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Rainbow Power Company Enewsletter #104
- 8 February 2007
Index:
1) Introduction:-
Welcome back from the Christmas break and the start of an exciting year - our 20th year of operation!
I feel it will be exciting as the world finally comes to accept the problems and challenges of global warming.
For our industry, grid connected systems are becoming more prevalent. From July 1 we should have the AGO solar rebate extended with perhaps increased levels of assistance.
This will be a bumper issue of the enewsletter so I better get on with it hey!
2) New Online Web Shop:- We are pleased to announce a brand new look web site. All the information that was on the old site is still here of course - an estimated 3000 pages or more! We believe that generally it will be easier and quicker to navigate. The exact URL of each page will now be displayed onto your computer (unlike the former site with `frames´)
In the Web Shop section you will notice quite a few changes. Most of the 600 products have nice new pics thanks to Dave Christmas. The same product codes have been kept but some of the products are in a new section - eg the Sundaya kit lights are now in the lighting section. We feel the new `cascade type menu´ on the left should make product identification easier and quicker.
The web Shop has an on board `Quick Find´ search engine. If you want, for example, to see all the Sundaya products together, type `SUN´ into the search facility. Those of you who already had `complete´ details in our computer as a previous customer should have received an email last week inviting you to let us migrate these details to the shop. This means you won´t have to type in your name address etc etc to make a purchase. (Note - we do not store/retain your credit card details). Last but not least, we have placed some of our panels on special - so check it all out when you have a few minutes! http://www.rpc.com.au
3) Pumps:-
As a number of customers have experienced problems with the variable speed Shurflo pump, we have decided to discontinue this model. However, the smaller standard model has not been a problem and we have put this model on special. We are now carrying a range of Johnson pumps for the domestic pressure pump application. With a 3 year manufacturers warranty we feel they will prove to be a lot more reliable than the other brands!
4) Efficiency of 12/24V and 240V
Pumps Hugh Murtagh contributed the following article before he left us to undertake an electrical engineering degree:-
To test the efficiency of a pump, its application first needs to be determined so we may emulate daily use. In an energy efficient house, it could be that 1 shower and 1 kitchen/laundry tap are running at the same time for perhaps 1 hour per day. Two types of pump were tested and found to have positive and negative aspects: A 12/24v variable-speed pump is capable of running the above requirements at reasonable pressure. However, the 12/24v pump is not capable of doing more, and diaphragm replacement every 2 years can be discouraging.
Variable speed 12/24v pumps negate the requirement for a pressure tank and allow soft starting and half-power running when the flow is low. A 240v pump (a DAB 750w centrifugal) certainly can produce more flow, and will also allow the user more pressure for hoses and other uses. The 240v pumps, however, do not have variable speed controllers on the small scale (household pressure) models, but are instead fitted with a flow sensor switch that ensures the pump continuously runs even if flow is very low.
This means that the backpressure on the pump during low flow operation is extremely high, and the pressure build-up is only curtailed by the natural slip characteristics of centrifugal pumps. This is not an efficient method of flow smoothing, and the old style pressure switch/pressure tank combination results in a more efficient, reliable, and cost effective pump. NB: The test of the 240v pump demonstrated that the pump actually drew less power than stated (approximately 620w) at a backpressure typical of a showerhead.
The resulting current flow at 12/24v nominal was 70 amps including inverter losses (Selectronic WM1400). The battery voltage was actually an average of 11.9 under load meaning the total power consumption was about 830w. The low voltage pump (a variable speed pump, typical of all larger model 12/24v pumps) drew only 80w at a similar voltage.
Over a period of 1 hour, each pump was run to establish how much water could be moved in that period of time and how much power is required. The results showed that the 240v pump would move twice the quantity of water in one hour compared with the 12/24v pump, but took over ten times the power.
This fact, in combination with the surge requirements for stop-start operation, makes the 240v pump unsuitable for all but the largest power systems. Even if the 240v pump was half the wattage (there are some 300w models available), the efficiency would still be too low to compete with the power efficiency of 12/24v models.
5) Edison Screw Lampholder:-
As many of you are aware, we are stocking many more 12 & 24V in the ES17 base. These are the reliable Sundaya brand and we feel they are a safer in that they can´t be inserted into a conventional 240V ES27 lampholder. However, for those of you who have already installed conventional ES lampholders, we now have an adaptor (LYF-001). This will also allow you to easily convert desk lamps etc to take a Sundaya fluoro or LED light.
6) Energy Payback for Solar:- We still hear the myth that the energy to manufacture a solar panel will never be produced by it. We are pleased to reprint a review of the scientific literature in this regard from the Environmental Engineer.
Dave Lambert and the RPC Crew
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