Domestic solar PV quotes 2018

unkel wrote: »

Aye that's fair enough. If you never put on your appliances at night even though you do have night rate electricity, then running them on solar PV is worth the full 17c/kWh or so day rate to you

I don't have night rate yet. Luckily I get to charge the car at work but if that changes then I'll have to get it in to charge from home at night.

Aye that's fair enough. If you never put on your appliances at night even though you do have night rate electricity, then running them on solar PV is worth the full 17c/kWh or so day rate to you

unkel wrote: »

Because instead of using the diverter, you can heat your water with an efficient gas or oil boiler (if you have one), which costs about 4c/kWh

In a similar vein, charging your car (or running your dish washer) is worth 8c/kWh because instead of with solar PV, you could charge your car at night at the night rate, which costs 8c/kWh

The one thing that makes me disagree with this a bit is in my case I'd have to put a price on sleeping well. Putting on the appliances in my house at night is very noisy. I wouldn't be able to sleep properly.

niallers1 wrote: »

If bright out the panels could generate most of the 3kw needed but even if they didn't the battery would supply the short fall.

If the battery is charged. And don't discount the base load of the house that runs in the background. That could also easily be a few hundred watt.

I have a similar issue with my car. As a default it charges at 7.2kW. Which even with the sun blasting down, would cost me more to charge partially from the grid, than it would cost me to charge at the night rate. Pointless. There is a setting in the car that I can charge at medium or at low rates. I have to find out what they are but I believe the low rate is just 6A (so about 1.4kW). That would do nicely on sunny days

wexfordman2 wrote: »

Why is diverting to the immersion only 4c/kwh ?

That's the price of Gas so you could just heat with gas as that is what you should be comparing with.

wexfordman2 wrote: »

Why is diverting to the immersion only 4c/kwh ?

Because instead of using the diverter, you can heat your water with an efficient gas or oil boiler (if you have one), which costs about 4c/kWh

In a similar vein, charging your car (or running your dish washer) is worth 8c/kWh because instead of with solar PV, you could charge your car at night at the night rate, which costs 8c/kWh

wexfordman2 wrote: »

Turning the immersion on or off based on your pv producing excess won't be the most effective way if doing it. Say the element in your immersion is 3kw, that means if you are generating 1kw excess, you turn on your immersion, and now you are 2kw down.

My understanding of the way the diverters work, is that they only send to the immersion the excess, so in the scenario above, 1ke excess goes to the element, and you won't be 2kw down .

If bright out the panels could generate most of the 3kw needed but even if they didn't the battery would supply the short fall.

wexfordman2

unkel wrote: »

I will be using pretty much 100% of my PV for the next month or two for my hobby which uses a lot of electricity. Towards the summer I will be phasing this hobby out, so I have a lot of spare capacity.

I work more often than not from home and have an EV. So I'm contemplating a smart EV charger that sends excess production to the car. This would cost me 600 for the charger minus about 200 I'd get for my old charger, so just 400. Diverting to the car is worth 8c/kWh. Diverting to immersion is only worth 4c/kWh, so a poor return (and I already have solar thermal )

Another thing I'm contemplating is an AC side battery, just the smallest unit to take advantage of the 1000 subsidy

Why is diverting to the immersion only 4c/kwh ?

wexfordman2

niallers1 wrote: »

Battery definitely evens out things but in Summer I'll definitely end up giving away a lot of it even with the battery. I don't think I'll buy a diverter. Not sure if it would see the battery as generation and drain it too much. Will just flick on the immersion when I'm home if nothing else is consuming it.

I also put my appliances on delayed start . Washing machine, dryer and dishwasher set to come on at different times helps make the most of the daylight.

My consumption was about 3200kw/year but I have an electric car now and two daughters that will use a lot in the future.

Turning the immersion on or off based on your pv producing excess won't be the most effective way if doing it. Say the element in your immersion is 3kw, that means if you are generating 1kw excess, you turn on your immersion, and now you are 2kw down.

My understanding of the way the diverters work, is that they only send to the immersion the excess, so in the scenario above, 1ke excess goes to the element, and you won't be 2kw down .

