Domestic solar PV quotes 2018

air

Looks fairly standard, so you'll be clipped at 11A input current, compare that with the MPP current on your data sheet.
They're probably around 7.5A max output so it should work fine. In practice you'll never have peak output on both arrays simultaneously.
I've about 6.75kW peak (panels) myself and never saw more than 5.5kW export.

thos

Excellent, thanks for your help!

air

air wrote: »

You should put a series diode in line with both the 8 South facing ones and the 8 new ones.

Why not use opposing voltages instead?

air

Sir Liamalot wrote: »

air wrote: »

You should put a series diode in line with both the 8 South facing ones and the 8 new ones.

Why not use opposing voltages instead?

Primarily because I'm more focused on making useful practical suggestions than posting cryptic one liners.

jspuds

air wrote: »

Primarily because I'm more focused on making useful practical suggestions than posting cryptic one liners.

Please lets keep the thread on track

There's no need for series diodes in unshaded panels. As long as there is ambient light the voltage of one string will oppose the other.
Diodes reduce efficiency.

Yes and heat. Why add losses to the system? Diodes are not necessary.

air

Sir Liamalot wrote: »

There's no need for series diodes in unshaded panels. As long as there is ambient light the voltage of one string will oppose the other.
Diodes reduce efficiency.

The forward diode volt drop would cause a peak loss of efficiency of approximately 0.3% at full load in this application (assuming regular 60 cell panels) & cost next to nothing.

I think that's a fair compromise for protecting 8 panels from possible destruction in the (admittedly unlikely) event that one or all of the panels are shaded at some point in their 30 or so year installation lifetime.

A dark sheet or tarpaulin could be blown onto a string, one or more bypass diodes could fail shorted, a panel could be bypassed by cable rub etc.

There are myriad possible scenarios that are all protected against to at least some extent by a series diode.

If 0.3% is too much of an efficiency hit to live with, thos could also investigate ORing MOSFETs which have lower forward volt drop than a simple diode.

However 15A diodes are commonly available fitted to a pair of MC4 connectors which would make fitting them plug and play in this instance.

Shaded panels get destroyed now? Panels work without bypass diodes..they just reverse bias and pull down the array.

air

Sir Liamalot wrote: »

Shaded panels get destroyed now? Panels work without bypass diodes..they just reverse bias and pull down the array.

If a panel is completely shaded it produces no voltage and will be reverse biased by the other string.

It becomes a big heater and given enough time/voltage/current will be irreparably destroyed.

Why don't you try connecting a panel to a battery without a controller and leave it overnight and report back to us how well the panel operates tomorrow.

Every inverter manufacturer that I'm aware of that provides multiple parallel inputs fits diodes for this very reason.

I think I've explained the reasons sufficiently at this stage and people are free to make an educated decision either way.

niallers1

I think ye've just killed interest in this thread

Coltrane

Hoping to revive it!

I'm looking at installing more solar PV on the roof at home. My installer who seems very knowledgeable and helpful says that I won't qualify for the SEAI grant because I already have PV, even though that was not grant aided (it was installed before the current grant was introduced).

Any contrary experience? SEAI's terms and conditions state only that only one installation will be "supported" at each home, which I take to mean that they'll only grant-aid once.

unkel

Your installer is wrong. Whatever you have currently installed is irrelevant. I have PV and I got a quote for a battery only system and the grant of €1000 was applied on my quote

What's at play here is probably that the installer doesn't want to touch your current install. Which is understandable.

air

Dear Air,

I am not trying to get into a peeing competition here, I have no antipathy for you I would like to address the postings of what I consider to be contentious advice. It is nothing personal I am addressing your comments as impartial and with scientific merit. I'm happy to agree or disagree with you til the cows come home based on my own experience. Nor am I trying to divert this thread, nor reduce the tone. May I attempt to resolve the controvertial series (blocking) diode issue? We are all learning so if I may...

air wrote: »

If a panel is completely shaded it produces no voltage and will be reverse biased by the other string.

