My Roof-top Solar Power Installation

We have a small photovoltaic (PV) solar power system installed on our rooftop in Narooma, NSW, Australia. The installation and connection to the NSW electricity grid was completed in January 2010. That same month the NSW government introduced a gross feed-in scheme in which energy generated by private rooftop solar systems were credited at a rate of $0.60/kWh – the scheme period is seven years.

Our solar power system has now been operating for over six years and some details of the power generated are presented below.

 

SOME DETAILS OF OUR INSTALLATION

Located in Bluewater Drive, Narooma, NSW.

Roof slope 19°

Aspect 73º (approximately ENE)

1 kW power capacity (6 solar panels)

 

Solar_1A

Roof-top installation (looking south)

 

Solar_2A

Indoor switchboard (inside garage)

 

SUMMARY OF SOLAR POWER PRODUCTION

Plots of the monthly energy production over the six year period, February 2010 to January 2016, shows the marked seasonal variation.

In peak summer months (December/January/February) the average daily energy production is 4.7 kWh. However, this can vary from about 7 kWh on sunny days to about 1kWh on cloudy days.

Average daily energy production in peak winter months (June/July) is 1.8 kWh, but this can vary from about 2.5 kWh on sunny days to almost zero on cloudy days.

The average annual energy production (over the six years, Feb 2010 to Jan 2016) was 1,292 kWh. At the NSW gross feed-in tariff rate of $0.60/kWh this resulted in an average annual credit to us of $775.

The average daily period of generation varied from about 13 hours in summer to about 9 hours in winter. Over the six years, the average annual hours of power generation was 4,100 hours.

The following plots of our solar power generation illustrate the variation in solar outputs:

AVERAGE DAILY ENERGY GENERATION (February 2010 – January 2016)

Solar KWH

 

AVERAGE DAILY HOURS OF GENERATION (February 2010 – January 2016)

Solar Hours

 

SUNNY SUMMER DAY GENERATION (19-20 January 2010)

Solar Summer

 

SUNNY WINTER DAY GENERATION (14 July 2010)

Solar Winter

 

COMMENTS:

My 1kW solar power generation system cost me a total of $2,387 in 2009/2010 (this includes all installation costs and after government rebates). Maintenance costs, so far, have been zero. The NSW gross feed-in tariff introduced in January 2010 was a generous $0.60/kWh and this tariff still applies for installations made at that time. Based on energy production in the past six years, my installation cost repaid in credits within a period of 3.1 years – a rather attractive investment from my personal viewpoint.

I am well aware of the criticisms of generous feed-in tariffs paid by various governments in order to promote their “green” image. These generous feed-in tariffs are in fact paid for by other power users and/or by government subsidies. The NSW government is also aware of this and has recently reduced the gross feed-in tariff to $0.20/kWh. On the other hand, the cost of rooftop solar installations has also decreased since 2009 and many people still consider such installations to be sound investments from both economic and environmental viewpoints.

The primary purpose of my solar power installation was to quantify the amount and variation in power that could be generated on my rooftop. I was mainly interested in the physical processes involved and any economic benefit (to me, if not to the State or the country) was a bonus. I have not investigated the overall economic and environmental benefits of such rooftop solar installations but some commentators consider that these may be minimal or even negative. However I have managed to draw some interesting (I think) graphs and have improved my understanding of the solar power generation process. I hope that this may be of some interest to you also.

 

Brian Gunter

brigun@westnet.com.au

 

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