Solar for Beginners [ask your questions here]

slave1

Just lay all the cables for the Zappi so it will be a straighforward install when required, 6sq cable and two runs of CAT6

Get them to put up as many panels as possible and consider optimisers for shadows during times of high generation

AckwelFoley

My god. Nobody warned me about the obsession with looking at how much electricity these things produce and cloud watching.

I'm know, it's only day one. Hopefully it wears off after time. I'm getting nothing done

slave1

It won't.....

MAULBROOK

https://www.boards.ie/discussion/comment/119585032#Comment_119585032

3 years in and I'm still at it

AckwelFoley

Disregarding figures and payback etc..

What is the max amount of panel wattage you can have with a 6kw solis hybred inverter.

Poor days one will get higher return, in really good days, when panels generate say 9kw/h what would happen in this instance with a 6kw inverter?

graememk

https://www.boards.ie/discussion/comment/119605167#Comment_119605167

It will clip to 6kw, The power just wont be generated. Its not like it has to go somewhere.

slave1

Rule of thumb, you can go 1.5 times inverter size but I'd only go say 8kWp on a 6kW inverter.

slave1

I just worked mine out, I've two 7.4 kWp feeding two 6kW inverters, could not go any higher due to voltage constraints

AckwelFoley

https://www.boards.ie/discussion/comment/119613594#Comment_119613594

2 inverters. Are these working simultaneously, or for one east one west string?

slave1

Simultaneously with export management

micks_address

hey folks - re using excess solar for car charging.. i know folks mention zappi can do this by default.. but if you don't have a zappi charger.. can you set up solar so excess only will go to the car if you leave it plugged in?

DC999

https://www.boards.ie/discussion/comment/119616090#Comment_119616090

Hey, not sure I get you. Once the Zappi car charger is setup by the installer (with the CT clamps on it to see when there is excess from solar that the house isn't using), it will auto divert that spare to the EV. As in the Zappi (or an equivalent smart charger) manages that itself.

If you have a car charger already, you check can if it charges from solar. Will be in the marketing blurb or on their site. Or call your installer. But I guess it's unlikely to do that unless you bought a more expensive one future proofed for solar.

If not, you can always get something like a Zappi and sell the one you have. Won't get a grant the 2nd time.

I have a Zappi and it's amazing. You can see the Zappi gets the electricity meter 'balanced' to use basically no power from the grid as the excess goes into the Zappi (depends on the charging setting you pick of course). So during the summer months our car charged for free a lot of the time (same as having a free 'petrol station' in our house). Am sure there are Zappi competitors, but I don't know them.

Mr Q

https://www.boards.ie/discussion/comment/119616793#Comment_119616793

There are a few alternatives to the Zappi alright that will do similar. But I don't think any are as cheap, priced a Zappi at 847 recently.

The VW mid spec and higher version one were supposed to be capable of it but I am not sure if the feature ever worked.

micks_address

https://www.boards.ie/discussion/comment/119616865#Comment_119616865

yeah i have the mid spec vw charger... guess i didnt think id be looking at solar... but then again i might not be for a while.. curious what options are out there..

DC999

I'd suggest separate the decisions so it's not holding you up. Can get solar without it.

You can always leave for now and get it done in Year2,3 after solar is live. You can still charge the EV. You might not lost much € wise. So if your night rate (to charge the EV) is close to the FIT rate (for excess power you would've sent to car), you're not losing out. And you know / can find the number of units you use on the EV now. I wouldn't leave it that way forever, but can get solar quotes with and without the Zappi (or equivalent) to compare.

You'll deffo flog a car charger. Just depends on the amount you get. Heaps of people getting EVs.

micks_address

dont really want to change the car charger... either way im not charging a lot at home but that might change in the future as well.

micks_address

https://www.boards.ie/discussion/comment/119618066#Comment_119618066

i guess you run the granny charger from the invertor? ive seen a few people talk about a socket being add to or on the invertor? i know would only get 3.6kw but sure would be better than nothing

AckwelFoley

https://www.boards.ie/discussion/comment/119620553#Comment_119620553

The solis inverter has a backup outlet. So we can wire in a socket into the house that in the event of a blackout we will use the battery. So plug in a light and the TV.. or the slow cooker the 5kw battery will easily cover the consumption

AckwelFoley

When laying the cables from the house to the Man shed deluxe beside the house I went nuts. I had already dug up the utility twice before in the last 10 years, this being the 3rd time its not going to happen again. I ran the cables out to the inverter in the upstairs of the shed through duct and then, layed a spare 4 inch and a spare 2 inch duct for whenever or whatever.

So when the electrician mentioned a new wire to be ran to the house for back up.. I smiled and said this won't be a problem..

graememk

https://www.boards.ie/discussion/comment/119620797#Comment_119620797

I know that feeling! Always leave a rope in the pipe!

AckwelFoley

https://www.boards.ie/discussion/comment/119621822#Comment_119621822

Pro tip.

Use wire, a mouse won't chew through wire and it won't deteriorate. Rope alright if you're pulling in the foreseeable future but it could be next week or 20 years before I need to again.

But yea.. it would be easily forgotten, particularly if running a few cables in, forget to leave a means to pull the wire next time around

daheff

I hope you all don't mind, I have a question in relation to hot water diverters.

