Domestic solar PV quotes 2018

Scottie99

I’ve noted through this thread that people are getting different sizes of systems, I’m not sure what size would suit my needs. I know an installer would survey then recommend, but I’d like to get info from other experienced folks on here.

We’ve a four bed detached house (Meath), roughly 1500sq. (4 persons)
Our annual electricity bill is roughly €1560 (€260 bimonthly)
We’ve a night meter, roughly 35/40% usage.
I’ve an EV doing 26/28K a year.

What size of system/battery others do you recommend?
What monthly/annual savings do you think the system could save me.
Obviously a rough cost after Government Grants.

Many thanks.

air

Scottie99 wrote: »

I’ve noted through this thread that people are getting different sizes of systems, I’m not sure what size would suit my needs. I know an installer would survey then recommend, but I’d like to get info from other experienced folks on here.

We’ve a four bed detached house (Meath), roughly 1500sq. (4 persons)
Our annual electricity bill is roughly €1560 (€260 bimonthly)
We’ve a night meter, roughly 35/40% usage.
I’ve an EV doing 26/28K a year.

What size of system/battery others do you recommend?
What monthly/annual savings do you think the system could save me.
Obviously a rough cost after Government Grants.

Many thanks.

Your daytime usage is pretty large, do you do a lot of EV charging during the day? A few energy saving initiatives would be the first port of call before you add PV.

wexfordman2

H.E. Pennypacker wrote: »

They'll probably tell you the same thing that they told me - they can't discuss any details about contractors for data protection reasons and that the grant is only payable when the work is done by contractors that are on their approved list. I don't think that the last point is a big deal as once the contractor is tax compliant and uses properly qualified labour then there shouldn't be an issue getting on to the list.

Your array looks fantastic BTW

Just got word from the installers the seai checklist is out, so they should be scheduling my install soon, will be calling me tomorrow :-)

Shefwedfan

Scottie99 wrote: »

I’ve noted through this thread that people are getting different sizes of systems, I’m not sure what size would suit my needs. I know an installer would survey then recommend, but I’d like to get info from other experienced folks on here.

We’ve a four bed detached house (Meath), roughly 1500sq. (4 persons)
Our annual electricity bill is roughly €1560 (€260 bimonthly)
We’ve a night meter, roughly 35/40% usage.
I’ve an EV doing 26/28K a year.

What size of system/battery others do you recommend?
What monthly/annual savings do you think the system could save me.
Obviously a rough cost after Government Grants.

Many thanks.

Why the majority of the electricity on day rate?



b

uck51js9zml2yt

wexfordman2 wrote: »

Just got word from the installers the seai checklist is out, so they should be scheduling my install soon, will be calling me tomorrow :-)

That's good news. I should be hearing from him soon. Will be interested to see what he comes back with.

Scottie99

Shefwedfan wrote: »

Why the majority of the electricity on day rate?



b

Actually, I’m wrong there. Instead of usage I put cost as a percentage - apologies

niallers1

Hi Scottie99, 
Your bi-monthly bill is at least twice what mine is for similiar family size. A bit off topic but have you looked at reducing your usage i.e not leaving appliances on standby oven, tv, microwave, radio, satelite box e.t.c. , turning off lights when not using a room, You should also change to LED lightbulbs. They use hardly any electricity and last years longer .
I went for a 4.2kw with 4.8kw battery. I have it in about 7 weeks now and think it's great. I don't expect to get much out of it in Nov/Dec/Jan but for the rest of the year it will cover most of my electricty needs.
in 7 weeks I've generated 362kwh ( October was 192kwh)

uck51js9zml2yt

My quote

14 x Solar PV Modules/Panels 325w
1 x 3.6kw Hybrid Inverters
3 x 2kw Hybrid Batteries
1 x Eddi
1 x Emergency Isolation
1 x BER Assessment
1 x Warranty

€11918
Less € 3800 grant.

Wexford ..how does it compare with yours?

Edit: I see you have an extra 4 panels and a bigger inverter for the same money !!
Quoted me an extra 1500(ex vat) for the bigger inverter and 4 extra panels.

unkel

Rip-off.

uck51js9zml2yt

unkel wrote: »

Rip-off.

Seems like it!!!

I was talking to a local man this evening. He's giving me a price.

unkel

You are aware that the installer has to be on the SEAI approved Solar PV installer list four you to get the subsidies though?

That said, there's a lot to say for doing a DIY install (or with your local man) and with an electrician hooking it up for you and forgetting about the subsidies...

