Domestic Solar PV Quotes 2022 - No PM requests - See Mod note post #1

micks_address

https://www.boards.ie/discussion/comment/120474907#Comment_120474907

They actually less than the 9.5 capacity as the 5.2 only has 80% usable versus 100% of the 9.5 so something like 8.32 usable with 2 5.2

deezell

https://www.boards.ie/discussion/comment/120474992#Comment_120474992

No, he asked were two 5.2kwh batteries inferior to one 9.2 kwh hour batteries, as he was misled by the spec sheet current charge rate of ONE 5.2 at 50A compared to the current rate of the 9.2kwh at 80A The current charge and discharge rate of the two batteries being substituted for the single larger battery is 2 by 50 A, 100A. Your original answer referenced 'the smaller one' as being insufficient, missing the point that there are two, not one of these.

His other point relating to the difference in DOD,depth of discharge, is moot, as this is a long term issue regarding the life cycle of the batteries. The large one is rated ten years even if it is 100% charged/discharged in use, which would rarely occur. The smaller models are rated ten years provided their DOD is 80%, which is more likel real life use on average.

bullit_dodger

https://www.boards.ie/discussion/comment/120475061#Comment_120475061

Not sure that's entirely true Mick. The 9.5Kwh is actually a 10.xKwhr battery under the hood. They give you extra capacity (similar to the 8.2Kwh being actually a 9.4kw or something) where they basically "build in" the loss of performance over time and how they can guarantee that you'll still have 9.5Kwh in 10 years. So you buy a 9.5Kw and even though in 10 years it'll have lost 10% (more?) capacity, it'll still be 9.5Kwh.

The smaller batteries though don't have that "feature".

HotSwap

https://www.boards.ie/discussion/comment/120475146#Comment_120475146

That’s not how it works. You don’t just add the two 50A together to get 100A.

The 9.5 unit is the gen 2 battery from GivEnergy it’s a superior product it’s as simple as that.

If the The installer knew that he was going to be putting the 9.5 battery in the attic when they issued the quote and accepted the business it’s not the customers issue. I don’t personally like installing batteries in attics; but that’s a different discussion

Even in terms of the cost it’s more expensive to buy a single 9.5 Vs 2 x 5.2’s.

And discharge below 20% of a 10.4 kWh system in winter in Ireland will happen frequently if not every day in December and January.

deezell

The ability to cascade batteries and the resultant increase in capacity would depend entirely on the BMS of the units, and the interconnection to the inverter. I would expect the units to be cascadable, and to draw down power to an extent close to the additive maximum. However, DC power combination and switching is complex and not lossless. He should discuss this with the installer, as I suspect the older units are indeed a lesser solution that the dedicated larger unit. He would want assurance that the two units are designed to operate in tandem. And not just sequentially. He might also be due a refund if they collectively cost less than the next generation unit.

HotSwap

https://www.boards.ie/discussion/comment/120475979#Comment_120475979

The installer is the one trying to convince him it’s an equal solution. He’s not going to get a straight answer from them if they even know the answer. My last post on this question.

bullit_dodger

I see absolutely no issue in running 90% discharge on a Lifepo battery. Would even push it to 95%. A normal Lithium battery sure 80% makes sense, but the voltage curve is pretty flat on a Lifepo battery. If I'm wrong....fine! I'll let you know in 10-15 years - LOL.

The point however with the quote is more the fact that the supplier seems unwilling to try and negotiate a 110Kg battery pack into an attic. That's really the key point. If you can't physically do it, then the options become more limited. 2 x 5.2Kwhr batteries wouldn't be my preference over 1 x 9.5Kwh either, but is it vastly inferior?

No - I'd argue it's not. If you are getting it at a decent price and your comfortable with the supplier. Go for it. If not, then you'll have to decide if spending more money with another supplier (who might still have access issues with 100Kg battery into your attic?) is worth the higher discharge rate. Some of this will be down to your consumption profile. If your 2x5.2 Kwhr batteries are dead at 9pm, then having a 1x9.5Kwr (with higher discharge rate) empty at 8pm is a moot point.