We bought a house with 5 *278w panels. I've never really seen the panels generate more than about 1kw (I have a zappi car charger which has a pv clamp so I can see how much is being generated).

If we were to get an Eddi (or other diverter) to use excess to heat water, is there a minimum amount of solar power needed to be generated for the eddi to kick in?

I'm wondering if it's worth it to get a diverter to heat water when there's excess.

If I'd need to be generating>2kw then it's a nonstarter as the set up is.

graememk

https://www.boards.ie/discussion/comment/119623633#Comment_119623633

The eddi can go down as low as 100w

On the flip side, do you see much export on the myenergi app?

That's the amount that the eddi would put into the hw tank.

An immersion running flat out for an hour would use about 3kwh.

Eddi is around 500 euro, say night rate electric at 10c, (ie if you just timed your immersion to come on before night rate cut off) it would take 5000kwh for it to start saving you money.

Maybe if you had a big array with lots of export and high water demands, but on a 1.4 kwp system it's not gonna be worth it.

daheff

https://www.boards.ie/discussion/comment/119624427#Comment_119624427

Thanks for your response.

I don't have the myenergi app to check how much is going into the tank. Also don't have nightsaver rates either. Latest I can see is charged at around 38c (inc vat).

So how does the eddi heat the tank? I thought the immersion needs around 3kw to work? Does the eddi just turn on immersion with the excess solar and use grid to make up the deficit?

Eg excess solar is 0.5kw. immersion needs 3kw to function, so eddi turns on and draws 2.5kw ?

Or am I missing something?

Gerry

The element will attempt to draw 3kw if you supply it 230v. This is approx 13 amps of current.

The amount of current that flows is governed by the resistance of the element. From the above and with the formula (voltage divided by current = resistance in ohms )

we get 230/13 = 17.7 ohms

Eddi will only supply the excess power and it does this by generating an ac output at a lower voltage.

The resistance of the element is still the same.

So, a lower voltage will not flow as easily, the current will be lower and the total power will be lower.

so lets say in your example 0.5kw of excess, Eddi would generate ac with a voltage of 95 volts

The element will manage to draw 5.3 amps of current

and 95 x 5.3 is about 500 watts

<edit> numbers are approximate, I typed this on my phone.

Cross checked this to find the formula which Eddi would actually use to determine the voltage

So once it knows the target power, and the resistance of the element, it can then calculate what voltage to generate at.

</edit>

graememk

https://www.boards.ie/discussion/comment/119625315#Comment_119625315

I should have known but didnt until I actually wrote the figures down. Resistance cant change but the other 2 can, totally forgot about resistance in the calculation. initially thought it always drew 13 amps. Should have brushed up on my LC physics!

Eddi and solar diverters only work on resistive loads only, for this reason

Gerry

Yeah I'm used to most of those calculations, and I guessed at values which would make the example work, the calculation for target voltage is not something I'm used to. While looking that formula up I'm reminded that resistance increases with temp so your immersion might draw less as it gets towards target. The solar diverters really are smart pieces of kit. The economics still doesn't quite work for them for me vs gas pricing but that can change.

The other option I was considering was adding a separate hot water heater of a lower power - say 1kw, and controlling this via home assistant.

slave1

Putting science to one side I'm of the opinion that low excess into the EDDI is pretty useless, e.g. 300w excess for 5/6 hours on the darker days (Winter is coming) had fek all impact on the tank as a whole and doesn't really heat up the water

ELM327

https://www.boards.ie/discussion/comment/119626557#Comment_119626557

True but better than sending it to the grid

DC999

https://www.boards.ie/discussion/comment/119623633#Comment_119623633

If you're worried that unused power is going some where, as others said here there are other places to send it.

1) get paid the FIT 2) send to EV (assuming it's in driveway during day. You have the Zappi that does that.

1) Check that the ESB got an NC6 cert from whoever installed the panels back in the day. Then you are entitled to the FIT payment for any unused units (which won't be much on a 1.5kWp setup). Search for 'NC6' on the forum and there's an ESB email to send to and ask them to confirm they have it. I recall seeing that, but not an email address I know. Then you get paid FIT payment on what is spare. But if you don't have a smart meter, you get the deemed export (which will be worth more).

2) You can install the My Energie app to link to the Zappi. Gives good starts on how much free power there is (but you can also see that on whatever other meter it seems as you said you can see it rarely gets about 1kw). Go to myenergi.co.uk and will find the info under the Zappi help section. And you can then use the app schedule it to charge at times of the night (on cheap rate if you get it). In case you didn't know, can also set it to eco+ mode (on the zappi or the app) so it takes the excess from solar and uses that to charge the car. Will still need some from grid as needs at least 1.4kw spark from solar which your system won't have most of the time.

3) Bonus to save $s. And if you're still on a 24hr meter and have the EV, it's liked costing a lot to charge. Our EV uses close to as much power as our house. So move to a day / night meter (which means you lose the FIT I mentioned above but will save on cheaper juice). Again, there's a thread just on that. Or get a decent smart tariff (if you can find one) with a cheaper night rate. Again, there's a thread on that.

Cheers