Scottie99

niallers1 wrote: »

Hi Scottie99, 
Your bi-monthly bill is at least twice what mine is for similiar family size. A bit off topic but have you looked at reducing your usage i.e not leaving appliances on standby oven, tv, microwave, radio, satelite box e.t.c. , turning off lights when not using a room, You should also change out LED lightbulbs. They use hardly any electricity and last years longer .
I went for a 4kw with 4.8kw battery. I have it in about 7 weeks now and think it's great. I don't expect to get much out of it in Nov/Dec/Jan but for the rest of the year it will cover most of my electricty needs.
in 7 weeks I've generated 362kwh ( October was 192kwh)

I’m seeing the average running cost in Ireland for a 3/4 bed house is €224 bimonthly. I’m also running a car 4000km bimonthly, I think I’m doing ok.
The whole house has low energy bulbs, yes there are small saving to be made but I can’t see much.

http://www.moneyguideireland.com/much-average-electricity-bill.html

uck51js9zml2yt

unkel wrote: »

You are aware that the installer has to be on the SEAI approved Solar PV installer list four you to get the subsidies though?

That said, there's a lot to say for doing a DIY install (or with your local man) and with an electrician hooking it up for you and forgetting about the subsidies...

When I said local, it was an approved company whose owner happens to be located less than 5 minutes from my house.

unkel

Keep us updated tatranska!

uck51js9zml2yt

unkel wrote: »

Keep us updated tatranska!

I'll be talking to the others about the price difference between me and Wexford man.
They'd want some good excuse for the difference in price !

wexfordman2

Brecken Tart Newscast wrote: »

I'll be talking to the others about the price difference between me and Wexford man.
They'd want some good excuse for the difference in price !

Is it the same supplier as mine?

uck51js9zml2yt

wexfordman2 wrote: »

Is it the same supplier as mine?

Yes. It's the company you told me about!

gunnerfitzy

Brecken Tart Newscast wrote: »

My quote

14 x Solar PV Modules/Panels 325w
1 x 3.6kw Hybrid Inverters
3 x 2kw Hybrid Batteries
1 x Eddi
1 x Emergency Isolation
1 x BER Assessment
1 x Warranty

€11918
Less € 3800 grant.

Wexford ..how does it compare with yours?

Edit: I see you have an extra 4 panels and a bigger inverter for the same money !!
Quoted me an extra 1500(ex vat) for the bigger inverter and 4 extra panels.

Is there not a difference in battery configurations? I think Wexfordman2 is getting 2 x 2.5kWh batteries. Only 1 kWh in the difference I know but still a different configuration and possibly manufacturer. Also, I think Wexfordman2 played hardball and squeezed a further reduction in the quote first mentioned.

wexfordman2

gunnerfitzy wrote: »

Is there not a difference in battery configurations? I think Wexfordman2 is getting 2 x 2.5kWh batteries. Only 1 kWh in the difference I know but still a different configuration and possibly manufacturer. Also, I think Wexfordman2 played hardball and squeezed a further reduction in the quote first mentioned.

The inverter is smaller as well, mine is/will be a 5kw inverter. Double check it is the right size , itcould be a typing error.

unkel

It is plain stupid that tatranska got a quote for a battery system with 4.6kwp and just a 3.6kW hybrid inverter. Do these installers take us for fools or are they just completely incompetent?

What if your solar array produces maximum power and your battery is full and your house draws say 5kW? With the suggested setup you will use 3.6kW from the panels (that's all the inverter can give you), send 1kW to the grid for free and at the same time import and pay for 1.4kW from the grid :rolleyes:

With a 5kW hybrid inverter you send nothing for free to the grid and there is no need to import and pay for anything from the grid either...

KCross

unkel wrote: »

It is plain stupid that tatranska got a quote for a battery system with 4.6kwp and just a 3.6kW hybrid inverter. Do these installers take us for fools or are they just completely incompetent?

What if your solar array produces maximum power and your battery is full and your house draws say 5kW? With the suggested setup you will use 3.6kW from the panels (that's all the inverter can give you), send 1kW to the grid for free and at the same time import and pay for 1.4kW from the grid :rolleyes:

With a 5kW hybrid inverter you send nothing for free to the grid and there is no need to import and pay for anything from the grid either...

I dont think its that simple.
If you size the inverter too high you lose more when the production is low... is my understanding.

