Electric panel resistive element water heating

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Re: Electric panel resistive element water heating

Postby offgridQLD » Fri Nov 04, 2016 4:54 pm

No, no reflector or plate. Something about them not doing much once dirty and full of leaves. (big issue in my location) I'm sure they would be of benefit when new and like you said strengthen the frame.
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Re: Electric panel resistive element water heating

Postby australsolarier » Fri Dec 16, 2016 7:38 am

Kurt,
just wondering if you fell down a ladder whilst doing the solar hot water installation. would like to know how you are going. thanks. urs
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Re: Electric panel resistive element water heating

Postby offgridQLD » Fri Dec 16, 2016 8:40 am

No it sits in the shed gathering dust to date. I will get stuck into installing it in the new year. Should have it in by the end of Jan.

I have 4x 40kg gas bottles to burn through and give back before I need it in so no pressure.

Kurt.
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Re: Electric panel resistive element water heating

Postby APR » Fri Dec 16, 2016 11:36 am

After looking at directly connecting panels to a resistive element HWS, and even going as far as fitting an extra 2.5kW of panels on the northern roof to power the element, I decided to go whole hog and fit another inverter with more panels to give me more 240v AC to get me through winter and to increase export through the warmer months.

A few months ago I changed over to Enova Energy for my electricity, and interestingly, they will be offering 12 cents/kWh for exports as of January 1st, so the repayment period I calculated for the new inverter and panels has reduced significantly.

Also, I was recently given a Rheem 80 litre resistive element HWS fitted with a 3,600w element that I may install to increase the hot water storage capacity. As my existing HWS element is also 3,600 watt, a second 3,600 watt element was not acceptable.

I went looking for another element, but the smallest element I could find to bolt straight into the Rheem 80 litre tank was 1,800 watt, and this is still more element power than I was wanting. Currently I am using a power diverter to send excess solar generation, that would otherwise go to the grid, to the HWS, but it is set up to handle a maximum of around 5,000 watts of energy and If I do connect this second HWS to it I don't want to overload it.

After looking around I came across a screw in element that is actually 2 elements of 1,200 watt each. So, 2 elements in parallel will draw 2.400 watt, one element by itself will draw 1,200 watt, and the 2 elements in series will draw 600 watt. To heat 80 litres of water by 45 deg C will use around 4.3kWh, and take a bit over 3.5 hours at 1,200 watt. Rather than connect this element to the excess solar power diverter, I would be happy to have this element on a timer and run it from 10:30am to 2:00 pm at 1,200 watt, as even in winter my upgraded solar system should power it OK without using grid power or pulling power from the batteries.

The element....
Image

The adapter....
Image

The adapter is fitted using the same sealing rubber gasket as used with the original element, and the retention plate and bolts used to retain the original element are used to retain this adapter. The element is sealed in the adapter via an "O" ring of more than adequate temperature and pressure rating, and there is plenty of clearance between the outer ends of the element threaded electrical connectors and the cover plate.

The tank is still to be plumbed and wired up, but I intend to have my existing 250 litre tank feeding hot water to this tank, so while ever the larger tank is getting up to full temperature this small tank will not have to do much heating.
2 x Goodwe GW5048D-ES Hybrid inverters, 13kW panels, 20kWh LiFePO4
Mk2 PV Router feeding excess solar generation to a 3.6kW 250 ltr HWS
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Re: Electric panel resistive element water heating

Postby huntercg » Fri Jun 09, 2017 7:21 am

Reviving an old thread. 34by151 did you do anything special with the earthing of the hot water system you connected the techluck controller to? What size enclosure did you use to dissipate heat? I have got 6 x 250w Trina panels that I acquired cheaply and want to connect to a spare HWS I have got in my shed. This will be in series with my existing grid connected HWS.
Cheers
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Re: Electric panel resistive element water heating

Postby 34by151 » Sat Jun 10, 2017 7:51 am

both the solar panel rails and the hater tank body are connected to earth.
The element is fed by the DC and is isolated from the tank body
The mechanical thermostat has been removed and replaced by a Resol controller

The solar panels connect to the tech luck controller.
The output goes to the element via a contactor
The contactor is controlled by the Resol controoler

I only use the resol for a thermostat. I dont have a solar tubes in the system or water pump connected to the controller.

For the enclosure i used one like this as I had it lying around the shed.
http://www.ebay.com.au/itm/400-x-400-x- ... ZdQjC8tdcQ

It houses the techluck, contactor, resol controller, 240v light switch and power point.

Cheers
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Re: Electric panel resistive element water heating

Postby australsolarier » Sat Jun 10, 2017 8:39 am

i looked into that techluck thingy a while ago. the energy transfer is much less than optimal. although much cheaper than the sunflux. and you will need a backup. (justin case is an interesting case)
i think there is no cheap cheap way around this. my preferred way i would do this is using a heat pump. can be easily programmed, turned on and -off, has soft start and uses one third to one quarter of energy. and doesn't monopolise the inverter when islanding.
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Re: Electric panel resistive element water heating

Postby australsolarier » Sat Jun 10, 2017 8:39 am

Kurt,
just wondering of your heat pipe system is still gathering dust in lieu of sun rays.
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Re: Electric panel resistive element water heating

Postby 34by151 » Sat Jun 10, 2017 9:53 am

I will also add I do have a backup to the techluck

The upper element is connected to the off peak power via the resol controller
However the breaker to the upper element has been off for well over 12 months without any need to use it.

Experiences may vary depending on where you live. I am on the QLD Sunshine Coast which is a factor.

Cheers
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Re: Electric panel resistive element water heating

Postby australsolarier » Sat Jun 10, 2017 10:04 am

yes and it also depends on how much hot water is being used. i have heard the statement " i am having a shower every 3 months whether i need it or not, having too many showers is bad for the health of the skin". i am finding on my solahart system, most of the heat is lost through the skin of the tank rather than usage.
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