I will be using pretty much 100% of my PV for the next month or two for my hobby which uses a lot of electricity. Towards the summer I will be phasing this hobby out, so I have a lot of spare capacity.

I work more often than not from home and have an EV. So I'm contemplating a smart EV charger that sends excess production to the car. This would cost me 600 for the charger minus about 200 I'd get for my old charger, so just 400. Diverting to the car is worth 8c/kWh. Diverting to immersion is only worth 4c/kWh, so a poor return (and I already have solar thermal

)

Another thing I'm contemplating is an AC side battery, just the smallest unit to take advantage of the 1000 subsidy

unkel wrote: »

How the hell did you manage to do that, do you have a very high background load or do you reckon the battery evens it all out?

I wouldn't worry about the few hundred kWh you are likely to give away for free. Do not divert, it will only cost you money. If you don't mind me asking, what was your annual consumption in kWh before your system?

I've a 4kwp system up and running since last weekend, next phase for me is maybe a battery...

Battery definitely evens out things but in Summer I'll definitely end up giving away a lot of it even with the battery. I don't think I'll buy a diverter. Not sure if it would see the battery as generation and drain it too much. Will just flick on the immersion when I'm home if nothing else is consuming it.

I also put my appliances on delayed start . Washing machine, dryer and dishwasher set to come on at different times helps make the most of the daylight.

My consumption was about 3200kw/year but I have an electric car now and two daughters that will use a lot in the future.

zdragon wrote: »

spending couple of thousands just to give away free energy, doesn't make sense at all

giving away free energy could be cheaper than using a battery

KCross wrote: »

Your comment that "4kW panels will generate more than I need" gives the impression that you think it will reduce your bills by that same amount.... you realise the majority of it will go unused because you wont be at home utilising 4kW all day long and during the winter it will be generating close to "nothing".

Maybe you do understand that but just want to make sure you do as that comment makes it look like you don't!

I don't consider a system without battery. spending couple of thousands just to give away free energy, doesn't make sense at all

niallers1 wrote: »

I have a 4.2kw PV system with 5kwh battery. Since mid september I've only given away 22kwh to the grid for free.

How the hell did you manage to do that, do you have a very high background load or do you reckon the battery evens it all out?

I wouldn't worry about the few hundred kWh you are likely to give away for free. Do not divert, it will only cost you money. If you don't mind me asking, what was your annual consumption in kWh before your system?

I've a 4kwp system up and running since last weekend, next phase for me is maybe a battery...

I have a 4.2kw PV system with 5kwh battery. Since mid september I've only given away 22kwh to the grid for free.
Summer will be difficult to store/use all. Will probably need to heat water with excess.

Even with above setup i'd expect to have to buy about 1000kw/year from the grid.

I'd love to see net metering or a decent feed in tariff .

KCross

zdragon wrote: »

my power consumption is 3200 kW/ year
so 4kW panels can generate more than I need.

Your comment that "4kW panels will generate more than I need" gives the impression that you think it will reduce your bills by that same amount.... you realise the majority of it will go unused because you wont be at home utilising 4kW all day long and during the winter it will be generating close to "nothing".

Maybe you do understand that but just want to make sure you do as that comment makes it look like you dont!

denismc

zdragon wrote: »

would you share the datat?
daily generated and daily consumed?

Some of my figures from last year, the system was installed in April.
My wife is at home fulltime with 2 toddlers and I work shift so we probably get to use more during the day than the average family.

My consumption from the grid hasn't decreased that much as the installation of the panels coincided with the arrival of twins! which increased my consumption quite a bit.

my power consumption is 3200 kW/ year
so 4kW panels can generate more than I need.

pity all installers are offering 2kW systems without storage , would be the optimal solution for many consumers.

