Solar PV Hints, Tips & Troubleshooting

AndyBoBandy

Brilliant. Cheers for the replies.

graememk

https://www.boards.ie/discussion/comment/117882553#Comment_117882553

In your case, you would wire the sink element as Heater 1, and the bath element as Heater 2.

as it's the same thermostat controlling both elements, it would stop the power going to heater 2 (bath).

So the eddi should just be wired into the bath one.

A temperature gauge on the hot water tank is quite useful.

You could go further, and get a thermostat fitted to the hot water tank, and then in tandem with the nest thermostat, it will heat the water at the end of the day as needed.

garo

Usually the battery always has priority over the Eddi. The Eddi is smart enough that it lowers the amount it is consuming periodically and checks if this results in an export. If yes, all good and it goes back to what is was consuming. If no, it will consume less and then repeat by lowering consumption again to check if that results in an export. If you only have a 120l cylinder with I assume a 2/3kW dual element, you will find that the water will get up to 60C after an hour and a half of Eddi going full blast (i.e. nothing else on apart from house baseload). A small cylinder really brings the economics of the Eddi into question as You will only use a fraction of the excess in mid-summer.

Jonathan

https://www.boards.ie/discussion/comment/117882617#Comment_117882617

I was assuming a dual stat, dual element immersion, but yes, single stat dual element will suffer from that issue. Better to wire bath only, as you suggested.

@AndyBoBandy Another option is to get the relay board for the Eddi. You can then add two PT1000 sensors if you have suitable pockets in your cylinder. This will allow you to see the temperature in the tank. You could then go one step further and use relays on Eddi to call for heat from boiler.

slave1

As others have pointed out, a 120l cylinder is small for PV, if that works for you then fine but in Summer it will be topped up mid morning at the latest.

EDDI not economical in your case but I don't worry about economics when it comes to hot water, it's about convenience and self consumption of PV generation

AndyBoBandy

https://www.boards.ie/discussion/comment/117883403#Comment_117883403

120L is more than enough for the 3 of us. When we bought the house it only had a 60L copper tank, and we wouldn't get 2 showers out of it, but now we can get 2 showers and a bath, and there's still plenty of warm water left in it... It was effectively a free install as the hot press had to be moved anyway to accommodate the stairs to the attic!

The great thing about the new tank is it'll keep the water warm for a few days

So if as you say it's hot by mid morning, thats great as we can then get the battery topped up, as well as manually putting whatever's left into the car... I can dial the car down as low as 5amps / 1kW, so If I see I have a steady excess of say 1.5kW for a couple of hours during the day, it'll be no hassle for me to plug in and dial the car down to 7/8 amps, and then just stop it remotely via the app as the excess tails off... then if it's a regular thing, and there's always some excess, I'll go for a Zappi

Likewise we are not too concerned about the economics of it all, we just want a system in place that will ultimately reduce our monthly bills in the future, be that by reduced electricity bills over the year, as well as reduced gas usage over the summer as the Nest used to let you time the hot water in 15 minute increments, but an update a few years ago changed that so it's a minimum of 30 minute increments now.... so we do 1 per day over summer, so that's 3.5 hours of boiler usage per week for hot water over summer that'll hopefully disappear... (almost 70 hours of usage since the heating was last on)..

Our ultimate goal is long term reduced outgoings... we both have decent paying jobs, but they are stressful and we don't want to do it for very much longer, so we are trying to make hay while the sun shines... The plan is to go for a heat pump in about 2 years...

RingSting

2 showers and a bath from 120L?

Must be 4minute showers and a baby bath.

Currently upgrading from 120L copper to a 220L steel for 2 people .

AndyBoBandy

I'm sure it's a 120L tank!! Was actually looking for a receipt/invoice to confirm...

edit: I pulled out my receipts folder and the very first receipt that fell out was for the cylinder from October 2014.. maybe its a 160L tank as it's dimensions are 48" x 18"

(Gledhill Cylinder Se48x18Ind 48" By 18" 20Psi Insulated)

A quick Google tells me its a 162L tank, but either way, it's more than enough for us... and we have those big rainforest type shower heads...

RingSting

https://www.boards.ie/discussion/comment/117883682#Comment_117883682

Is that a picture of it ?

Because thats at least 220L in the pic

bullit_dodger

LOL !

Pi x R^2 x h = ?

AndyBoBandy

https://www.boards.ie/discussion/comment/117883689#Comment_117883689

yeah, thats the new tank I had installed.

far too early in the morning to be doing maths... but roughly 200L from a 48x18"" cylinder?

Blue4u

https://www.boards.ie/discussion/comment/117881738#Comment_117881738

The installer has come back anyway and said they are sending out engineer. They have been good previously so I expect they have checked online and seen an issue.

No LCD display, these are the two main boxes.

bullit_dodger

https://www.boards.ie/discussion/comment/117883792#Comment_117883792

Yup - 200L would be about right with those numbers. In reality, probably slightly less as there'd be I guess an inch of insulation (?) on the outside, so your actual "usable space" inside the tank would be 16" inches. Be about 160L of water.

AndyBoBandy

pretty much ties in with what I found on Google then... 162L capacity. Dont know why I had 120L in my head!!

THE ALM

I have just changed out the old 140l 25mm insulated cylinder for a 206l 50mm cylinder for the very reason that PV is going in and thankfully no leaks 😀

bullit_dodger

This maybe perhaps better suited in the plumbing forums, but since many here would have followed the same path with eddi installs, I suspect the knowledge is here?