So, iirc, its better to size the inverter slightly less than the kWp to improve efficiency. Now, if you had medium term plans to add more panels it would make sense to get a larger inverter up front and just pay for install once.

conor_mc

Wexfordman2, would you mind pm’ing me your supplier please? Appreciate it!

unkel

KCross wrote: »

I dont think its that simple.
If you size the inverter too high you lose more when the production is low... is my understanding..

Nah. That's mostly from the past. Inverter are only marginally less efficient these
days anyway when not fully loaded

Hybrid inverters in a battery attached solar PV system need to be of higher power than the max of the solar array. It is plain ridiculous to be having to give electricity to the grid back for free while your battery is full and you have to buy electricity from the grid at the higher rate at the same time.

randombar

Hi All,

I've herself sold on this. I just need to sell it to myself a bit more.

It would be useful to know the price of the bee cert if people had it as some are quoting with and others without.

Is there somewhere you can calculate daily average return per month per panel or something.

Adding a battery in and calculating size v cost, working out what that will do for your demand. I.e. you charge it up during the day. Everyone gets home and uses it in the evening. Should you charge up again on night saver over night and use in morning?

I'm averaging 8.69 units per day and 2.92 units per night

Is the eddi worth it if you have solar thermal already (I doubt it)

A few quotes aren't including the essential load wiring. I'm guessing any electrician can do this. Is it a day's work? An idea of costs? Many additional parts required?

Thanks,
Gary

P.S. bargain alerts will have cost me a fraction of what this thread is going to ðŸ˜

air

unkel wrote: »

With the suggested setup you will use 3.6kW from the panels (that's all the inverter can give you), send 1kW to the grid for free and at the same time import and pay for 1.4kW from the grid :rolleyes:

Your assertion here that it is possible to simultaneously import and export to the grid just highlights that you have little to no understanding of the subject at hand.
It might be better to hold off on the advice until you pick up some basic knowledge and understanding of the area so you don't mislead other people further.

In the situation outlined, (5kw production, 5kW load, 3.6kW inverter) the PV will provide 3.6kW to the load via the inverter and the remainder of 1.4kW will be imported from the grid.

On the inverter sizing, it always has been and remains, good practice to undersize the inverter.

Every inverter has a minimum base load for operation and this is proportional to it's maximum output capacity. The bigger the inverter the lower the part load efficiency will be in general terms.
Granted it's normally undersized by slightly less than in this instance.
With a 5kW array the number of hours in the year
(in Ireland) that production will be between 3.6kW and 5kW is quite limited.
As a result the clipping of total energy production is not hugely significant. Furthermore any clipping is likely to occur in mid summer when production is likely to be exceeding both consumption and battery storage capacity. With zero FIT that missed portion is usually worthless.

With an array of 5kW it is even more likely than normal to be split over 2 strings facing different directions which only serves to reduce peak production further.
A multi directional array is generally desirable as it helps increase self consumption by extending the production day in a zero FIT environment such as currently exists.

Finally a 5kW inverter may well require a larger battery bank than a 3.6kW one depending on the charge and discharge capability of the battery selected if it is to be able to charge and discharge at 5kW.

The marginal cost of the bigger battery in addition to the uplift for the 3.6kW to 5kW inverter is likely to have a payback of many decades since there is no grant aid for this element.

antoinolachtnai

This is slightly off-topic but is it possible to get these hybrid inverters to discharge towards the grid, i.e., discharge even if there is little or no loadinside the home? How is that done? (This would be importanr if you eanted to use these units to balance the grid.)

KCross

air wrote: »

On the inverter sizing, it always has been and remains, good practice to undersize the inverter.

Every inverter has a minimum base load for operation and this is proportional to it's maximum output capacity. The bigger the inverter the lower the part load efficiency will be in general terms.

That was exactly what I understood too.

Do you have qualificatons yourself in the SolarPV area?

air wrote: »

Granted it's normally undersized by slightly less than in this instance.
With a 5kW array the number of hours in the year
(in Ireland) that production will be between 3.6kW and 5kW is quite limited.

Indeed. I think the bit unkel is missing is that you dont decide to put in 5kWp vs 4kWp to get 5kW from the panels. The extra panels in that case is to boost your overall generation at the lower end, not to try to achieve 5kW.

As you said, the lost/clipped 1kW is going to be rare, particularly if you have battery storage.

How often would you really have a battery full AND 5kW being generated AND then need 5kW of continuous load at that exact time. Thats going to be an insignificant amount of time. It would require something like an EV to suck up that level of power and the EV would need to be at home.