Trojan00

The supplier has agreed that the 2 x 5.2 kwh batteries would have a lower charge/discharge rate (2600w). They say that the 9.5kwh battery is 4100w. I am not sure about that based on the spec sheet. I think it is 3600w. Anyway, we seem to have come to a new plan and to install it on the ground floor in an office. The only external wall available is above my desk. Can a heavy battery be installed high up on a wall? I have only ever seen them on the ground.

HotSwap

https://www.boards.ie/discussion/comment/120476758#Comment_120476758

GivEnergy make it difficult to know what the discharge rates are. All you can do is multiply the A x V’s and see what number you get. 51.2 x 80A is 4096W so this backs up the installer view. It’s not going to be more than this; but it could well be less. Even 4.1 is too low in my opinion; but then it comes down to cost.

I personally choose to avoid this manufacturer as they seem to make it difficult to determine this data point. Other manufacturers like solar edge and Huawei are totally transparent about charge and discharge rates and limitations.

HotSwap

Wall mount is fine as long as you use the correct bolts as per the manufacturer’s instructions.

bullit_dodger

https://www.boards.ie/discussion/comment/120476859#Comment_120476859

Nahh, completely well known man. I have one and I can speak with 1st hand knowledge. The 8.2kwhr battery coupled to a Gen1 inverter maxes out at 2.6Kw charge & discharge. If I had a Gen2 inverter you would be limited to 3.6Kw. Mick has a 9.5Kwh one and can speak first hand on that one and he's mentioned 3.6Kw is the discharge limt. There is however some talks on the forums about a future firmware upgrade which might allow a 4kw, but for now 3.6Kw is the limit.

Yeah, they come with a wall bracket for mounting outside.

For me a higher discharge rate wouldn't make much/any difference. Don't get me wrong, I'd LIKE a higher rate, but in reality it doesn't actually matter. Why? Well take yesterdays battery profile (which is fairly typical for me)

Battery was empty by 11pm so for the last hour or so until 12pm I was importing. A higher discharge rate would just mean I might have been empty at 10:30pm and while that would help satisfy the load earlier on.....I'd end up importing the same amount anyway. Other people though with different consumption may benifit though

I higher charge rate though - now THAT I'd really like, esp i the future where we might have short "low tariff" windows. Want to cram as much in there in 2-3 hrs.....:-)

HotSwap

https://www.boards.ie/discussion/comment/120477010#Comment_120477010

What about a 9.5 kWh battery connected to a gen 2 5kw inverter? Is that still 3.6 kw discharge rate? Or is it 5kW ?

yeah; your right; in your case you need more panels or a bigger battery more than you need a better charge discharge rate to get you off that expensive peak rate totally.

are you running a heat pump?

bullit_dodger

https://www.boards.ie/discussion/comment/120477097#Comment_120477097

I mentioned it above, but one of the regulars "Micks_address" has a 9.5Kw battery coupled to a Gen2 5Kw inverter and it's 3.6Kw charge/discharge.

Interesting side point, the 5kw limit by the way is BOTH battery and solar together. What I mean by that is if your panels are producing say 4.5Kw and your battery is fully charged, then you turn on your Trition T90 electric shower which draws 9kw, you'll satisfy 4.5Kw of that load via the panels, and then draw 0.5Kw from the battery and import the remaining 4Kw. You'd guess that it would draw 4.5kw from the panels, and then 3.6kw from the battery, but no, that 5Kw limit is on the AC output from the inverter. (It's actually about 5.3kw on my one to be exact, but who's counting)

No, no heat pump - but lots of computers including my gaming rig which has 3x monitors. That draws down a good solid 500-600watts. Fortunately I have that Energia deal from last year which had €0.079 /unit night and €0.29/day (fixed for a year) so I'm ok with drawing only a unit or two as the rest of the time I'm on night rate. But yeah, will have to knock up a DIY 15kwhr battery at some stage. Can't have more panels, already have 23 (8.8Kwp)

deezell

"....THAT I'd really like, esp in the future where we might have short "low tariff" windows. Want to cram as much in there in 2-3 hrs.....:-)"