If a cell is reverse baised in a cell string it will become a heater by the other cells in that string. If a cell string is reverse biased in a panel the rest of the panels and cell strings do not heat the shaded cell string they use the bypass diodes. Limited heat, overhead built into panel. If a panel is reverse biased within a panel string it will reduce the voltage of that string by not contributing Vmp to the rest of the array using the parallel bypass diodes in the offending panel.

Easiest path to ground rules apply.

I am of course talking about pitch black, not shadow but absence of light only created by a poor siting of a panel, say under a willow tree, in a cellar etc...


If there is any diffused ambient light on the panel string it will produce Vmp at zero current and oppose current from the other string as the connected load is an easier path to ground.


In the unlikely event, a panel string is reverse-biased the lit panel string will power the load and the entirely shaded panel string as a potential divider.

Sure that's a problem, diodes aren't the solution better siting is the answer.

air wrote: »

It becomes a big heater and given enough time/voltage/current will be irreparably destroyed.

Emphasis on time (years), shading recurrence over the same cells and poor installation location choice.

air wrote: »

Why don't you try connecting a panel to a battery without a controller and leave it overnight and report back to us how well the panel operates tomorrow.

Have you tried this?


I can attest I have and it works very well.
What does a charge controller do? Reduce voltage seen at the panel to battery nominal!


If I get a 60 cell 31 Voc panel and connect it to a flooded lead acid 24V nominal meat and spuds battery with a 29.8V + temperature compensation absorption setpoint why do I need a charge controller? Opposing voltages will normalise and regulate the current. It works great, I've been doing it for years.


Now consider using a series diode in this system..
Lets say it's 1kWp on a 45A charge controller
45A x 0.7Vf = 30W peak heat devolving from that diode. I assure you the nighttime losses through the panel are less than this, and the heating effect at night is offset by the ambient temperature reduction and lack of irradiance.


Series diodes are poor practice and a high-risk failure point imo.

air wrote: »

Every inverter manufacturer that I'm aware of that provides multiple parallel inputs fits diodes for this very reason.

Is this not for isolation for more effective power point tracking?


Sure prevention of losing the array to a string failure is a rare side-benefit. I fit panel meters. If there's no output; open the offending string disconnect.

Blocking diodes are a lot like taking a 2wd off-road to me.

Here's a peer review all about it.

unkel

unkel wrote: »

What's at play here is probably that the installer doesn't want to touch your current install. Which is understandable.

I've emailed 50 installers and 4 made the short list. Either I upset them too much or vice versa.


I don't think it's understandable that some installers only want the high profit easy no questions asked jobs...


The amount of installers I've had to quote their own installation guide to is ridiculous. Quite a lot of crowbarring out there.
"Oh you can't use lead acid..."
First one to show me a B-type RCD on a high frequency inverter and a DC disconnect rated for full load rupture current gets a commendation..so far I have zero.
Hence I've designed my system for them. :rolleyes:

air

I suggest you start a new thread Sir Liam, totally OT here.

garo

It breaks my heart to see 3+kW being exported for free. As consolation I tell myself I am doing my bit for the environment.

gally74

garo wrote: »

It breaks my heart to see 3+kW being exported for free. As consolation I tell myself I am doing my bit for the environment.

Fit will come

CiaranIRE

Response for the ESB:

The smart meters upgrade programme is phased over the next 5 years. During that period services will be introduced in a phased manner beginning with “time-of-use” tariffs from 2021, with other services such as pay-as-you-go scheduled for 2023.

Initially we are focusing our meter replacement programme on 24 hour legacy meters and not day/night or pay-as-you-go meters as we don’t want customers to lose out on their current tariff or service until equivalent services are available.

We would therefore ask you at this stage to bear with us. Your meter replacement, which will be free of charge, will be scheduled at a point when Suppliers are able to offer a wider range of Smart Services.

With regard to the smart meter functionality, we confirm they do have the capability to record both import and export.

Sounds like they won't install a smart meter until they can offer the services you already have, beginning with day/night metering in 2021.

Even if a feed in tariff is announced soon, (reading between the lines) that service won't be available on the smart meter until at least after 2021 unless you install an export meter in the mean time at your own expense which likely wouldn't even pay for itself.