If it was possible to get a 5kW inverter at the same cost and same efficiency as a 3kW inverter then of course you would buy it but clearly thats not the case. There is a cost.

air wrote: »

With an array of 5kW it is even more likely than normal to be split over 2 strings facing different directions which only serves to reduce peak production further.
A multi directional array is generally desirable as it helps increase self consumption by extending the production day in a zero FIT environment such as currently exists.

This is exactly what I'm considering myself and what I asked for in my quotes.

I dont want all the panels south facing and then giving me little generation in the evening, so I'm planning to split it into two orientations so that I get a decent generation right up until sun down. An even smaller inverter is required in that case depending on how you split the panels.

KCross

GaryCocs wrote: »

Hi All,

I've herself sold on this. I just need to sell it to myself a bit more.

It would be useful to know the price of the bee cert if people had it as some are quoting with and others without.

Is there somewhere you can calculate daily average return per month per panel or something.

Adding a battery in and calculating size v cost, working out what that will do for your demand. I.e. you charge it up during the day. Everyone gets home and uses it in the evening. Should you charge up again on night saver over night and use in morning?

I'm averaging 8.69 units per day and 2.92 units per night

Is the eddi worth it if you have solar thermal already (I doubt it)

A few quotes aren't including the essential load wiring. I'm guessing any electrician can do this. Is it a day's work? An idea of costs? Many additional parts required?

Thanks,
Gary

P.S. bargain alerts will have cost me a fraction of what this thread is going to ðŸ˜

From analysis of my own consumption a battery makes no financial sense and I'm a high user of electicity.

The payback is, imo, 15yrs+
Thats just too long to be a sensible buy.

The quotes you get will talk about 7yr paybacks but they are generally rubbish claims as they use standard rate electricity for the calculations and they assume 100% utilisation of the energy by diverting to hot water which is skewing their figures to make it look better than it is.

The figure you should be using to calculate your payback should be the night rate of 8c/kWh unless the battery is displacing something that cant be moved to night rate (background load, cooking etc). And when calculating the day rate it should use the discounted rate that everyone can avail of which is around 17c/kWh right now, not the 20-22kWh that the SolarPV providers use in their calculations..... add it all up and the payback will be 15yrs+, not 7.... at least thats what fell out the bottom of my spreadsheet anyway.... YMMV.

By the time it has just paid for itself it will be very old tech, degraded and you are then crossing all your fingers that it will last another 10yrs to give you a payback. If anything goes wrong like a failed inverter (which does happen) your TCO is completely shot. It just doesnt make sense, imo. The payback needs to be <10yrs, preferably 5 to make it a sensible investment.


There is also the distinct possibility that there will be a Feed-in-tariff in the next 10yrs which will cost ALOT less than battery tech and is much more usable and scalable and you're not worrying about battery degradation etc. If you have stumped up for a battery and then a FiT comes in you will have wasted your investment, imo.

I know others on here believe in drawing the grant. I think its foolhardy. Decide for yourself but definitely run the numbers for your house and see what you get.

air

antoinolachtnai wrote: »

This is slightly off-topic but is it possible to get these hybrid inverters to discharge towards the grid, i.e., discharge even if there is little or no loadinside the home? How is that done? (This would be importanr if you eanted to use these units to balance the grid.)

It would just require a software change to trigger export when required and set up limits on charge and discharge levels. Discharging to the grid is no different to the home as far as the output stage of the inverter is concerned.

wexfordman2

KCross wrote: »

From analysis of my own consumption a battery makes no financial sense and I'm a high user of electicity.

The payback is, imo, 15yrs+
Thats just too long to be a sensible buy.

The quotes you get will talk about 7yr paybacks but they are generally rubbish claims as they use standard rate electricity for the calculations and they assume 100% utilisation of the energy by diverting to hot water which is skewing their figures to make it look better than it is.

The figure you should be using to calculate your payback should be the night rate of 8c/kWh unless the battery is displacing something that cant be moved to night rate (background load, cooking etc). And when calculating the day rate it should use the discounted rate that everyone can avail of which is around 17c/kWh right now, not the 20-22kWh that the SolarPV providers use in their calculations..... add it all up and the payback will be 15yrs+, not 7.... at least thats what fell out the bottom of my spreadsheet anyway.... YMMV.

By the time it has just paid for itself it will be very old tech, degraded and you are then crossing all your fingers that it will last another 10yrs to give you a payback. If anything goes wrong like a failed inverter (which does happen) your TCO is completely shot. It just doesnt make sense, imo. The payback needs to be <10yrs, preferably 5 to make it a sensible investment.


