Makes more sense to export unused solar than use to heat water/charge car

B

Buddyboy

Registered User
Messages
819
I've just had solar installed and very happy with with it so far. I'm on a day/night rate with Electric Ireland with cost of 13c night and 26c day.

Smart meter installed.

They buy back any energy with microgeneration at 19.5c per Kw.

So, if I'm correct, it is cheaper for me to charge the electric car at night, at 13c per kW, because if I charge it during the day, from solar, I lose 19.5c per kW that I could have sold back to the grid.

Also, as I've a heat pump that has a COP of around 3.0 to heat water, it is costing me 4c to heat the equivalent for water during the night, so I would lose even more by using the solar to heat water during the day. Solar is using an Eddie/electric element with a 1:1 kW/heat ratio.

Am I correct, because I've the feeling that I'm missing something obvious and fundamental (too good to be true and all that)?
 
Last edited:
Too good to be true...

My understanding is that Euro400 is allowed to be earned under Clean Energy Generation before taxes etc... kick-in.
Euro400 / (365 * 0.75) = a paltry Euro1.46 per day
If there's a couple on the bill then Euro800 I believe.

(I applied the 0.75 to allow for darker months)

If you are testing those limits then there's a stronger economic argument for storing energy in heated water and/or battery.
 
RoboMac said:
My understanding is that Euro400 is allowed to be earned under Clean Energy Generation before taxes etc... kick-in.
Euro400 / (365 * 0.75) = a paltry Euro1.46 per day
Click to expand...
Except it's extremely easy to choose for your solar to power your house first and only after that does any surplus go to the grid. The feed in tariff is invariably lower than the day rate so doing that is a no-brainer.

In my case I've generated over €1,100 worth of electricity in 11 months, based on the FIT . But I've used a lot of that power myself, so the actual effect has been to cut my consumption from the grid by about 50% and the FIT pays for the remainder of my usage. I don't get paid for the power I use directly and therefore I haven't crossed the threshold of €800 limit at which Revenue might start to care.

RoboMac said:
Too good to be true...
Click to expand...
It really isn't.

7KW East-West array, 4.75MWh generated to date. About 2.8MWh exported @ 24c per kwh for €670 total. The FIT is now reduced to 20c, so I'm not going to receive over €800 for the full year at this stage.

I'm also not going to be paying for electricity any time soon, hurray.
 
By "too good to be true" I meant there's a potential revenue bill. That's the only gotcha from what I can tell.

I've a similar setup 5kW produced 4.4mWh with 2.3mWh exported to grid.

BIG-notorious said:

Except it's extremely easy to choose for your solar to power your house first and only after that does any surplus go to the grid.
Click to expand...
What have you done help achieve this? Batteries, Electric Car, EDDI / Smart Immersion, or something else?
 
BIG-notorious said:
In my case I've generated over €1,100 worth of electricity in 11 months, based on the FIT . But I've used a lot of that power myself, so the actual effect has been to cut my consumption from the grid by about 50% and the FIT pays for the remainder of my usage. I don't get paid for the power I use directly and therefore I haven't crossed the threshold of €800 limit at which Revenue might start to care.
Click to expand...

Thanks for all the replies, and just so I'm clear....
If I generate, all in, 1,000€ in a year. 500€ of that is used at the time of generation, and €500 is input into the grid. If I use that €500 (input into the grid) during the course of the year, for example in the winter months when I'm not generating anything, then the net is that I don't have to pay for any electricity, and my net "payment" for revenue purposes is 0.

If this is the case, then I'm in effect using the grid as a long term battery.
 
RoboMac said:
What have you done help achieve this? Batteries, Electric Car, EDDI / Smart Immersion, or something else?
Click to expand...
On the SolisCloud app, I tapped on "Modify Info" and then under Info/More info I changed "Grid Connection Type" from "Maximum Export" to "Surplus Export".

No further action on my part was required. I looked at batteries, eddi, and an electric car (none of which meet my definition of "extremely easy" BTW) and none of them made economic sense, they would have just been superfluous bling. The installation I did get is equivalent to about 25% pre-tax return on the investment for a few decades which was good enough that I nearly took the installer's arm off for it in case they changed their mind!
Buddyboy said:
If I generate, all in, 1,000€ in a year. 500€ of that is used at the time of generation, and €500 is input into the grid. If I use that €500 (input into the grid) during the course of the year, for example in the winter months when I'm not generating anything, then the net is that I don't have to pay for any electricity, and my net "payment" for revenue purposes is 0.
Click to expand...
My understanding is that the income for Revenue purposes is €500 for what you exported. Which is why it's worthwhile getting a second (or even third if your setup is big enough) name on the electricity bill.
 
Buddyboy said:
looks like Mrs. buddyboy will be going on the bill :)
Click to expand...

As will Mrs Marsupial! (The younger Marsupials would too, only that I can't see my annual income from microgeneration exceeding €800 unless the feed-in tariff increases massively.)
 
Last edited:
BIG-notorious said:
On the SolisCloud app, I tapped on "Modify Info" and then under Info/More info I changed "Grid Connection Type" from "Maximum Export" to "Surplus Export".
Click to expand...
Perfect

Re: 2nd name on bill. It may not be as easy as you'd expect.
My supplier (I won't embarrass them) said this would be a change to contract and incur €200 contract termination fee (I'm fixed) and a new contract could be drawn up with 2 names. However I'd lose my nice fixed rate so I've decided to let contract run with 1 name and then I'll switch ensuring 2 names on contract with new supplier.
 
BIG-notorious said:
I looked at batteries, eddi, and an electric car (none of which meet my definition of "extremely easy" BTW) and none of them made economic sense, they would have just been superfluous bling.
Click to expand...
Can’t understand how you came to this conclusion about a battery. I can import at 14c to offset my daytime usage at 28c, and allow my solar to export at 20c. About to put in a bigger battery so I can justify 7c/32c on an EV tariff - bigger battery means I’ll largely avoid importing at daytime rate, even in winter.
 
@Buddyboy

Hello,

What size system have you installed, if you don't mind me asking, please?

Depending on the size of your system, household electricity use, direction the panels are facing your location etc., you may nene need to worry about Revenue...
 
conor_mc said:
Can’t understand how you came to this conclusion about a battery. I can import at 14c to offset my daytime usage at 28c, and allow my solar to export at 20c. About to put in a bigger battery so I can justify 7c/32c on an EV tariff - bigger battery means I’ll largely avoid importing at daytime rate, even in winter.
Click to expand...
How much does a battery cost, how long does it perform at it's max, and how long until it realistically needs replacing..?
 
You must log in or register to reply here.
Back
Top