Hopefully they're just being a bit vague until a feed in tariff is officially announced.

Solar PV is not worth it without a FIT, no need for battery with FIT, not worth the money, sell all the excess and buy back when needed.

reklamos

[Deleted User] wrote: »

Solar PV is not worth it without a FIT, no need for battery with FIT, not worth the money, sell all the excess and buy back when needed.

FIT will only work if it is fit for purpose. We do not know the details yet but the feed to grid charge could make FIT irrelevant for most people.

unkel

It might very well be only 5c / kWh. That means with a simple no battery south facing 4kwp array producing 4MWh per year, if three quarters goes to the grid, you will get €150 per year for that (3000 * 0.05) and you save 1MWh almost completely at the day rate for self consumption, that's 1000 * 0.18 = €180 per year. So €330 per year total

Let's say this system cost you €3k installed. That means a pay back period of 9 years. Really not bad at all. Who else gets 11% return on their investment tax free?

Tax free , are you sure about that?

unkel

I would be confident that FIT income will not be taken account for income tax purposes. It would be too ridiculous to consider really. Like the free coffee you get in work.

The rest of the return is a saving you have, so not income.

antoinolachtnai

unkel wrote: »

It might very well be only 5c / kWh. That means with a simple no battery south facing 4kwp array producing 4MWh per year, if three quarters goes to the grid, you will get €150 per year for that (3000 * 0.05) and you save 1MWh almost completely at the day rate for self consumption, that's 1000 * 0.18 = €180 per year. So €330 per year total

Let's say this system cost you €3k installed. That means a pay back period of 9 years. Really not bad at all. Who else gets 11% return on their investment tax free?

5c would be a great price to get for PV. Sunnytime electricity is frequently under 3.5c wholesale. This is the time when you would be mostly exporting.

The price of sunny time electricity will fall still further when hundreds of MW of subsidised commercial PV hits the grid.

The smart meter will also give you the chance to access these cheaper prices when they are available.

So the benefit of home PV will be much smaller. On the other hand, the benefit of a home battery will be much bigger.

air

antoinolachtnai wrote: »

5c would be a great price to get for PV. Sunnytime electricity is frequently under 3.5c wholesale. This is the time when you would be mostly exporting.

The price of sunny time electricity will fall still further when hundreds of MW of subsidised commercial PV hits the grid.

The smart meter will also give you the chance to access these cheaper prices when they are available.

So the benefit of home PV will be much smaller. On the other hand, the benefit of a home battery will be much bigger.

I question your figures.
You're excluding TUOS charges again, as well as VAT.
For a long time to come, domestic PV export will be resold immediately to neighbouring properties without PV so an export rate of 5c/kWh (Inc VAT) should be profitable for energy suppliers.
Commercial PV operators are currently negotiating unsubsidised deals at well over 5c/kWh ex VAT.

unkel

antoinolachtnai wrote: »

5c would be a great price to get for PV. Sunnytime electricity is frequently under 3.5c wholesale. This is the time when you would be mostly exporting.

Even at 3.5c it probably still gives you a better return than a battery system. Or immersion diversion.

In my example above a 3.5c fit still gives a return on investment of just a touch over 10 years. Not bad. And no investments (battery / immersion diverter) and no maintenance / replacement costs

reklamos

I think Irish government being very 'innovative', will just copy/past what UK is doing. For those interested you can read it here:
https://www.ofgem.gov.uk/environmental-programmes/fit/fit-tariff-rates

In less than to months I only exported 27kWh but I do have a battery and hot water diverter.
Once FIT comes in place, for me it could make sense to cut down on water diversion and push to grid more during sunny hours.Then at night time pull back at lower cost to charge the battery at early morning hours. This way I could feed back more to the grid the next day as the batteries would be full early on and have plenty juice for evening hours. I did not do the math if that is economically viable solution when installing new setup.

antoinolachtnai

air wrote: »

I question your figures.
You're excluding TUOS charges again, as well as VAT.
For a long time to come, domestic PV export will be resold immediately to neighbouring properties without PV so an export rate of 5c/kWh (Inc VAT) should be profitable for energy suppliers.
Commercial PV operators are currently negotiating unsubsidised deals at well over 5c/kWh ex VAT.