There is also the distinct possibility that there will be a Feed-in-tariff in the next 10yrs which will cost ALOT less than battery tech and is much more usable and scalable and you're not worrying about battery degradation etc. If you have stumped up for a battery and then a FiT comes in you will have wasted your investment, imo.

I know others on here believe in drawing the grant. I think its foolhardy. Decide for yourself but definitely run the numbers for your house and see what you get.

The only thing is, the way the front works, is if you want a 4kwp system the grant requires the battery, so if the battery costs you 5k, the actual cost to you is 2,600 idlf you discount the additional 2,400 in grant money you will get.

KCross

wexfordman2 wrote: »

The only thing is, the way the front works, is if you want a 4kwp system the grant requires the battery, so if the battery costs you 5k, the actual cost to you is 2,600 idlf you discount the additional 2,400 in grant money you will get.

You are correct, thats how the grant system works. The payback is very long (15yrs+) even with the grant.

Prior to the grant it was even longer, obviously.

randombar

KCross wrote: »

From analysis of my own consumption a battery makes no financial sense and I'm a high user of electicity.

The payback is, imo, 15yrs+
Thats just too long to be a sensible buy.

The quotes you get will talk about 7yr paybacks but they are generally rubbish claims as they use standard rate electricity for the calculations and they assume 100% utilisation of the energy by diverting to hot water which is skewing their figures to make it look better than it is.

The figure you should be using to calculate your payback should be the night rate of 8c/kWh unless the battery is displacing something that cant be moved to night rate (background load, cooking etc). And when calculating the day rate it should use the discounted rate that everyone can avail of which is around 17c/kWh right now, not the 20-22kWh that the SolarPV providers use in their calculations..... add it all up and the payback will be 15yrs+, not 7.... at least thats what fell out the bottom of my spreadsheet anyway.... YMMV.

By the time it has just paid for itself it will be very old tech, degraded and you are then crossing all your fingers that it will last another 10yrs to give you a payback. If anything goes wrong like a failed inverter (which does happen) your TCO is completely shot. It just doesnt make sense, imo. The payback needs to be <10yrs, preferably 5 to make it a sensible investment.


There is also the distinct possibility that there will be a Feed-in-tariff in the next 10yrs which will cost ALOT less than battery tech and is much more usable and scalable and you're not worrying about battery degradation etc. If you have stumped up for a battery and then a FiT comes in you will have wasted your investment, imo.

I know others on here believe in drawing the grant. I think its foolhardy. Decide for yourself but definitely run the numbers for your house and see what you get.

Could you send on the spreadsheet you used to calculate ROI? Think I've to do a few more sums.

I did receive a quote with and without a 2.4kwh battery and it was only 1300 + vat (not including labour) difference.

wexfordman2

KCross wrote: »

You are correct, thats how the grant system works. The payback is very long (15yrs+) even with the grant.

Prior to the grant it was even longer, obviously.

Can't see it taking 15yrs. If you take even an assumption without pv and just using it as a night save device.

Charge battery overnight, 5kwh at 8c per kwh, is 40c

Discharge during the day, at 18c per kwh, and you save 50c per day, 3.50 per week or 182 euro per year, which is approx 15 year payback.

That's without solar pv being used to charge the battery.

KCross

wexfordman2 wrote: »

Can't see it taking 15yrs. If you take even an assumption without pv and just using it as a night save device.

Charge battery overnight, 5kwh at 8c per kwh, is 40c

Discharge during the day, at 18c per kwh, and you save 50c per day, 3.50 per week or 182 euro per year, which is approx 15 year payback.

That's without solar pv being used to charge the battery.

You're assuming that you will be able to fully charge and discharge the battery every day of the year which is a gross over-estimation/simplification.

A 4kWp system today in Ireland would have generated less than 2kWh and most likely all of that would have been used by the house background load and nothing to the battery.

How are you then going to manage the system to tell it to be a night saver device tonight but be an excess storage device tomorrow.... you'd need to be sitting on weather forcecasts and second guessing your generation continuously.... its not a viable way, imo, to use the system. It needs to be plug 'n play. Unless you have found an inverter with some super smart controls that I havent seen.

If you have run the numbers for your own house and you are confident it works for you then great, I wish you the best with it. I just dont see it myself and I based my calculations on real world weekly figures from Solar PV systems installed in Ireland (they are publicly available stats) and I modelled it on a monthly basis with my house consumption along with the quotes I got.... it just didnt stack up and certainly didnt give anywhere near the payback time I was comfortable with. Even if my figures were out 20% it was still too long a payback.

