Pv panels, am i getting my maths wrong

hairyslug

Firstly, I know very little about all this so please correct if I'm wrong with any if this.

Had a quick look at my last year's bills, we average about 30kw a day.

I've also been looking at Electric Ireland's offer. It includes 6 x285watt panels and diverted for 5k.

Electric Ireland's site estimated that the panels would harvest 1610kwh per year (I'm North Wexford, the estimate is for Cork) and a financial saving of 253e. This would result in an average of 4kwh being saved per day. I'll be honest. I'm more in this for (after an initial payment) seeing a dramatic cut in my electricity coming from the grid but with these figures, I'm just not seeing it.

Are the estimates of the electric Ireland site similar to what others are seeing.

rolion

Hi,

Welcome...

Firstly,no offence,but how did you manage to get around 30KWh per day !??
You will need a massive PV farm to cover that type of consumption ...
My advice is to look at the current setup,see what can you reduce or avoid or reschedule as time VS consumption VS living comfort.

It took me one year, start to finish to implement a PV system,by monitoring the Sun in the sky related to home / roof position,coverage and so on. Once you have the basics sorted,getting panels and install is the easy part.
Even with the panels installed NOBODY can confirm the savings based on some past times "estimates" !
As per my other topic, the PV generation across an hour you could have up and downs from 5KWh to a mere few hundreds.

All parameters been equal,a PV will save you money in the long run but not at the predicted rates by today's marketing dept.

Enjoy it...

hairyslug

rolion wrote: »

Hi,

Welcome...

Firstly,no offence,but how did you manage to get around 30KWh per day !??
You will need a massive PV farm to cover that type of consumption ...
My advice is to look at the current setup,see what can you reduce or avoid or reschedule as time VS consumption VS living comfort.

It took me one year, start to finish to implement a PV system,by monitoring the Sun in the sky related to home / roof position,coverage and so on. Once you have the basics sorted,getting panels and install is the easy part.
Even with the panels installed NOBODY can confirm the savings based on some past times "estimates" !
As per my other topic, the PV generation across an hour you could have up and downs from 5KWh to a mere few hundreds.

All parameters been equal,a PV will save you money in the long run but not at the predicted rates by today's marketing dept.

Enjoy it...

No offence taken, I'm coming at this completely blind.

I'm using 25/30 units per day that's where the kWh mix up is. (Am I correct in thinking 1 unit = 1kw)

My main question would be, are electric Ireland's estimations correct in that the panels will only create 1600kw per year.

The house is N/E facing, when you mention reschedule, do you mean when washing machine/dishwasher etc get run?

KCross

1 unit = 1kWh

rolion

Is hard to say yes or even ,no !
I dont know the system performance.I am not aware of your house location,roof position in relation to Sun and roof angles summer vs winter.
It depends on a lots of factors,weather,cabling and shading...
The PVs could be up & down across few minutes so few clouds ,rain could impact "the harvesting".

Not lastly,even if the system makes the 1,600 ...BIG Q is how do you get them to work for you and not for the grid !?? During day time,when the system is at the peak of production,how do you "harvest" them to power your appliances or cover your daily minimum average consumption ?
Take readings of your meter,every day in the morning,at lunch and evening.Then,at bed time.After that you can see when you have the peak consumption,average power consumption,as the electricity required from your panels will cover only day time (summer more,winter more less).

My setup is working fine but i kind of lost interest in generation numbers and figures...i know is doing the job,checking once few days for anomalies and /or errors. Inverter is installed at the main door,so every time i'm in or out,i can see and hear for any issues and see performance figures.
I have given to the grid,only in May,June and July over your quoted 1,600KWh figures.

Any decison you make is better than inaction or give up on the system.Figures will not make financial sense today,even with bigger PVs systems.

Enjoy it..

unkel

hairyslug wrote: »

we average about 30kw a day.

That's about 10k kWh per year. That's a lot, about 3 times the national average. Big house, heat pump, electric heater(s), electric shower(s), electric car(s)? Do you have a night meter and are you on the cheapest rates? Are there any savings to be made in your daily use? I.e. install a pumped shower instead of using electric showers?

Answer these questions and you might save yourself a lot more than by installing PV

hairyslug wrote: »

I've also been looking at Electric Ireland's offer. It includes 6 x285watt panels and diverted for 5k.

Electric Ireland's site estimated that the panels would harvest 1610kwh per year (I'm North Wexford, the estimate is for Cork) and a financial saving of 253e.

The Electric Ireland installation is very expensive. I wouldn't go with them. But their figure of harvest is about right, provided your PV panel setup is ideal (simplistically said - south facing). Most of Leinster is pretty ok.

The 1610kWh harvest is NOT worth EUR253 though. Only a fraction of it. First of all it implies all of your harvest will be used. It will not. You will lose quite a bit of it into the grid and you will get nothing for that. Then it implies a rate of 16c per kWh. The day rate in Energia is 13c and the night rate is less than 7c (you can charge a car or run the washing machine at night)

So total saving is more like €100 (very rough guess) per year unfortunately...