TUoS is only a cent a kWh. You have to pay the DUoS regardless of how little of the distribution network you use. The daytime DUoS will be reduced too and peak DUoS will increase. There is already a review planned under the climate action plan to review these rates.

If you can consume all the power on site, certainly a higher price per kWh makes sense. That is why that commercial stuff works. As you rightly say, at the moment you avoid the DUoS, though that benefit will diminish as DUoS rates change.

There is also a complicated issue about de minimis benefits for small generators.

There isn’t much benefit re VAT because an unregistered person can’t offset capital cost for VAT purposes where commercial operators can. There is something that could be done with VAT on the sale but it is not going to make that much difference even if the purchasers go to the bother of implementing the VAT break.

air

antoinolachtnai wrote: »

TUoS is only a cent a kWh. You have to pay the DUoS regardless of how little of the distribution network you use. The daytime DUoS will be reduced too and peak DUoS will increase. There is already a review planned under the climate action plan to review these rates.

If you can consume all the power on site, certainly a higher price per kWh makes sense. That is why that commercial stuff works. As you rightly say, at the moment you avoid the DUoS, though that benefit will diminish as DUoS rates change.

There is also a complicated issue about de minimis benefits for small generators.

There isn’t much benefit re VAT because an unregistered person can’t offset capital cost for VAT purposes where commercial operators can. There is something that could be done with VAT on the sale but it is not going to make that much difference even if the purchasers go to the bother of implementing the VAT break.

A cent a kWh is very significant in terms of a FIT of 5c!!!

Also VAT is relevant, as the supplier is a commercial operator and can offset the VAT paid.

The advertised FIT rate is likely to be inclusive of VAT - as is the FIT on the existing (closed 9c/kWh) scheme.

A FIT of 5c/kWh Inc VAT only costs the supplier 4.4c/kWh in real terms.
Subtract the 1c/kWh saving on TUOS and it's below your claimed daytime average wholesale rate of 3.5c/kWh

I didn't mention DUOS because it's unavoidable as you say.

All told I don't see any evidence why a domestic FIT of 5c should not be perfectly commercially viable in the current market.

5c is actually quite low , they should offer night time rate minimum. That way it would cost nothing to buy back at night.

It would be a sting to get 5c and have to pay 18 c per kwh.

antoinolachtnai

air wrote: »

A cent a kWh is very significant in terms of a FIT of 5c!!!

Also VAT is relevant, as the supplier is a commercial operator and can offset the VAT paid.

The advertised FIT rate is likely to be inclusive of VAT - as is the FIT on the existing (closed 9c/kWh) scheme.

A FIT of 5c/kWh Inc VAT only costs the supplier 4.4c/kWh in real terms.
Subtract the 1c/kWh saving on TUOS and it's below your claimed daytime average wholesale rate of 3.5c/kWh

I didn't mention DUOS because it's unavoidable as you say.

All told I don't see any evidence why a domestic FIT of 5c should not be perfectly commercially viable in the current market.

What we are talking about is really more of an export tariff than a feed-in tariff.

I suppose an ex-VAT tariff of 4.4c/kWh might be possible. But it is probably realistically at the very top of what will be possible.

DUoS and access to market pricing makes a difference because if the daytime DUoS rate falls, then the savings from having the rooftop PV become smaller. This doesn't affect the price, you are quite right, but it does affect the 'base case'.

The VAT is really an open question. In the scheme you describe, the homeowner is essentially charging VAT on the electricity he/she sells. But it is hard to see how this is done legally because the householder is not VAT registered. (There is another VAT arrangement that could be used, the margin scheme, but the administration is more complex. There is a technical reason why the margin scheme cannot be used for electricity, but this could be overcome. Another way to do this is for a VAT registered person to own the panels and rent them, but this brings other VAT problems.)

Do you know what the electric ireland statement says about VAT for residential exports?

A feed-in tariff would fall outside the VAT net certainly. But that isn't really on the cards.