Electric Ireland Smart meter short 2 hour low tariff. 2am to 4am, sufficient to pop 7.2kwh, 80%, back into the 9.5 battery. At 31c/unit saving, or €2.23 per topup, this works out at €8146 over the ten year life of a €5000 battery. Daytime topping from the panels are a bonus. Some supplier nights rates are as little as 13c difference, which for ten years saving of €3606 doesn't justify the battery cost alone, you're now dependent on day storage saving to justify its cost.

bullit_dodger

https://www.boards.ie/discussion/comment/120477460#Comment_120477460

Yeah, although you have to account for ~10-15% losses in battery in/out. i.e, if you put in 7.2Kwhr, you won't get out 7.2Kwhr. Still works out quite economically feasible on some tariffs and who knows what'll happen down the line. 2-3 years ago we all weren't working at home, with lights, on computers on, then Ukraine energy crisis driving prices up. etc etc

Even with a €0.10/difference your 10Kwh battery will make you €300-350/year (assuming you can cycle it everyday) - but battery not for everyone. Depends on your consumption profile and how much they are charing for it.

micks_address

Another slight benefit of the battery is to be able to have some power in the event of a power cut.. you'd think wouldn't be a big issue these times but we had 5 this winter in north county Dublin.. I'm getting a socket wired to our inverter eps in the next few weeks and going to run the router/modem from it and be able to run a few lights and maybe the TV.. (essentials obviously)

In a sense it's a ups...

mrm

https://www.boards.ie/discussion/comment/120477344#Comment_120477344

bullit_dodger, you have always stated that you are not the normal use case and your mining computer/ gaming rig requires a larger draw than most during normal operating hours, probably with a 3.6Kwh+ draw constantly draining your battery. During most times I expect most households run at say 1Kwh and it would only be at peak evening cooking time this raises to 3-4Kwh. I am limited to 2.5 discharge and this caters easily for most times through the day but I would love the larger discharge rate to cater for when the demand increases. More control of the system. Going forward I believe this may become more important than battery capacity.....of course provided your battery capacity is sufficient! I foresee those greedy providers eventually creating two peak times - morning and evening (hope they are not reading).

micks_address

https://www.boards.ie/discussion/comment/120478695#Comment_120478695

I'd say 1kwh is a high base load.. even with two working at home ours is about 600 watts, at night this drops to about 200 when we in bed.

bullit_dodger

https://www.boards.ie/discussion/comment/120478695#Comment_120478695

Might be going off the quotes point but a mining rig (depending on the config) can be as little as 100-200 watts. I've 3x of them or varying sizes. The biggest one draws down about 400w and they get turned on/off based on a custom application I wrote which interrogates the solar output and/or battery usage and uses what I have spare from generation/night rate.

Big thing for people thinking of getting quotes for batteries, is to right size it for your house. I wouldn't get too hung up on discharge/charge rates. Sure, absolutely they matter, but it's the capacity which is the important bit to get right. I've a relatively low charge rate (2.6Kw) on my battery and even though it's a relatively big battery, it was still full by 12:30pm today. Times were different back 2 years ago though, with NO fit and there was a battery grant - so the ROI was different than today.

Course as you mentioned, with those small 2-3 hr windows in the middle of the night, charge rate matters a lot with how much you can cram in there :-)

mrm

https://www.boards.ie/discussion/comment/120478704#Comment_120478704

Not really referring to base load micks_address, more the evening load before everyone heads to bed. This in our house usually involves the main TV with laptop and the second TV with PS5. I did round up but this set up is running at about 700/ 800wh. All good within the discharge rate and battery capacity covering the hours of use. Sleeping baseload is about 140-170wh. What I was referring to was those high demand times (= costly peak load times), which I would prefer to have the discharge rate increased over the 2.5 figure to give me the flexibility to control the system to my requirements. I have the opposite issue to bullit_dodger that some days I cannot utilise the battery fully before I hit the night rate due to being restricted by the discharge rate (winter time). I dont see this as a battery capacity issue, more the discharge rate, which I think is really important. If I had the higher discharge rate on offer I would go for it. The smart meter tariffs all seem to focus on short windows for night charge - so the way i see it is high charge and high discharge rates over short windows is becoming the use profile driver (night charge vs peak rate cover).