SolarPV on its own (no battery) just about makes sense but I'm trying to do a more direct labour route to reduce the ROI time further.... not sure yet if it will work out since you have to forego the grant in this scenario..... still working on it though, just need a spark now that I can trust and willing to do it.

wexfordman2

KCross wrote: »

You're assuming that you will be able to fully charge and discharge the battery every day of the year which is a gross over-estimation/simplification.

A 4kWp system today in Ireland would have generated less than 2kWh and most likely all of that would have been used by the house background load and nothing to the battery.

How are you then going to manage the system to tell it to be a night saver device tonight but be an excess storage device tomorrow.... you'd need to be sitting on weather forcecasts and second guessing your generation continuously.... its not a viable way, imo, to use the system. It needs to be plug 'n play. Unless you have found an inverter with some super smart controls that I havent seen.

If you have run the numbers for your own house and you are confident it works for you then great, I wish you the best with it. I just dont see it myself and I based my calculations on real world weekly figures from Solar PV systems installed in Ireland (they are publicly available stats) and I modelled it on a monthly basis with my house consumption along with the quotes I got.... it just didnt stack up and certainly didnt give anywhere near the payback time I was comfortable with. Even if my figures were out 20% it was still too long a payback.

SolarPV on its own (no battery) just about makes sense but I'm trying to do a more direct labour route to reduce the ROI time further.... not sure yet if it will work out since you have to forego the grant in this scenario..... still working on it though, just need a spark now that I can trust and willing to do it.

The figures i have though were based on not using and solar pv, just charging during night to avail of low rate. What I was trying to show was that even the battery in it's own, at 2,600 would take less than the 15yrs payback you mentioned.


As far as telling the system when to charge, i would think the smarts are not too much of a challenge.

I mean, you charge it by the cheapest rate electricity available to you.

A) excess solar
night rate

uck51js9zml2yt

wexfordman2 wrote: »

The figures i have though were based on not using and solar pv, just charging during night to avail of low rate. What I was trying to show was that even the battery in it's own, at 2,600 would take less than the 15yrs payback you mentioned.


As far as telling the system when to charge, i would think the smarts are not too much of a challenge.

I mean, you charge it by the cheapest rate electricity available to you.

A) excess solar
night rate

Is that what you've done?

wexfordman2

Brecken Tart Newscast wrote: »

Is that what you've done?

Install not finished yet, but I have night rate and the system will be tuned to utilise night rate and solar.

uck51js9zml2yt

wexfordman2 wrote: »

Install not finished yet, but I have night rate and the system will be tuned to utilise night rate and solar.

Are they doing this for you? Is it in the price you quoted?

KCross

wexfordman2 wrote: »

The figures i have though were based on not using and solar pv, just charging during night to avail of low rate. What I was trying to show was that even the battery in it's own, at 2,600 would take less than the 15yrs payback you mentioned.

Yea, I understood your point. I'm pointing out that you wont get a full charge/discharge cycle every day with SolarPV, so your example doesnt really tell you anything.

wexfordman2 wrote: »

As far as telling the system when to charge, i would think the smarts are not too much of a challenge.

I mean, you charge it by the cheapest rate electricity available to you.

A) excess solar
night rate

Maybe not that much of a challenge if the inverter is connected to the net and is reading forecasts or something but the reality is that the inverters, AFAIK, dont do anything like that.

So, the reality is you would have to do the following each day...

- check forecast for tomorrow
- decide if there will be excess generation from your system or not.
- calculate if that excess is enough to justify not charging the battery on night saver or maybe only half or quarter charging it etc.
- Make the necessary changes to the system (if it even allows you to) for the next day.
- repeat each day.

Its not viable really to do it manually. It would have to be automated.
If you are aware of an inverter that has that capability I'd like to hear about it and I'll recalculate myself.


I believe the system will be setup to behave in one particular way and thats it. You wont get a full charge/discharge cycle out of it 365 days and thats the key point.

_dof_

KCross wrote: »

How are you then going to manage the system to tell it to be a night saver device tonight but be an excess storage device tomorrow.... you'd need to be sitting on weather forcecasts and second guessing your generation continuously.... its not a viable way, imo, to use the system. It needs to be plug 'n play. Unless you have found an inverter with some super smart controls that I havent seen.

I think the Moixa does just that, looks like some pretty cool tech. Don't know if it's available in Ireland though.