The PV electricity also needs to be forecast and hedged. This is important because the balancing price of electricity can go negative. Hedging costs money too.

There is an administrative and support overhead to all of this.

On the other hand there are some other money benefits (mainly to do with capacity charges) for the supplier that make this more attractive. Though these benefits are likely to get removed in coming years.

I don't mean to rain on the ol' parade, but I am being realistic about what unsubsidised residential PV will actually be worth on net when DUoS changes and when there is loads of commercial PV out there.

air

I think we're in broad agreement then that a FIT of around 5c could be implemented either on a cost neutral basis or profitably at present.
I don't think there's much point in trying to speculate too far into the future, the FIT could be reviewed regularly. DUOS could go up as easily as down if PV became very pervasive increasing daytime consumption and production.

There is no explanation of VAT treatment on the EI paperwork. The total amount of kWh export in the previous year is multiplied by .09 and the sum is credited to the customer account balance at the beginning of the following year.

Consumption and standing charges including VAT are subtracted from it until it is exhausted.

I agree VAT would need to be clarified from a consumer point of view but presumably EI have done this years ago.

unkel

air wrote: »

I think we're in broad agreement then that a FIT of around 5c could be implemented either on a cost neutral basis or profitably at present.

That's all we need. And that's all we deserve. We don't need the tax payer to subsidise people with PV. That said, we will need ever increasing penalties for all use of fossil fuels.

5 c is too low, it wouldn't make me change now in the morning if I got 5 c and had to pay 17 C peak......

Convince me otherwise......lol

unkel

Deleted User wrote: »

5 c is too low, it wouldn't make me change now in the morning if I got 5 c and had to pay 17 C peak......

Convince me otherwise......lol

Do your other investments return >10% after tax?

Mine don't, apart from my pension.

unkel

unkel wrote: »

Do your other investments return >10% after tax?

Mine don't, apart from my pension.

5 c is not a great incentive, better than nothing but not great especially at the cost to buy.

antoinolachtnai

air wrote: »

I think we're in broad agreement then that a FIT of around 5c could be implemented either on a cost neutral basis or profitably at present.
I don't think there's much point in trying to speculate too far into the future, the FIT could be reviewed regularly. DUOS could go up as easily as down if PV became very pervasive increasing daytime consumption and production.

There is no explanation of VAT treatment on the EI paperwork. The total amount of kWh export in the previous year is multiplied by .09 and the sum is credited to the customer account balance at the beginning of the following year.

Consumption and standing charges including VAT are subtracted from it until it is exhausted.

I agree VAT would need to be clarified from a consumer point of view but presumably EI have done this years ago.

Then the 9c is 9c excluding VAT.

Daytime off peak DUoS is not going to go up. It will go down bringing it into proportion with cost. Peak DUoS will certainly go up. There is no consumption driver that would make daytime consumption go up in the next five years. Maybe something would come up beyond that, but it is hard to see.

If punters don’t have certainty about the FIT it will mean the business case will be very weak, at least for non-enthusiasts.

Whatever FIT they offer they need to guarantee it for 10 years or more.

air

antoinolachtnai wrote: »

Then the 9c is 9c excluding VAT.

I don't follow your logic to be honest, but as with all your other points you are not providing any argument to support your position. Again it's getting OT.

The credit is applied against the bill after vat, not before.
If it was ex VAT it would be worth 10.22c/kWh against the total bill. It is not.

antoinolachtnai wrote: »

daytime off peak DUoS is not going to go up. It will go down bringing it into proportion with cost. Peak DUoS will certainly go up.

Your crystal ball is mighty impressive. Can you elaborate?

The DUOS charges are surely paid by the consumer of the export in any case which makes them moot for the purposes of this discussion.

Are they are paid at export and again import for generation direct into distribution?
I have no idea but that sounds like double charging to me if it is the case.

antoinolachtnai wrote: »

There is no consumption driver that would make daytime consumption go up in the next five years. Maybe something would come up beyond that, but it is hard to see.

