Gas HWS or Heat Pump HWS

[Mr Brush]

Our experience with Sanden mirrors what you describe - it draws around 900W, and is virtually silent even standing right next to it. Sanden tanks are stainless, although we have the tank under cover in the garage (a purpose-designed nook where the old Quantum HWS used to live). The compressor unit lives outdoors in a services area on the other side of the wall from the tank. The Sanden unit is MUCH quieter than our old Quantum heat pump HWS, which used to sound like a very noisy refrigerator when running.

I haven't bothered yet, but it is possible via the display panel on the side of the Sanden to set up times that the unit is allowed to run - you have to remove the metal cover to get at the control panel. Since we're running 5kW of solar I had planned to set the Sanden up to only run during sun hours, but with an overall house power bill for the last quarter of $65 (including some use of aircon) it hardly seems worth it.

[Optimark]

I would assume the Sanden stainless steel tank should last as long as an Aquamax stainless steel tank; the Sanden tanks are made by Aquamax in Moorabbin. My brother works there.

Thanks for that, I've read the instructions for taking the lid off to set the compressor running times, but at the moment I'm monitoring when it comes on and for how long before I do set anything.

We have 7.7kWh of panels and at this time of the year we are running 24 hours a day from solar and batteries. In fact just had a quick look and over the last 365 days, the rooftop solar combined with the batteries provided 85% of total power consumption.

With two less people in the house this coming winter, along with the possibility of us having a holiday in winter, I would think we may even get to 90% of annual electricity consumption from the roof solar and batteries.

This electrical consumption figure is even more astounding as we have been running reverse cycle air conditioners to heat and cool the house since the middle of last year. We haven't pulled out our two gas wall furnaces, but we may next year. Then the only gas consumption will be the cooktop, if we replace that with an electrical unit of some type, then we'll remove the gas altogether and thereby eliminate another fixed daily charge.

Mick.

[yvan]

Welcome to the Sanden club Optimark!!!

We use a gas-fuelled instant HWS to supply our kitchen sink only, and the cost is 3.5x that of running the Sanden for the same period....
Mind you, the electricity company charges a daily supply fee which ends up being higher than the actual electricity charge...

We are now thinking about installing batteries. I'm not sure that it would get amortised quickly but the cost of energy is likely to increase over time, even as electricity costs are now becoming a political issue!!!

Cheers,
Yvan

[Optimark]

We are now thinking about installing batteries. I'm not sure that it would get amortised quickly but the cost of energy is likely to increase over time, even as electricity costs are now becoming a political issue!!!

Cheers,
Yvan

Yvan, this could be of interest to you.

EV chargers for V2G and V2H to arrive in Australia within weeks, after long delays - ABC News

We've had house batteries for 2¼ years, they are a bit different to the normal dry batteries as they are flow batteries, but although the payback, which is important to some people but not to us, is rather long or non existent. The possibility of using an automobile battery for house consumption and storage may change some peoples mind.

Mick.

[Mr Brush]

V2G and V2H will be a game changer, but it will be a couple of years before most brands of EV are compatible with the technology.

Already being deployed elsewhere, but as always Australia is way behind the curve.....

Why have a dedicated 8-10kWh home solar battery when there is (likely) ~50-60kWh battery capacity sitting in your car? Rather a conflict of interest for Tesla; if people can use their car batteries for storage will it cannibalise their home solar battery business?

Optimark - I presume you have the Redflow battery, which coincidentally I was reading up on earlier today (curious to see where the technology had ended up). There still seem to be a few questions surrounding charge/discharge cycles, warranty, etc., but one big appeal is obviously safety (vs. lithium ion, etc.). How have you found it?

Cheers

[Optimark]

Optimark - I presume you have the Redflow battery, which coincidentally I was reading up on earlier today (curious to see where the technology had ended up). There still seem to be a few questions surrounding charge/discharge cycles, warranty, etc., but one big appeal is obviously safety (vs. lithium ion, etc.). How have you found it?

Cheers

Yes, we have a couple of Z-Cell batteries, in a word, brilliant!

We have two of them, 10kWh each for a total of 20kWh of usable stored energy every day of the year.

I don't see any issues with discharge/charge cycles at all, can you elaborate? You may be thinking of their maintenance cycle which happens once every third day, which means you really need two batteries to go off grid. The maintenance cycle is where the bromine plates are cleansed completely and to do this the battery needs to be at zero charge. Once cleaned, you effectively have a brand new battery. It is this cleansing or maintenance cycle which gives them their longevity and at the same time keeps their storage capacity the same year in year out.

How the batteries work is relatively simple, although it is no doubt a complex process. When the sun is shining, the electrolyte positive and negative fluids, which are continuously flowing 24 hours a day, deposit zinc onto bromine plates. When power from the batteries is required, the system pulls the zinc from the plate and in doing so creates an electrical current. In short, it is an electroplating process; more or less. Now I'm not an expert on this, but as I understand it, this is how they work.

Warranty, well they are guaranteed to give a daily 100% charge/discharge cycle every day for 10 years, pretty simple from what I can see. Going on the amount of energy throughput, I would suggest our batteries may still be going for around 12 to 13 years with full 100% discharge/charge cycling.

At the end of the batteries life we can have them rejuvenated, then they are good for another 10 years, or they can be recycled. I believe their recycling is around 98% of all materials.

As for runaway fires, the active materials (liquid electrolytes) are fire retardant materials, so I am not worried about that. Apart from that, they are separate from the house and outside in the weather.

Their ability to work in extreme heat was another feature that helped tipped us a bit more towards flow batteries. They work in temperatures up to 50ºC they claim. Ours have worked in ambient temperatures of 47ºC in full afternoon sunlight in the backyard, their efficiency was down, but they continued to work and we powered the house completely from the batteries and solar; including air conditioners on a few occasions in the summer of 2019/2020. From memory the internal temperatures of the batteries on those very hot days was nudging 48ºC and their inbuilt cooling fans were going like the clappers; but they kept going.

The picture below shows the two batteries, plus two boxes which hold a Victron inverter in each. These allow us to pull up to 10,000W at a time. The most we have pulled was slightly over 9,000W during testing when the batteries were just installed. The Batteries State of Charge (SOC) when we did that test was around 4% SOC.

In practice we rarely go over 6,000W of draw, but sometimes when its hot and we have air conditioning on, then the oven, then the microwave, it will creep up towards 7,500W - 8,000W. The house normally uses around 300W to 500W with just background stuff on and the refrigerators (Kitchen and darkroom) and freezer. I have no idea how much power is pulled when I'm arc welding, I cannot read the readout when arcing up in the garage.

We have 7.7kWh of solar on the roof.

Mick.

210011_Batteries_and_Heat_Pump_Ilford_FP4_100_250mm_F22_Orange_Filter_004_Web.jpg

[damian]

If the tesla customer goes driving in the night they will need a mains connection to run things at home, fridge etc.


If you still have a mains connection that may or may not be ok, but I suspect if the home battery isn't TOO expensive people will still want it.


Up here at least the power companies are jacking up over grid feed in and are cutting tarrifs. I predict a time not too far away when numbers of people simply disconnect entirely.Good if you own a house/roof, not so much for apartment owners...