KCross

_dof_ wrote: »

I think the Moixa does just that, looks like some pretty cool tech. Don't know if it's available in Ireland though.

Thanks, that says it takes weather input...

We’ll explain the “SMART” element of our solar energy service. Using machine learning, it utilises inputs from the weather and your energy usage patterns to create an optimal plan for your battery.

However I dont think its in realtime or at least I cant see that from their website. Its something that is calculated by them and they advise you how to configure the system. Its still "hardcoded".

I might fire them an email and confirm.

And as you said, doesnt look like its in Ireland anyway.

unkel

air wrote: »

Your assertion here that it is possible to simultaneously import and export to the grid just highlights that you have little to no understanding of the subject at hand.

Reading back what I posted about importing and exporting at the same time and indeed it makes no sense. I apologise

air wrote: »

In the situation outlined, (5kw production, 5kW load, 3.6kW inverter) the PV will provide 3.6kW to the load via the inverter and the remainder of 1.4kW will be imported from the grid.

My main point was not about sizing of an inverter in a PV system, I agree with your points. It is more about the sizing of a hybrid inverter in a PV + battery system. It makes no sense to me that you have to import from the grid at the high day rate while your battery is full

I maintain my position that a hybrid inverter of 3.6kW is too small for a 5kwp array + 6kWh battery

unkel

KCross wrote: »

If it was possible to get a 5kW inverter at the same cost and same efficiency as a 3kW inverter then of course you would buy it but clearly thats not the case. There is a cost.

3.6kW Solis hybrid inverter €1258 + VAT
5.0kW Solis hybrid inverter €1298 + VAT

air

unkel wrote: »

Reading back what I posted about importing and exporting at the same time and indeed it makes no sense. I apologise

No problem, we all make mistakes.

unkel wrote: »

It makes no sense to me that you have to import from the grid at the high day rate while your battery is full

This is only relevant at times when the battery has available capacity and power demand is between 3.6kW and 5kW, in reality this will be a tiny percentage of operating time for the vast majority of households.

unkel wrote: »

I maintain my position that a hybrid inverter of 3.6kW is too small for a 5kwp array + 6kWh battery

That's a reasonable position, but it would be of more value if you justified it with some reasoning.

The negligible cost difference you have listed goes a long way towards justifying the larger inverter especially if the purchaser has a mind to expand the PV array down the line.

Regarding the system in question, a single 2kWh module is the way to go at present. Add the additional modules at a later date when the cost has reduced further as there is no grant aid towards them and the expansion should be plug and play.

_dof_

KCross wrote: »

Thanks, that says it takes weather input...

We’ll explain the “SMART” element of our solar energy service. Using machine learning, it utilises inputs from the weather and your energy usage patterns to create an optimal plan for your battery.

However I dont think its in realtime or at least I cant see that from their website. Its something that is calculated by them and they advise you how to configure the system. Its still "hardcoded".

I might fire them an email and confirm.

And as you said, doesnt look like its in Ireland anyway.

I had heard the CEO of Moixa discussing it in an interview and my understanding was that it was all automatic, the smart controller learned your usage patterns and took the weather forecast and your usage patterns into account to automatically adjust the charging and of the battery to maximize usage of the PV and minimize import of the grid at high rate and minimize the export to the grid (assuming no FIT).

So, if it knew that it would be cloudy tomorrow and had learned that your PV installation would only generate a small amount, it would charge the battery from the grid overnight to nearly full, but if it was forecast to be sunny tomorrow and your usage pattern showed that the PV wouldn't cover the first couple of hours of demand, then the battery would be charged just enough overnight to cover that shortfall, based on the prediction that the PV would generate enough to cover the house demand and charge the battery for the rest of the day.

But I could be wrong. If you get more details from them, please do share.

unkel

air wrote: »

The negligible cost difference you have listed goes a long way towards justifying the larger inverter especially if the purchaser has a mind to expand the PV array down the line.

This is it. This thread is mainly about PV installs based on the new subsidy. Which is capped at 4kwp

Anyone putting up a €10k system (before subsidies) is fairly sure they are going to stay in their house for a very long time. And we all will be using a lot more electricity in future (and less fossil fuels). Panels are already very cheap and it is super easy to add a few panels to an existing system. Plug and play. I sure would plan to add more panels myself later if I had a subsidised system like that installed today.

It makes no sense at all to install a 3.6kW hybrid inverter in a system like that (when a 5kW inverter costs the same)

wexfordman2

Brecken Tart Newscast wrote: »

Are they doing this for you? Is it in the price you quoted?

