Newsletter Archive

E-News Issue #29

7 March 2000

TV Power Consumption

One of our customers, Chris, has reported that his 68cm Daewoo TV with teletext only draws 75W.

Bread-makers

For our longer article this month, you can read about my bread making activities!

HOW I BAKED MY FIRST LOAF OF BREAD

I recently upgraded my own solar system, thanks in large part to the new Australian Greenhouse Office 75% rebate, so I decided to purchase a bread maker.
For those of you not familiar with this product, I'll briefly describe what it does.

In simplistic terms, it bakes your bread with about 30 seconds of work - just measure your flour, water, yeast, salt and any other goodies you want to put in your bread. Select the loaf size, crust colour, flour type and the time you want your loaf to be baked by and the machine does the rest! Over the next 2 - 3 hours, the unit goes through several cycles: two types of kneading, a rise, first punch down, second rise, shape, third rise, bake and an optional keep warm cycle.

I did some research first. I had a look at a Choice magazine article (published by the Australian Consumers Association). They tested 11 models and reported that all but one baked an excellent loaf of bread. They calculated the cost (with grid electricity) at less than half that for a store purchased loaf.

The article suggested that one look for the following features: adjustable loaf size, removable pan and lid for easy cleaning, timer, keep warm function, crust colour selection, capability to make jam, pasta and pizza dough, fruit/herb dispenser.

We asked the author how much power they used and she reported that they used between 250 Whrs and 650 Whrs with an average of 330 Whrs per kilo loaf. However, the Choice article didn't tell me how they'd run on my SE12 Selectronic Sine Wave inverter (7000W continuous rating).

I remembered some of our customers had given us some good feedback in this regard so I consulted the archived editions of the Rainbow Power Company's free email newsletter. Someone had earlier warned us that the Panasonic SD250 had problems even on a sine wave inverter.

In the December 99 newsletter, Stephen Hart had reported:
"I currently have a Breville BB400 bread maker. It works perfectly on both my previous modified square wave inverter (Selectronic Silver Series 600) and my new sine wave inverter (SEA Boxer 1500). On the SS600 it was slightly noisy, as you would expect from any induction motor.

On the sine wave it performs just like on the mains. This is a fairly expensive machine ($279 at Target stores) but has more features than any other machine, including 30 minute power failure memory protection. It also has the lowest power consumption at only 425W.

My only complaint of this machine is that it is quite noisy when kneading. The pan fits fairly loosely in the machine, and the kneading paddle fits loosely on the shaft, so it tends to rattle and clang a bit. I went through several other machines before getting this unit. (Thanks to Myers stores for their flexible returns policy). Details as follows -

Sunbeam BM100: not tried on inverter. During the heating cycles the 600W element is switched on and off several times per second as the chamber approaches the cut off temperature. You can hear the relay "fluttering" inside. My understanding is this is no way to treat a relay, and I doubt an inverter would appreciate it.

I phoned the service department who said to return it to their service agent, they thought it didn't sound right, but when I took it to the service department, they said it was normal. I got two more under warranty but they did the same.
Returned for refund...

Breville BB350: Worked OK on modified square wave inverter (SS600) though quite noisy, more so than the BB400. This model proved quite unreliable. I had three replacements under warranty, they all died mid-cycle after a couple of weeks each (on the mains, not on inverter).

My sister had one of these too, which lasted about four months, the warranty replacement has lasted three months so far...

Panasonic SD250: This machine was streets ahead on quality. It was quiet but was completely useless on the modified square wave inverter. It wouldn't even start ... as soon as it was plugged in you could hear a relay clicking on and off about once a second. No other signs of life.
I didn't own the sine wave inverter at the time so didn't try it on that."

Armed with this information, I visited my local appliance store. The prices ranged between AUD$99 and $279. The wattage on the compliance plate ranged between 450 and 700W.

I found the Breville BB400 recommended by Stephen. Unfortunately it was the most expensive one at AUD$279. However, it had all the features recommended by Choice magazine and I knew it would work successfully off my inverter.

The price included 6kg of flour and a colour book with about 100 bread recipes to tantalise me. So I lashed out and bought it, got home and a few minutes later I was baking my first 500g loaf of bread! At a battery voltage of 25.0V the bread maker drew about 100W while kneading. While baking, it drew a maximum of 480W, however this cycled on and off every few minutes.

The power used for a 500g loaf was 210Wh (about 10Wh for kneading and 200Wh for baking). A one kilo loaf would use about 265Wh (all measurements taken on the DC side of the inverter using the Plasmatronic PL40 regulator with shunt).

The economics of the exercise are impressive. The unit is obviously very efficient. However, having designed and sold solar PV systems for some 15 years, my general advice has been that solar PV is not cost effective for cooking and heating.

Times are changing! Appliances are becoming more efficient and the cost of solar modules is coming down (especially if one considers the AGO rebate of about 75% on RPC prices for solar modules).

If I baked a loaf a day, I'd save about $400 per year compared with store bought bread (not to mention the convenience and taste sensation of home baked bread).

Assuming one lived in a reasonably sunny location and baked during the day, an 80W solar module should be able to provide the power.

At a cost of about AUD$600 for an 80W solar module ($150 after the AGO rebate) I think my accountant would suggest that I made a wise decision (even if one was to consider the cost of the bread maker and arguably a larger battery than might be needed!)

Oh, and before I forget, the bread was wonderful!

Cheers from Dave and all the RPC crew.

Dave Lambert (Director)

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We install solar systems in Northern NSW and Southern QLD.


QLD:
Gold Coast (from Coolangatta to Southport), Nerang and Hinterland (Beaudesert) and out West (Warwick, Stanthorpe, Killarney)


NSW:
Northern NSW (Tweed Heads to Yamba, including Evans Head, Byron Bay and Ballina); the Far North Coast Hinterland (Grafton via Lismore to Murwillumbah) and out West (Casino to Tenterfield, including Drake and Tabulam, as well as Woodenbong and Bonalbo)

For larger system we also go up to Brisbane or down to Coffs Harbour and even Glen Innes. Other places by arrangement.