Hot water cylinder and PV diverter/router

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kotuku4

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#204382 29-Sep-2016 11:13

Hi Looking for advice.

Have 180 low pressure water cylinder 20 years old.

4.9kw Solar PV, hot water is on a simple timer to heat during the day. Smallish house one bathroom, 5 people, we manage ok at the moment, and power usage is low.

Have priced hot water heat pump options, external pump to existing, replacement with external Bosch compress 3000 270l system. They seem too expensive, the Bosch $6867 plus building consent and electrical. Not confident of savings and long pay back period.

Now thinking perhaps I should upgrade to a 250 litre mains pressure cylinder and fit a PV router?

If I do this I need to acquire a router for my electrician to install, any recommendations? Have looked at the MK2PVrouter but it's kitset form is daunting, would prefer a propriety product ready to install.

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#1643180 30-Sep-2016 10:39

Paladin Solar Power Diverter?

http://www.paladin.nz/

http://www.trademe.co.nz/services/other-services/other/auction-1125737450.htm

Hammerer

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#1643252 30-Sep-2016 11:57

The economics of solar efficiency (both PV and thermal) point to getting a large water tank so you can use all the energy you generate. If you can get a bigger tank than 250l then you can use more of the output from the sunniest days. In Summer if you don't use much hot water then once you've fully heated the tank you won't be able to maximise the benefit of the electricity you generate.

I was interested to see that Energywise now has a calculator that estimates costs for replacing your water heating system and compares the different technologies. The results suggest, as you've already said, that some of the technology can cost too much up front to give a good economic return https://www.energywise.govt.nz/tools/water-heating/

timmmay

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#1643266 30-Sep-2016 12:24

A friend of mine has a solar system with PV diverter, but it's not as flexible as it could be. It does let power go to appliances and their three hot water cylinders, but it won't run anything on solar when mains power goes down.

Aredwood

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#1647478 7-Oct-2016 20:59

Here you go https://www.enasolar.net/hot-water/ Seems like a good off the shelf system.

Also get a 300L hot water cylinder. Every time I have checked the prices 300L has always been cheaper than 250L. Also get a twin element cylinder. Use bottom element for solar heating and top element for grid power heating. This means quicker booster heating. And on overcast winter days when the solar can't heat the cylinder fully. The solar heats the bottom to 30 deg or so. And the top element boosts it to 60 deg. Which is still a big power saving as not as much temp rise required.

kotuku4

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#1648296 10-Oct-2016 08:46

Thank you for the recommendations.

A 300 litre cylinder is not likely to fit the space I have, plumber said 250 is ok. Not sure if changing to mains pressure is a great idea or low pressure is better? My understanding is that mains pressure will deliver more hot water, faster and that cylinders won't last as long as low pressure. Both negatives as far as I am concerned.

Enasolar have emailed back for info on my inverter, to see if they can supply a suitable diverter. The Paladin guy has not responded.

Aredwood

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#1648766 10-Oct-2016 21:27

Check both HJ Cooper and Rheem stainless steel cylinders. As they do different versions of short and fat vs tall and skinny cylinders. Also recommend mains pressure. If your current cylinder doesn't have a tempering valve the plumber will have to install one on the new cylinder. These often cause shower pressure problems. And if your house is a 2 storey with cylinder on bottom floor don't even think about going with low pressure again. You can always put flow restrictors on your taps with mains pressure if needed. But often a lot more work to fix a non preforming low pressure system.

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#1648776 10-Oct-2016 21:47

A lot depends upon the starting point. Although I went with a low pressure replacement, I'd get mains pressure for a new build or complete renovation. We went from a 1950s header tank above the ceiling to top of the low pressure range with a pressure reducing valve. The result was a multiple increase in shower flows but nothing like the luxury of mains pressure.

We stayed with a low pressure system because it was economic and easy: no pipes need replacing or leaked; less wastage of water and electricity; tanks last longer, etc. But mains pressure can also be economic and easy: more and, I'd say, better and cheaper options for taps and shower heads; less noise than if using pressure reduction technology (e.g. valves, taps); less problems with low pressure; a broader range of flows are possible and sometimes you want or need them; etc.

I liken it to buying a bathroom exhaust fan. The more economic options are not as good and usually a lot noisier. So it is generally worthwhile spending more money to install a more expensive and better performing product.

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timmmay

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#1648869 11-Oct-2016 06:49

We put mains pressure into our very old house with no issues at all - nothing was changed other than the bathroom, which was a complete refit anyway.

kotuku4

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#1652649 18-Oct-2016 08:43

Hummm Enasolar are suggesting installed cost of around $3800 for Hot PV system (diverter and controller to work with my existing inverter).

Stan

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#1654798 19-Oct-2016 22:26

That Bosch compress 3000 sounds way to overpriced I know we can do just the unit for 3.3K ish with GST.

I would be interested to know how you get on with a diversion system I am not a fan of selling my extra electricity back to the grid.

kotuku4

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#1657542 25-Oct-2016 16:26

Okay I got hold Of Grant at Paladin and he offered a controller for $499 plus delivery and GST. So will try it and see how that pans out.

SumnerBoy

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#1657555 25-Oct-2016 16:53

Would love to hear how it works out for you. Looks like a good bit of kit, especially if you have an EV which you can use as a secondary dump load.

kotuku4

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#2003971 28-Apr-2018 11:28

I finally found someone to install my Paladin solar power diverter and I am happy to see it working.

The electrician with the original solar installer was booked in to install over a year ago but never showed up and I did not chase. He was not that interested, said the existing timer should be ok.

My usual electrician is bloody good value, but had no knowledge of solar or diverters. I found a solar installer who usually installs the Immersun PV router, Andrew from Sunshine Solar Blenheim.

The install took about three hours, the instructions were not great. We we lucky to be able to get Grant on the phone to check a couple of details. Andrew was happy to proceed and install the Paladin, although he though it was a bit basic.

Will monitor usage. I am also changing power provider from Ecotricity to Grey Power Electricity, as it appears be a better deal for me.

Aredwood

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#2004141 28-Apr-2018 15:34

Thanks for the update. Guessing that you will stay with the low pressure cylinder for now?

kotuku4

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#2004188 28-Apr-2018 17:17

Hi i upgraded to 270 litre low pressure cyclinder, due to a leak in the original 180.

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