Sorry, I think you got the wrong end of the stick, I was talking about a hypothetical cost of 5k for a battery only

wexfordman2

KCross wrote: »

Yea, I understood your point. I'm pointing out that you wont get a full charge/discharge cycle every day with SolarPV, so your example doesnt really tell you anything.




Maybe not that much of a challenge if the inverter is connected to the net and is reading forecasts or something but the reality is that the inverters, AFAIK, dont do anything like that.

So, the reality is you would have to do the following each day...

- check forecast for tomorrow
- decide if there will be excess generation from your system or not.
- calculate if that excess is enough to justify not charging the battery on night saver or maybe only half or quarter charging it etc.
- Make the necessary changes to the system (if it even allows you to) for the next day.
- repeat each day.

Its not viable really to do it manually. It would have to be automated.
If you are aware of an inverter that has that capability I'd like to hear about it and I'll recalculate myself.


I believe the system will be setup to behave in one particular way and thats it. You wont get a full charge/discharge cycle out of it 365 days and thats the key point.

Sorry kc, but you are.missing the point.


Fristly, you referred to a 15yr payback in a solar with battery, I queried that showing a payback of 15yrs for a battery system that is purely for night rate charging.

So my point was, that if there is a 15yr payback in battery alone, then a battery with solar pv would have a greater payback.

Secondly, most inverters are connected online now, and do provide the features you are talking about. The one I am getting iantalled will do just that.

KCross

wexfordman2 wrote: »

Sorry kc, but you are.missing the point.


Fristly, you referred to a 15yr payback in a solar with battery, I queried that showing a payback of 15yrs for a battery system that is purely for night rate charging.

So my point was, that if there is a 15yr payback in battery alone, then a battery with solar pv would have a greater payback.

Secondly, most inverters are connected online now, and do provide the features you are talking about. The one I am getting iantalled will do just that.

I understand your point fine and I've explained already the logic to why that example doesnt stack up unless the system is automatically adjusting itself on a daily basis in advance based on weather forecasts.

Does your inverter do that? If yes, as I already said, I'd like to know exactly what inverter that is, so I can research it for myself.

If it doesnt auto adjust based on forecasts you wont get a full charge/discharge cycle every day.

The one _dof_ posted sounds promising but any of the inverters I was quoted for did not have the ability to auto adjust each day like that. I'd be surprised if yours does but please do detail what one you are getting so we can all learn.

KCross

_dof_ wrote: »

I had heard the CEO of Moixa discussing it in an interview and my understanding was that it was all automatic, the smart controller learned your usage patterns and took the weather forecast and your usage patterns into account to automatically adjust the charging and of the battery to maximize usage of the PV and minimize import of the grid at high rate and minimize the export to the grid (assuming no FIT).

So, if it knew that it would be cloudy tomorrow and had learned that your PV installation would only generate a small amount, it would charge the battery from the grid overnight to nearly full, but if it was forecast to be sunny tomorrow and your usage pattern showed that the PV wouldn't cover the first couple of hours of demand, then the battery would be charged just enough overnight to cover that shortfall, based on the prediction that the PV would generate enough to cover the house demand and charge the battery for the rest of the day.

But I could be wrong. If you get more details from them, please do share.

You are correct.
https://youtu.be/aOWetRn1J1A?t=855

One of the founders explains it in the above video... about 2mins of it is all you need to listen to.

Worth listening to the rest of it if you're interested in V2G as well but the 2mins I've given above explains the weather forecasting and machine learning/AI stuff.

It does sound pretty cool and it would significantly change the ROI.

However, the quotes I got from the SEAI registered guys were for Solis or Trannergy inverters and they dont do this AI stuff.

So, if you dont charge the battery using night rate and then there is no excess the following day you end up getting no energy in the evening from the battery and vice versa if you top up the battery at night and then you have excess Solar during the day the battery wont be able to take it because its already full so you've lost out on the free excess, which is the point of getting a battery in the first place. This AI thing solves that but its not the norm and none of my quotes included it.


I sent Moixa an email for more info so I dont know if their system works in Ireland or is it UK weather only for now or do they even supply the system outside UK. I suspect they dont because a key piece of what they do is GridShare where they sell your energy back to the grid (Virtual FiT). So I'd say they are focussed on making that a success in the UK first.

If I hear back I'll post again. Thanks for sharing it anyway, its interesting. This Solar tech stuff is evolving.