Edit: sorry I see this is the quotes thread, I will cease with this now. Was just in answer to the 9.5 vs 2no. 5.2 batteries posts.

blueskys

Just got quoted 6300 for 2.4khwp system, 6 panels with string inverter, and power diverted, including grant. Seems a bit high given new vat rate?

bullit_dodger

It occurred to me that the "formula" may need adjustment now that VAT is going/gone, however, it might remains the same (assuming prices have gone up in the last 6 months since we adjusted it and it was out of whack with reality)

Thoughts?

PCDub

https://www.boards.ie/discussion/comment/120486581#Comment_120486581

I'm getting very similar system, 2.4kwp and 6kw inverter but no diverter for 6k so thats not bad imo.

deezell

Here's what the complete materials cost for 6 panel 2.4kw nominal system, ex. vat, and without trade/installer discount, (maybe 10-15% or more). A BER is required for the grant, you may be asked to pay this yourself also. €6k quote plus €2k grant leave a lot of change for installation, about... €6k

PCDub

The BER isnt included in my quote so i'll need to factor that in but i'll be having another chat with installer this week to see if anything can be done re the cost of that and some other stuff. Currently it'll cost about 4k after the grant plus the BER. Also my quote includes a 6kw inverter.

deezell

Double check your quote is not already net of grant. I've not received a quote yet where final figure wasn't what I was expected to pay. Bigger inverter well worth an extra €500. I'd get rails for more panels later also if there was space, or you might be thinking of battery plus panels for daytime peak power inversion, requiring a hybrid or battery ready inverter.

WLB2023

Looking for any feedback on panel layout and pitch please: Have two similar priced quotes for 16 x 400W panels, all facing south and ground mounted. One quote offers 2 stacked rows of 8 panels on a metal frame with pitch of 40 degrees. The other quote offers 4 rows of 4 panels with pitch of 20 degrees (no frame). Which layout is better?

bullit_dodger

You can plug them into PVGIS and have a look yourself. I played with the figures before and there's not too much difference in slope for the year. You would however get better production in winter with 40 deg. A 20 deg slope is pretty much "end on" to the sun in Winter.

Plug 4 panels (say 1.6kw) with azimuth of 0 (south) into pvgis and then vary the slope to see the difference.

JRC Photovoltaic Geographical Information System (PVGIS) - European Commission (europa.eu)

I'd probably go with 2 stacked rows of 8 myself on 40 deg, but that's me.

HotSwap

https://www.boards.ie/discussion/comment/120487120#Comment_120487120

I assume the second system is using van Der Valk flat roof mounting racking on the ground (maybe on a bed of gravel) It’s going to take up more space and panels are low to the ground. Or maybe the plastic tubs? Prob Cheeper; but I would personally go for the racking option 40deg as your going to want to optimise for winter; and with a 20 deg angle that’s really better for summer.

Is there a Reason your doing 16 panels? Have you done any analysis to understand if this will meet your needs? Perhaps related to the planning exemption for ground mount solar pv?

DC999

https://www.boards.ie/discussion/comment/120486679#Comment_120486679

@blueskys & @PCDub 2.4kWp is a small system. I’ve a 4.9kWp and it’s all I could fit and I’d like to have more if I could. I’ve an EV so it needs 1.4kW spare excess to start to charge the car. If you’ve an EV, a 2.4kWp system won’t have the grunt to charge it – bar if there is nothing else running and it’s peak sun each day.

Any reason ye are getting such small systems? If space is the issue, I got 5 panels on the flat kitchen extension as it’s a small roof. Or you could put some on a shed roof. Or in the garden if it’s large. If it's cost, I fully understand.

For that reason, smaller systems cost more in general (and mine is one). Majority of the cost is in the labour to get to you with kit and 2 roofers & sparks. So you’re paying more than half the price of 12 panels for the 6 you’re getting.  

That said if it comes down to getting solar or not, get it - once it's the right price. Less is much better than none@blueskys