Solar PV Hints, Tips & Troubleshooting

thomas 123 · 05-10-2021 12:13pm

Thanks for the advice lads!

From what you guys are saying a 6kWp system with or without a battery should be the way I go.

The quotes thread is great but I need to know what I am after before cherry picking ones I think will do it.

This leads me to my next question - battery or no battery? With rising electric prices the battery seems like a no brainer to me , what are the pros and cons bar the initial outlay of the battery?

Bobeagleburger · 05-10-2021 12:36pm

My battery seems to be slow charging today.

Power is currently at 3.84kW, but battery only charging @ 0.429kW. Less than 1kW going to the house, and the rest to the grid.

Battery is 2.4 pylontech and usually charges at a max 1.2kW or thereabouts.

Any ideas?

garo · 05-10-2021 12:37pm

If you can fit more than 6kWp of panels go for it. Production varies a lot depending on season (and thus the angle of the sun at noon). And panels are relatively cheap. Getting them all installed at the start is much better than bringing someone back in later. Note that there is an export limitation of 6kW so you shouldn't install an inverter that can output more than 6kW but it is possible (and completely safe) to oversize you panels vis-a-vis the inverter. Lots of people here have 7 or 8kW of panels with a 6kW inverter.

Batteries require a Hybrid inverter which is about 600-800 more than a normal inverter. Batteries are useful for your evening consumption in the summer once the sun is low in the sky or has set. You can also charge your batteries at the night rate (if you have a day night meter) and discharge them during the day. The payback on batteries ranges from 5 for a DIY build to 10 or even more depending on how much they cost you. Ultimately whether they are worth it depends on how much they will cost you. Ring around for some quotes and then post in the quotes thread to check if the price is ok or not.

bullit_dodger · 05-10-2021 12:45pm

Hey Thomas. So yeah, a 6Kwp set of panels will, for all but a small minority of super large consumers, see you right. To be honest though, I'd advise you to go back a little upstream and have a look at your usage. Your ESB bill is the 1st place I'd look. See how much units you are using currently. I know you mentioned it's a new build, but if you are living somewhere currently and the family is moving into the new build, your existing usage would be a good start.

Opinions differ on batteries. If you are of a technical mindset and like a challenge, I'd probably go for a smallish battery (~2.5Kwh), take advantage of the grant and then sell on and provision yourself a DIY battery where you buy the cells on ebay/Aliexpress. This, for most people, is beyond their technical expertise - or even if they have the skill, they simply may not want to do that .... so I'd advise a mid-sized battery (~5Kwhr). Nothing "wrong" with a larger battery, but unless you have the usage per day, you will end up buying something that you probably don't need.

Really your usage, or expected usage drives the whole thing.

DrPhilG · 05-10-2021 12:46pm

https://www.boards.ie/discussion/comment/117978914#Comment_117978914

How cold is it at the battery location?

I had that previously and it was because the attic temp was too cold so the charge slowed down.

Bobeagleburger · 05-10-2021 12:51pm

https://www.boards.ie/discussion/comment/117978961#Comment_117978961

The battery is in the attic. Not sure of the exact temperature today up there, but the temperature outside has noticeably dropped today,so you may be spot on.

How did you verify low temp was a problem for yours, and what was your solution?

Thanks

DrPhilG · 05-10-2021 1:01pm

https://www.boards.ie/discussion/comment/117978985#Comment_117978985

After asking around I got a few suggestions and the temperature one made sense so I put a stat up there and it was getting very cold overnight, as low as 3-4°.

I only had the issue a few times as you need an odd combination of low temperature plus enough sun to generate excess.

This year I'm going to build a box out of foam insulation to keep the temperature up.

garo · 05-10-2021 1:08pm

My inverter logs the battery temperature and that is how I noticed that my Pylontech 2.4 charges slowly in cold weather. As it charges it should warm up and go to 1.2kW charging speed. Today my battery went from 17C at 8am to 23C when it finished charging at 11.

SD_DRACULA · 05-10-2021 1:32pm

https://www.boards.ie/discussion/comment/117978837#Comment_117978837

This is my battery usage in 5 months and a 5kwh battery so you can get an idea - but also everyone is at home during the day due to wfh etc so it depends on your setup.

5kwh is not enough for my usage and even 10kwh would barely cover it so I'm leaning towards DIY lifepo4 route

Bobeagleburger · 05-10-2021 1:38pm

Thanks to you both.

I'll keep an eye on it, but I'd say you are both 100% correct.

thomas 123 · 05-10-2021 3:13pm

https://www.boards.ie/discussion/comment/117979175#Comment_117979175

https://www.youtube.com/watch?v=atYZ4RtUJhU

I think its time to practice this.

I have an idea now of what needs to be done, thanks all again!

irishchris · 05-10-2021 8:02pm

https://www.boards.ie/discussion/comment/117977430#Comment_117977430

Yes I have a ground mounted hybrid system and roof standard system. The excess that is not being used from the normal inverter array will always go to my hybrid inverter to charge the battery. Often will be producing say 2kw from the hybrid arrays and battery will be charging at 3kw as uses the spare solar power from the other system.

Strangely though tested with the DC switches off on the hybrid arrays and it diverts the excess from the standard inverter to the grid and battery stays static.

garo · 05-10-2021 8:54pm

https://www.boards.ie/discussion/comment/117979840#Comment_117979840

Look at the Solar Battery Options thread. I just bought 10kWh of batteries and plan to build it this weekend.

graememk · 05-10-2021 9:49pm

https://www.boards.ie/discussion/comment/117980938#Comment_117980938

with the solar switched off, that is odd behaviour, Must be because the hybrid inverter is "idle" when there is "no" solar.