I'm currently using the reliable Triton T90 which I'm sure many have here. I've also got a "shower mixer" outlet in the shower (unused currently) plumbed from the immersion tank. Problem is that the drop of 1-2m of water from the attic tank down to the shower head, that equates to only 1/5th of a bar of pressure, so am thinking I'll need a 1.5/2.0 bar boost pump. Anyone got any pointers, approx cost for install, and if they could PM a reputable installer that would be very helpful. Just need the hot press work done. Everything on the shower side is already there from previous owners. Many thanks.

garo

With an electric shower the water pressure also depends on how fast the shower can heat the water. Electric showers basically suck. If you are getting a pump might as well get a proper pumped shower and ditch the T90. And yes Plumbing is the right forum. Here's the master thread: https://www.boards.ie/discussion/2057860985/recommend-alternative-to-triton-t90sr-and-mira-qt-elite-showers/p1

bullit_dodger

Thanks for the link garo - I'll open a thread there.

As an FYI - I did consider ditching the T90, but then there's the problem of what to do on a cloudy day in the middle of winter where the eddi isn't getting any juice or enough juice to make a hot water shower from the immersion viable. For those days the T90 would be heating only the water that I'm actually using... and would be in effect a little more efficient than heating water than I'm not using via gas or grid sourced electricity. So my thinking was since it's not actually causing any harm (other than looking a little weird having two outlets in the shower) and removing it would leave a gap and more work for me to "fix" I'd leave it as is, but install a pump to improve the pressure for the immersion.

Again, thanks for the link.

garo

If you have a well insulated tank I wouldn't worry about the extra water being heated as it will get used. The temp drop on good tanks is lower than 0.5 degrees an hour. I have a gas boiler and a factory insulated tank and I just heat the water once in the morning and once in the wvening - yes we have people who love to take long showers.

graememk

Depends on the shower you get, some are designed with low pressure in mind and can go as low as 0.1 bar I think.

It does restrict flow but there is options there for you if you don't want to fit a pump.

bullit_dodger

Yeah ultimately removing the T90 is the "right" solution.

The tank is not bad insulated. 2 lagging jackets - wish it had integrated insulation, that hard plastic shell stuff (dunno what it's called) - but it holds the heat decently enough all the same. Removing the T90 though would involve tiling, waterproofing and closing off the pipes - which I'm not adverse in doing, but it's like path of least resistance at the moment. Everything on the shower side is plumbed already, just will hold off until doing a bathroom refit - so slotting in a 1.5 bar pump should see that whole problem solved.

DrPhilG

Solis users, quick question

Am I right in thinking that to prevent discharge on night rate, I just need to set a timed charge overnight? But at 1a so it isn't really charging at any notable rate, but it will prevent discharge?

jspuds

https://www.boards.ie/discussion/comment/117886687#Comment_117886687

If you get the latest software you can separate the discharge from the battery and the charging from the grid.

I have charging from the grid "not allow" and time of use configured which means the house runs off the grid during the night rate and doesn't discharge the batterry

DrPhilG

Nice. How do I get the software update?

jspuds

https://www.boards.ie/discussion/comment/117887132#Comment_117887132

email euservice@solisinverters.com, eu-service@solisinverters.com & europe-service@ginlong.com with your model and serial number and they will do the update remotely. Also mention you are based in Ireland as some of the software versions can depend on your location.

I got mine updated to version 35 last week.

DrPhilG

Cheers, will do.

slave1

https://www.boards.ie/discussion/comment/117886438#Comment_117886438

Turn your shower to coldest setting, if there’s plenty of pressure then fitting a pump is no good as your pressure is being lost from heating the water, remember these showers are designed for low pressure systems…

graememk

https://www.boards.ie/discussion/comment/117888104#Comment_117888104

I've a boost pump for a shower, it's a dual chamber one, pumps hot and cold.

The shower does have a dedicated hot and cold supply though (one pipe straight from the cold water tank and another from the hot, nothing else on the line)

RingSting

If you are doing some replumbing use bigger pipe as far you can then reduce to 1/2" .

bullit_dodger

https://www.boards.ie/discussion/comment/117888104#Comment_117888104

LOL - naah you guys are missing the point. :-) Although I do appreciate the willingness of people to help. It's one of the best traits of boards.ie if you ask me. For reals.

I'm hesitant to continue as it's a little off topic, but if you'll indulge me to clear it up. The T90 is fine. Works well and has performed admirably over the 7 years I've lived here since I bought the place. It's the usual 3-4 liters/min which you'd expect for this type of thing. Shower looks like this.

2021-09-14 11.34.21.jpg

I inherited this layout when I bought the place. The 2nd mixer goes back to the immersion tank, and considering I'll shortly have an eddi etc, that means that I'll have hot water available in the tank and the need to use the Triton is removed as I'll have hot water there. Problem is, is that the shower is on the same vertical height as the immersion tank, and since there's only maybe 1-2 meters of "head" to the top of the tank in the attic, the pressure is pants on that lower mixer. Needs a pump as it's only 1/4 bar I guess.

Hence my desire to get a pump in. I could in theory remove the T90 after doing do, but then I'd have pipes to close off, tiling (assuming I have spares tiles), waterproofing etc so I'll probably just leave the T90 there for 8-9 months of the year where it will be unused due to the eddi.