I'm not so sure. Data centres are showing huge growth and are 24/7. Dynamic consumer pricing (with the imminent smart meter rollout) has potential to radically alter consumption patterns. Increased adoption of EVs and PV, not to mention increased carbon pricing can also have an effect. If people are driving EVs to work and charging them during the day that can provide consumption to be met by domestic PV export.

antoinolachtnai wrote: »

If punters don’t have certainty about the FIT it will mean the business case will be very weak, at least for non-enthusiasts.

I agree and that certainty could be offered by the government at very low marginal cost by guaranteeing a fixed rate. At the price levels we are discussing here the cost should be negligible, especially at current PV penetration levels.

PV generated daytime electricity should continue to be very competitive vs the alternatives in the foreseeable future. I don't see what other zero carbon sources that are going to be competitive on a calm summers day where wind output is low for example.

gally74

Hello,

So I'm 3 months in,

1.23MWh produced, 1.06 MWh consumed - 86% 4.2 system

We were away a lot during August, so I expect to go 90% plus for the rest of the year.

Overall v happy,

Charlie-Bravo

^ what's your setup and orientation?

wexfordman2

astrofluff wrote: »

^ what's your setup and orientation?

6kw and straight :-)

Charlie-Bravo

Lolz, have you got a battery setup and facing straight south?!

ch750536

Jumping on the back of this. Was heading for a 6k battery system but based on whats happening in the market would it make more sense to go with a 9k non battery system (straight south)?

ch750536

ch750536 wrote: »

Jumping on the back of this. Was heading for a 6k battery system but based on whats happening in the market would it make more sense to go with a 9k non battery system (straight south)?

Why would you got with a 9 Kwp array when you can only send 5.5 Kw to the grid on single phase ?

You'll generate for more than you can use in the brighter months and it will all go to the grid for free, a battery won't be large enough to store all the excess and you'll struggle to fill it in winter.

A hybrid system of wind and solar PV would be better, in my opinion .

reklamos

ch750536 wrote: »

Jumping on the back of this. Was heading for a 6k battery system but based on whats happening in the market would it make more sense to go with a 9k non battery system (straight south)?

That really depends on your usage pattern, power of the whole system and if you have hot water diverter. I have 4.5 system south facing with 7 battery and diverter. In July and August I have exported 27kWh. So it is not a lot and the numbers will be going down from now on. Without diverter, 9kWh battery should be fine.

Battery makes a big cost of the whole system and you will not get bigger SEAI grant(if you looking for one) by getting bigger battery.

I would only get bigger battery, if I can get it cheap. You can always add battery later and hopefully with time prices will come down.

Size the system to your needs, no point dumping energy you wouldn't other wise use, that's a waste .

This is the greatest issue with Solar PV that and the fact you got most energy production in Summer when you could otherwise use it to run a heatpump.

air

[Deleted User] wrote: »

Why would you got with a 9 Kwp array when you can only send 5.5 Kw to the grid on single phase ?

It makes perfect sense as the amount of time the array will spend outputting between 5.5 and 9kW will be minimal. Furthermore it's likely to occur at the time of year when you have more PV energy available than you can use anyway.

[Deleted User] wrote: »

A hybrid system of wind and solar PV would be better, in my opinion .

Wind makes very little sense unless you are off grid and even then it's very expensive energy.
It's a hobby in itself keeping them maintained and maintenance is not straightforward.
Furthermore very very few properties have suitable sites for it.

I manage 6 small wind installations and the best one produces 3 times more than the worst despite identical hub heights.

It's great to have opinions but if you're offering advice to other people it's better if you only offer ones which are based on facts or experience IMHO.

air

air wrote: »

It makes perfect sense as the amount of time the array will spend outputting between 5.5 and 9kW will be minimal. Furthermore it's likely to occur at the time of year when you have more PV energy available than you can use anyway.


It's great to have opinions but if you're offering advice to other people it's better if you only offer ones which are based on facts or experience IMHO.

Yeah so you advise people to dump energy then ? that's fantastic advice.

Hey everyone, air says it's better to buy loads of Solar PV to dump it.

Yep , pay money to dump energy, great advice !