Solar for Beginners [ask your questions here]

graememk

https://www.boards.ie/discussion/comment/123338652#Comment_123338652

Things like that seems to be something wrong with the CT/meter that the hybrid inverter uses to measure the grid.

When the sun goes down does the house load go to zero too?

SmoosBoo

Not quite but pretty much.

graememk

https://www.boards.ie/discussion/comment/123338666#Comment_123338666

Then there's something not right with the inverter CT or meter (not your esbn meter, its a separate device that monitors the grid that the inverter can charge or discharge the batteries)

Likely just an oversight and should be a easy fix.

SmoosBoo

Thanks - I looked up CT/meter in another forum and someone there seems to have had a similar issue

“the CT clamp for the solar system was positioned on the wrong cable. The inverter was reading the power generated by the solar system and including it in the house load”

Hopefully it will be a simple fix like that!

Murph_D

https://www.boards.ie/discussion/comment/123338666#Comment_123338666

This was an issue for me too after a recent install - inverter graphs showing exactly the kind of pattern you describe. Seems to be a surprisingly common installer error.

SmoosBoo

Cheers - any idea how it was fixed. My installer is going back to their support to see how to fix it.

magicbastarder

i'm researching the various quotes i've been given, and the equipment supplied. and this is where my brain is.

https://www.youtube.com/watch?v=RXJKdh1KZ0w

magicbastarder

e.g. i have seen these two solis models on different quotes; with a price difference of €300 based on retail. but i have not got a clue why one would be better than the other.

https://www.solisinverters.com/global/rhi_inverter1/34629.html

https://www.solisinverters.com/ie/energy_storage_inverter5/S5-EH1P%283-6%29K-L_ie.html

Jonathan

https://www.boards.ie/discussion/comment/123338652#Comment_123338652

Can you post graphs to demonstrate?

SmoosBoo

See graph for end of March and so far in April. Plus graph for yesterday when there was little to no appliances in use apart from 5pm and 9pm

IMG_1639.jpeg

IMG_1638.jpeg

IMG_1641.jpeg

Soarer

Right.
For the past near 5 years, our average usage has been 22kWh per day.
For me, the way solar systems chop and change between using grid, panels, battery for both input and output is close to witchcraft.
In my head, our potential installation should have a minimum 22kWh battery to cover our usage, which we charge every night, and then use our panels to top up or export during the day. However, I’ve had a few installers out that have said that we’d be better off with a smaller “hard working” battery. I don’t understand that ‘cause in my head, something that’s had a hard life won’t last as long as something that’s had a handy life.
Can someone explain the rationale behind that please?

graememk

Really depends on cost of the battery.

The biggest payback factor in batteries with the current feed in tariffs is the load shifting. (Charge at night and export all excess),

The argument with the smaller battery working hard is that you can cycle the battery every day.

Whereas a big battery you may only cycle 3/4 of it.

But you already know your daily use is 22kWh, you'd be able to "use" the whole battery.

One thing I'd say, if your on the fence with the battery, look into the kits, get a hybrid inverter that works with many batteries, (don't lock yourself into brand only batteries). Or even the ready to go ones from the likes of gobelpower.

You'd get 15kWh for the price of 5 with a lot of the other ones on the market

Soarer

Thanks @graememk .

I've decided on the SigenStor system, rightly or wrongly. An extra 8kWh module would set me back approx. €2,500.

One of the other considerations I have is the inverter size and the "EV rates". The system comes with a 5kW inverter. I know they go up to 12kW on a single phase, but I don't know what we're allowed in Ireland. If I'm limited to 5kW and the EV rate is only for 3 hours, the most I'd pull down of a night would be 15kWh?

As for the cycling of the battery, are these systems clever enough force the battery to discharge to the grid once per (couple of) days? Would that solve a problem of my own making?! 🙃

DC999

https://www.boards.ie/discussion/comment/123346267#Comment_123346267

Bear in mind you can run household stuff and charge an EV and heat immersion during the cheap night rate while the battery is also charging. So battery won't need to run those during the day.

magicbastarder

https://www.boards.ie/discussion/comment/123346267#Comment_123346267

The system comes with a 5kW inverter. I know they go up to 12kW on a single phase, but I don't know what we're allowed in Ireland.

i was told you can go for a larger inverter, but the application process costs ~€1k.

but if you're charging your car at night off the mains, i don't think the inverter would be the bottleneck, it'd be the car charger itself (7kW)?

