Solar to Grid Micro-generator in Sydney, Australia

Energy use measurement and the resultant awareness brings the added stimulus to reduce consumption. I wonder if perhaps the most energy impacting factor in a solar installation is not the 'alternative' production but rather the consumption reductions, the conscious lifestyle changes that come from being informed (managing with measurement). On a cold rainy wash day I groan inwardly, but then shrug my shoulders knowing I'm looking down the barrel of a 30-40KWh day until I choose to change the way I dry clothes and/or reduce the house heat settings and/or dress more warmly for indoors.

More promotion of Alternative energy supplied by grid. The power I buy from my supplier is 50% renewable. The provider is under obligation to source at least the agreed renewable proportion from wind or solar. This energy is provided at the market base rate, currently 17.62 cents per unit.

I can buy 25% renewable at no extra cost above the standard unit price. This was my entry to buying green power for the first six months of my Solar implementation. I think this should be mandatory for all consumers. I can nominate to increase that proportion of renewable energy from my supplier by adding 2.75 cents per unit for a 50% proportion or 5.5 cents per unit for 100%. This was my next area of investment before I looked at expanding my physical solar plant. Replicating this approach throughout the market would continue to place downward pressure on energy consumption, regardless of the source while reducing Coal generation dependancy. I'm looking forward to the prospect of purchasing 100% renewable grid power AND pumping back my solar production at a good by-back rate. Bring on Gross Tariff buy-back in NSW, or even better, have a National approach to alternative energy buy-back. Sign a partition here - http://www.feedintariff.com.au/

Aim
- to keep grid consumption at or below double of solar production. This will create a neutral or better net non-renewable power consumption impact.
How
- purchase 50% renewable energy from Grid at extra 2.75c/kWh
- added electric boosted (hopefully not) solar hot water, switch off electric booster (this changes with visitors or colder weather). Set HW thermostat to 50 degrees. Water conserving shower reduces energy required to re-heat replacement shower water. Washing machine uses cold wash cycles where possible. Avoid washing on rainy days to minimize dryer usage. Use economy or fast wash cycle on dishwasher.
- turn off at the power point any non-essential devices (exceptions - refrigeration, network/comms/UPS equipment) I use IR power boards that manage several appliances using remote control.
- minimize use of heating devices (ironing, heating/cooling, cooking)
- replace all lights with energy efficient globes
Yet to do
- Add more panels (subject to Tariff discussions currently in play)

2/7/2009 Rheem 340lt Solar Hot Water split system with 2 collector panels replaces 125lt 3600kW electric tank. This should be a celebration BUT the manufacturer designed placement of the reticulation pump cold thermistor sensor is wrong!

I heated 200lt of water using 3.6kW booster element to 55 degrees using ~7KWh of grid electricity. Next morning I watched the outlet temperature drop from 50 degrees at 6am to 20 degrees at 10am as the reticulation pump responds to 7 degrees variance from the cold outlet at the bottom of the storage tank to the hot outlet at the top of the panels. By 3pm the hot water outlet temperature climbs gradually back to 30 degrees, maximum ambient temperature 14 degrees C, on a clear winter day.

So, what the manufacturer suggests should happen is I leave my electric element switched on so the cool water being pumped off my roof panels at around 10 degrees C into my 50 degree hot water tank cools the tank contents until the electric thermostat cuts in and REHEATS the water I heated with electricity yesterday which has now been cooled by the inflow from the solar panels. This occurs before there is enough heat from the sun on the panels to effectively heat water delivery to the house, ie less than 40 degrees C. The result is a 10kW increase in daily energy consumption instead of a 10 kW decrease (solar only hot water). This is Solar boosted Electric Hot Water!

The bottom line;
This (and other units like it) are designed to heat the top 200 litres of water in the storage tank with the electric element as it is used in the house and cold water from the mains supply replaces the volume used. During the middle of the day the solar panels boost the temperature of the bottom 140 litres of water in the tank to reduce the temperature differential for electric heating when hot water is used (usually outside solar heating hours).

Update 10/7/09 Rheem technical staff do a site visit. I was given an extra temperature sensor, fittings and technical advice on its installation on the house outlet at the top of the hot water tank instead of the cold solar outlet as the bottom (as designed).

Using the above modification I manually override Rheem's design so the solar heated water being pumped into my tank from the panels is always hotter than the water stored at the top of the tank, optimizing solar only operation. Even on winter days, there is enough heat captured to raise the temperature of the full 340 litre tank. I only boost the tank electricly at the end of the day if the outlet temperature is below 45 degrees Celsius. Apart for July, the coldest month of the year, little or no 'boosting' is required. Now I save around 10 KWh of electricity per day from the system I replaced!

Update 1/9/09 Hotwater has been completely Solar for the last 3 weeks without any electrical boosting. Tank outlet temperature ranges from 50-70 degrees C. Daily power consumption is 30% less than before the solar hotwater installation in June!

SolarNetwork.net connects to my PV system. Data displays as SolarNode19 here
SMA Sunny Boy 1100 rs232 coms into a linux microcomputer wirelessly transmits live data to a java server opensource environmment. More SolarNetwork.net information here

Installed 2 power inductance meters on the grid and Solar feeds to my house.
Specs here . Still exploring how to capture the radio signal and include in data tracking via the linux microcomputer.
Aldi are selling them at $79 while stocks last!

26/09/2009 - 2mWh of PV production since go-live, June 2008.
11/01/2010 - 2 tonnes of CO2 reduction since go-live, June 2008.

January 2010 Best PV return on investment $109.16 @ 66c/unit for 165kWh

7/5/2010 - 3mWh of PV production in just under two years since initial installation.

3/1/2011 - 4mWh of PV production since 1/5/2008

01/07/2011 - 17% increases in Grid prices. Reduced Renewable option from 100% to 25%. Unit price dropped from 25cents to 18cents. (about $380 per annum)

Enjoying PVOutput.org where there has been great work done for providing a useful comparative PV production and Grid consumption charting environment. My live data

6MWh PV production in just under four years.
Now to further reduce consumption;
- Gas kitchen and gas/solar hot hotwater conversion.
- Improve solar thermal conservation in living space by increasing north facing window exposure.