 downlights = 2kW).

In terms of how useful that 2.2kW is - well its useless for light globes for starters

 

theres a difference between going totally solar powered, ie "off grid" and using a grid connect offset system.
to go off grid is doable but difficult, requiring battery banks, low voltage appliances, rewiring the house for 12v etc etc
the vast majority of residential systems are grid connect, meaning power generated in daylight hours is fed to the grid, effectively running the meter backwards to offset power usage over the 24 hour period.
the thing that makes it all work is the government mandated feed in tarriff which is around 50c a kwh in SA. (arguably an inefficient and wasteful use of resources vs investment in nuclear power but thats another debate!)
the average house uses 20kwh per day.
the rule of thumb is that you will generate 4.5 kwh per day, per kw of installed solar capacity - so a 2.2kw system will on average generate 9.9kwh per day.
it is possible to live off this, my parents have been running on a 2kw system for 5 years and have never paid a power bill, in fact their account is currently around $1500 in credit. this involved significant lifestyle adjustment though, and incorporated super efficient appliances, no air conditioning - wood heating, and a specially designed house.

 

Yes petrol is cheap... but not as cheap as coal

Petrol = 34 MJ/l = 3.5c/MJ or 28MJ/$ (at $1.20/l)
Coal = 24 MJ/kg = 0.3c/MJ or 300MJ/$ (at $80/tonne for Newcastle thermal coal).

This is why we use coal to generate electricity

Even I could make my house revenue neutral with that feed in tarriff!

 

Put a young boy on an exercise bike in the back yard, have'nt you seen the XXXX ad.

 

Mate i wish, my house uses 32kwh per day and im never even home. thats just the pool, hot water, and TV when i actually am home.

i looked into it and i need a 4+kw system to make it neutral for me ($ wise) and thats a $16k install. vs the 8 years of electricity it buys me.

 

Thats ok. Especially if you are going to live there for the rest of your life.

$16K is **** all.

 

You do have an average Australian house - the Australian average is ~1.5kW average which is 30kWhr/day. 20kWhr per day is 0.83kW average which is more like Europe. The US is 2.5kW and Japan is ~0.75kW average consumption.

An 8yr payback is pretty good - but if reliant on Government incentives that is a bit of a worry!

 

yeah, but that 8 years isnt accounting for the ROI on that $16k should i put it elsewhere, its also dependant on the buyback price being 2.5 times the actual tarrif rate (not likely to stay that high much longer).

and what happens if the panels get destroyed in one of our famous hail storms. i know insurance covers them currently, but i bet once a few claims get made for solar panels damaged in storms, the insurance companies will not cover them, or impose additional insurance on them.

and then the other thing in my mind (and this is purely speculting based on things ive heard, im sure you can provide more input as you work in this field), dont Solar panels reduce efficiency over time? and most only seemed to have a 5 or 10 year guarantee efficiency. so is it likely that they will not be producing much energy at all after that time? is it an exponential decay curve?

 

I just heard on the radio here before that the Gov is buying it back at 5 times the rate till 2012.

I dont know if the radio here is right or you are?

Ive never heard of solar panels losing their effienciency before.

I know they are not *that* efficient in the first place.

 

current tarrif is about $0.19 per kwh, but the buy back rate is $0.50 per kwh. so 2.5 times, but i bet they're probably quoting some lower tarrif (like an off peak tarrif etc) of $0.11 per kwh or so.

i dont know if they actually do loose efficiency or not, but i did notice while looking into it in real depth last year, they only warranted the panels for a % efficiency over time. which to me implies that they loose efficiency over time. I am not sure of the ins & outs, which is why i posed it as a question.

but even then $16k invested, at even a conservative ROI of $6% is $1000 per year it needs to recover for you to be worthwhile,

in turn even on a very basic NPV calculation it will then realistically be 11 years to repay itself (assuming CPI for buyback & tarrifs).

all quite basic calculations, and the reality is electricity is going to increase far more than CPI. but still 11 years to recover the investment is not really worthwhile IMO.

 

9% per annum is excellent. ROI thereafter is gravy.

 

I think they do reduce over time - but they should still exceed 80% or so of rated capacity after 30 years of cost free running and still be going.

 

Gordon Gecko is after robber baron profits

 

Cool man.

IF I was going to live in this house for the rest of my life, id invest the $16K or whatever it took to do it.

But im not, so I will happily pay $2500 or so a year (today's rates) for electricity.

Only going to get more expensive with kids running around and the Gov jacking the rates up, but whadda ya do.

 

did you see the new inventors last night, a professor and his group of students are developing a polymer solar cell that can be produced very cheaply and can be applied to the whole of your roof. It is 1/2 as efficient as a solar panel but you can cover your whole roof so it makes about 4 times the usual kw. They say that it will be perfected in about 2 years and will mean that you will be able to produce enough power for a normal household for the cost of about $3000. They are also working on a conductive paint so you can place it on a special coating on your house and produce electricity.
The day it comes down to $5000 and you can store and equate to your normal use is the day I change and goodbuy energex,agl etc. then all we need to do is produce our own water, do our own sewage processing and stuff the city council robbers.

 

Didnt watch that show, but that does sound impressive!

 

solar is the way to go, my brother in law is a sparky and raves on about it. dont understand everything he says as i am a fruiterer not a engineer, but he buys his panels from www.rockby.com.au have a look, he says they are very reasonably priced

 

A friend has just had a 2kW array installed which cost $4k (after rebates etc) - seems a pretty reasonable deal in WA where power bills are ~$400/m.