Fotoman 3.995kW Compare: Tips
Year▼
Generated

Efficiency

North Hampshire
4KW system

Exported
FIT Credit Low High Average
Comments
2019 117.472kWh 0.840kWh/kW 117.472kWh 0.146kWh 11.960kWh 3.356kWh Partial Year (35 days)
2018 3.853MWh 2.643kWh/kW 3.853MWh 0.061kWh 29.110kWh 10.556kWh
2017 3.521MWh 2.415kWh/kW 3.521MWh 0.311kWh 27.880kWh 9.647kWh
2016 3.775MWh 2.582kWh/kW 3.775MWh 0.218kWh 27.380kWh 10.314kWh
2015 3.791MWh 2.600kWh/kW 3.791MWh 0.103kWh 29.420kWh 10.386kWh
2014 3.758MWh 2.577kWh/kW 3.758MWh 0.183kWh 28.200kWh 10.295kWh
2013 3.825MWh 2.841kWh/kW 3.825MWh 0.047kWh 29.721kWh 10.480kWh
2012 3.509MWh 2.400kWh/kW 3.509MWh 0.053kWh 28.150kWh 9.587kWh
2011 406.643kWh 1.049kWh/kW 406.643kWh 0.276kWh 17.880kWh 4.192kWh Partial Year (97 days)

pvoutput org has a lot of interesting real data ,
data below was generated near Liverpool

Lyndale power station 4.000kW Compare: Tips
Date▼ Generated Efficiency Exported Peak Power Peak Time Conditions Temperature
Comments

21/12/11 1.400kWh 0.350kWh/kW 1.400kWh 0.850kW - Mostly Cloudy 0 to 5C
20/12/11 1.200kWh 0.300kWh/kW 1.200kWh 0.850kW - Mostly Cloudy 0 to 6C
19/12/11 0.950kWh 0.238kWh/kW 0.950kWh 0.700kW - Showers 0 to 5C
18/12/11 1.400kWh 0.350kWh/kW 1.400kWh 0.800kW - Fine 0 to 7C
17/12/11 1.400kWh 0.350kWh/kW 1.400kWh 1.200kW - Fine 0 to 8C
16/12/11 1.400kWh 0.350kWh/kW 1.400kWh 0.800kW - Cloudy 0 to 8C
15/12/11 1.400kWh 0.350kWh/kW 1.400kWh 0.900kW - Mostly Cloudy 0 to 6C
14/12/11 1.400kWh 0.350kWh/kW 1.400kWh 0.900kW - Mostly Cloudy 0 to 5C

What data? Rule of thumb for a 5kwp panel south facing in a decent part of Ireland is that it will generate roughly 5MWh with a daily peak around midday and a yearly peak in the summer

You will have to measure your own consumption data. And make some adjustments for when you can move night time use to daytime use (i.e. put the dishwasher in the middle of the day provided it's not raining / very overcast, etc.)

unkel wrote: »

I hasten to add that I have a large solar thermal setup, my only family car is a full EV and I have just increased my PV setup to a total of almost 4kwp

But we have to be realistic about the figures and not kid ourselves with overly optimistic projections...

would you share the datat?
daily generated and daily consumed?

I hasten to add that I have a large solar thermal setup, my only family car is a full EV and I have just increased my PV setup to a total of almost 4kwp

But we have to be realistic about the figures and not kid ourselves with overly optimistic projections...

You're using 3MWh per year. Your PV will generate 5MWh per year. Problem is that you use a lot of your electricity when your PV is not generating. Meaning most of your generated electricity will be lost and only a part (maybe half if you put a huge effort in) of your current consumption will be covered by PV. And you still have the same fixed electricity costs. So your savings are very optimistically 1500 units * 17c = €250 per year

A (subsidised) battery will alleviate this, but these have even longer pay back times than subsidised PV...

unkel wrote: »

You wish. That's if all the electricity you use now will be covered by solar. You'd do very well to replace half of what you are using now...

this calculation is an assumption that I get 60% from solar. but I think 5kw system will give me an average of 30% (here is where I need real data for Ireland)

zdragon wrote: »

Breaking point is around 8.5 years

You wish. That's if all the electricity you use now will be covered by solar. You'd do very well to replace half of what you are using now...

Reading this forum carefully . I still have doubts that solar is worth it.

Here is my situation in numbers:

my annual electricity bill is ~€922 (8.3 kW/day).
Solar system 5kW (quote taken from this thread - €5200 after grants)

My calculations are based on following assumptions

electricity consumption stays flat :8.3 kW/day
electricity price inflation a 3%/year

Breaking point is around 8.5 years

for a 6% inflation the breaking point is 7.5 years

but my calculations are missing the real energy generated by a 5kW system so it could be longer before costs are recovered.