Soarer

https://www.boards.ie/discussion/comment/123346300#Comment_123346300

Ah ok, so maybe I'm getting this wrong? Don't forget, this is a beginner thread! 😉

Is the inverter only involved in the array side of things? So if I had 3no. 8kWh battery modules, and each one has a charge/discharge rate of 4kW, I could fill all 3 of them simultaenously in 2 hours since it's coming from the grid? Or at a slightly reduced charging rate across 3 hours? And top up the immersion if required (have thermal panels so usually have a bit of water)?

Soarer

https://www.boards.ie/discussion/comment/123346318#Comment_123346318

Thanks for that.

It's rare enough I charge the cars at home. I'm lucky enough to have charging in work. I only mentioned the "EV rates" as that's what the suppliers tend to call the cheap night rates. I'd be looking at that as a way to fill the storage batteries.

Soarer

So the clearances required for installation ie. 200mm from Velux, 500mm from roof edge, etc. Are they a requirement only if you’re applying for the grant? Or are they part of general building regs?

Also, the grant is €1,800 for a 4kW array or more. Does this have to be an optimum installation, or is it just 10no. 400W panels in any arrangement? As in, if someone was daft enough, could they put 10no. panels on their due north roof and still qualify?

gar

Is it possible to swap a Huawei system to dump the stored battery power to the grid before charging at night?

Can't seem to find how to do it?

graememk

https://www.boards.ie/discussion/comment/123351228#Comment_123351228

Doesn't matter aspect just the power of panels.

The clearances started as seai only, but I think it's part of the planning exception now

Soarer

https://www.boards.ie/discussion/comment/123351593#Comment_123351593

Ah ok, thanks.
I’d one installer tell me that only 30% was allowed on the non-optimum side to qualify for the grant! And this is a well established company!

As for the clearances, how sticky are they on them? Like, instead of 500, you were 460 each side? That’d be the difference between 7 and 8 panels for someone I know.

graememk

https://www.boards.ie/discussion/comment/123351765#Comment_123351765

The SEAI are pretty strict on them, if they inspect. But if the rails were made long enough.. and after the grant was processed and paid... Nothing stopping you squeezing another panel in after the fact.

North facing does effect the benefit to the Ber but for the grant there's no mention of it.

I think someone here did have a complete north face array installed as that was the shape of the roof

Soarer

Thanks Graeme.

That's what I was trying to get at with my original question. If you had 10no. panels that complied with all regs, and were rated at 4.4kW to meet the grant threshold, can you say to the inspector "thos couple on the outside aren't part of the grant process. Just those 10no.?"

Or is that a bit kuntish and only drawing trouble on yourself?

magicbastarder

Just been to the ideal homes exhibition. Big range in quality of the staff manning the solar stands. One basically said to us 'I'll just take your details and let an expert talk to you later in the week' whereas others actually knew their stuff. Or at least gave the impression that they did.

vaughanj

Are batteries worth it for every house or are there specific details that make them more worth it? Looking at getting 12x445watt panels (9 on south west roof, 3 on south East extension roof). House of 4 with about 8500 units electricity use a year. No EV yet, maybe in the future. Myself and other half work about 60% from home.

kelbal

https://www.boards.ie/discussion/comment/123352528#Comment_123352528

When doing the sales pitches, the companies were giving me overall projections about how the full panel & battery system would be saving me money, but weren't giving me specifics about how much the battery alone would save me. I'm paying 28c day and 14c night. By my reckoning, if I charge a 5Kwh battery at night, thats a saving of 5 x 14c (difference between day/night rate) = 70c saving. Then, if the battery is discharged during the day, yes the solar will top it up - but that solar could otherwise have been sold to the grid for 20c, so there's only an 8c saving per unit there. I'm struggling to see how the battery is saving more than about €1 per day, so thats why I didn't choose to get one installed. Just too slow of a payback on a €2100 device. Might reconsider in a few years if prices come down or technology improves. I'd love to hear a scenario though to show me how the savings are significantly better.

magicbastarder

as i was warned several times yesterday at the ideal homes, do not expect to be able to sell to the grid at 20c per unit for perpetuity - that's going to fall. the price of buying electricity will continue to trend upwards, but the money you get from selling it will likely trend downwards.

10-10-20

https://www.boards.ie/discussion/comment/123356974#Comment_123356974

It has dropped to ~9p over in the UK on Octopus Flux plans.

https://en.wikipedia.org/wiki/Duck_curve

Comer1

https://www.boards.ie/discussion/comment/123357010#Comment_123357010

How much are the paying per unit for import?

magicbastarder

https://www.boards.ie/discussion/comment/123357010#Comment_123357010

one of the sales guys claimed that in denmark (i think it was denmark) they actually charge you to backfeed into the grid at times.