Some evidence that there is no DC DC conversion in the hybrid inverter to charge the battery. Solar DC -> AC -> battery DC.

championc · 06-10-2021 7:38am

https://www.boards.ie/discussion/comment/117978158#Comment_117978158

And the bigger the system, the less likely you are to be able to self consume all power generated, especially on those sunny days.

thomas 123 · 07-10-2021 1:41pm

https://www.boards.ie/discussion/comment/117982045#Comment_117982045

Im sure I could find a use for any excess energy if I managed to get it to that point.

Another question, say during the winter I want to charge my batteries during the night utilizing the night rate - is that possible? What sort of a system would do it? Any videos of same?

MAULBROOK · 07-10-2021 1:45pm

https://www.boards.ie/discussion/comment/117988170#Comment_117988170

Yes I'm currently doing that now, started doing it last year and it did make a difference to our bill.

Solis inverter.

thomas 123 · 10-10-2021 3:37pm

Researching further today, I have a usable south facing roof of between 75-100 SQM , with my ultimate goal being to be as self sufficient as possible when it come to electricity production would that be enough space for a large system?

Bobeagleburger · 10-10-2021 4:20pm

https://www.boards.ie/discussion/comment/118001168#Comment_118001168

That should give you a big system!

Easily 10kWp and probably more.

South facing too. Superb potential.

jkforde · 10-10-2021 9:48pm

Screenshot_20211011-193132.png

https://www.boards.ie/discussion/comment/117988187#Comment_117988187

I opened a thread asking about just this.. in the Solis, do you configure it in the Adv Settings > Storage Energy Set > Self Use? And outside of any saved time periods, it just defaults to normal self use priorities.

reklamos · 12-10-2021 9:46am

https://www.boards.ie/discussion/comment/118002400#Comment_118002400

Self Use mode is most suited for us unless you have battery and want to use backup port and reserve capacity in case of power cuts.

AndyBoBandy · 12-10-2021 9:58am

Hopefully getting our system installed later this week!!!

Getting an Eddi as part of the install, so will pick up a MyEnergi hub tomorrow, and might grab 1 or 2 Harvi's too

I want to understand how the CT clamps will be configured;

1 on the Solar feed? will this be before or after the inverter?

1 on the house load at the fuse box?

1 on the feed to the battery?

Then I'd like to add an additional CT/Harvi to the (non Zappi) EV charger so I can see what it's drawing?

Also, I understand that Solar invertors are designed to shut off during a power outage for obvious reasons, so does that mean they will also stop charging the battery? or would they continue to send power to the battery independent of the house? I know during a power outage I'll be able to plug basic low consumption items into the battery, but would like to know if the battery could be still topped up if there is no grid power.

Jonathan · 12-10-2021 10:29am

https://www.boards.ie/discussion/comment/118007934#Comment_118007934

One CT on the AC side of inverter.

One CT to measure house load, either at CU, or meter box.

CTs can only measure AC, so unless you are getting an AC coupled battery, they can't be shown on the myEnergi app.

Power can be supplied from inverter during power cut via EPS output. Grant requires a fireman's switch. Once you get your grant, you could in theory get a generator cutover switch an power whole house.

Where are you buying your myEnergi equipment from? Need to pick up a Eddi relay board, but postage is crazy.

AndyBoBandy · 12-10-2021 10:43am

I was going to pick up the MyEnergi still from CT Electrical, I believe their Ballymount store hold MyEnergi products in stock.

slave1 · 12-10-2021 11:19am

https://www.boards.ie/discussion/comment/118007934#Comment_118007934

The EDDI will come with one CT in the box, so might save you a few quid

Jonathan · 12-10-2021 11:57am

https://www.boards.ie/discussion/comment/118008139#Comment_118008139

Can you check when you're out there if they have the Eddi relay board in stock and how much? Ta.

AndyBoBandy · 12-10-2021 12:21pm

https://www.boards.ie/discussion/comment/118008329#Comment_118008329

The system will need at least 2 CT's right? Inverter & House load, so I presume the lads will add the additional CT, and plug them both into the Eddi?

The Eddi can only take 2 wired CT clamps right? so if needing/wanting a 3rd, I'd need the Harvi?

Also, when buying the Harvi, do you need to buy the actual CT clamp for it separately? think they're around €19

Jonathan · 12-10-2021 12:29pm

https://www.boards.ie/discussion/comment/118008625#Comment_118008625

They might decide to just use a Harvi rather than trying to run cables back to the Eddi. Yes, Eddi only has two CT clamp inputs. Zappi also has another two (when you decide to swap out your existing EVSE and go all myEnergi 😜).

I don't think the Harvi comes with any CTs in the box.

DennisZ · 12-10-2021 1:02pm

Thinking about something strange - to have ESS between the grid and the house.

Zappi stays where it is - connected at meter box.

Solar inverter (non-hybrid, 5kw) stays where it is as well - connected at consumer unit (fuse board).

However the main power line going to the consumer unit will be routed via ESS with transfer switch (like Victron Multiplus/Quattro, will have to limit the export somehow).

Is this a plausible/allowed setup ?

AndyBoBandy · 12-10-2021 1:28pm

https://www.boards.ie/discussion/comment/118008655#Comment_118008655

The thing is the Eddi will be located almost directly below the inverter. I want to mount the Eddi on the outside of my hot press as the room is my office, so don’t mind having it there. Inside will be too hot.

Then the consumer unit is on the dividing wall directly under my office too, so it’s not a huge distance either… so probably ideal to run wired CT clamps, especially if the feed cables will be on the same run.

I might have the lads connect a 3rd CT clamp at the feed to the EV charger, and then I can just add the Harvi later up in my office.

Solar PV Hints, Tips & Troubleshooting

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