Energy costs

anon_ymous

Assuming that I've calculated everything correctly, assuming I'm producing 4000 kWh a year, and assuming this calculator is correct. Costs are based on projected April 2023 prices 

https://www.in2gr8tedsolutions.co.uk/index.php

Then my costs are as follows :

I require typically around 300 kWh a month or 3700 kWh a year.

That assumes I'd generate 808 kWh between October and February. I'd also need to pull a further 733 kWh

In April 2023 prices that's £396 + standing charges for that period 

For the other months, I'd basically have exported 3192 kWh of energy where my own energy requirements are 2156 kWh ie: 1036 kWh to export 

I'd assume it's at least 22.5p / kWh given Octopus currently give me at least 15p ie: a "profit" during that period of £233.10

Essentially I'd import 733 kWh but export 1036 kWh over the course of the year 

£396-233.10 = £162.90 + standing charges, or probably closer to £15/month on leccy

___________

The other alternative is charge at night time for 18p (Assuming that's the rate as right now it's 12p)

And likely sell back at 6.2p. Current rate is 4.1p

That makes for easier maffs

Import 3700 kWh at £666, and store in your batteries 

Export 100% of your solar at 4000 kWh, or £248

£666-248 = £418 + standing charges, or around £35/month. It's probably worth it if you've got an EV 

Petriix

It's slightly more complicated than that because you can't just average out usage over a period of months and assume your battery will manage all the peaks and troughs in generation (unless it's ridiculously big). I would assume that you'll export and import more than that. I also wouldn't assume anything about April prices.

anon_ymous

Petriix said:

It's slightly more complicated than that because you can't just average out usage over a period of months and assume your battery will manage all the peaks and troughs in generation (unless it's ridiculously big). I would assume that you'll export and import more than that. I also wouldn't assume anything about April prices.

The battery size I'm getting is 15 kWh which should be enough to go through the peaks and troughs 

propnut

waqasahmed said

The battery size I'm getting is 15 kWh which should be enough to go through the peaks and troughs 

Is that actual useable capacity or headline capacity? They will always sell you on the big number and not tell you that it is not generally true. My setup was meant to be 7.2kwh = 3 x Uhome LFP 2400's but actual useable capacity is only 2200watts per battery = 6.6KW's 

I learned yesterday that the Greenlinx batts can discharge to 100% but even that I don't believe. I think they will have fudged some buffer space in there to make it appear to be 100% . Batteries irrespective of chemistry don't like being flattened.

Screwdriva

Your consumption doesn't appear to justify batteries, as you've highlighted.

Reed_Richards

waqasahmed said:

The other alternative is charge at night time for 18p (Assuming that's the rate as right now it's 12p)

And likely sell back at 6.2p. Current rate is 4.1p

That makes for easier maffs

waqasahmed said:

The battery size I'm getting is 15 kWh which should be enough to go through the peaks and troughs 

Not only does it make for easier "maffs", it also makes it easier to determine the correct size of your battery.  If you use 3700 kWh per year that's about 10 kWh per day.  If some of this is already night-time usage then you only need a battery that is big enough to cover 1 day's worth of daytime usage so maybe 10 kWh would be sufficient capacity.  Batteries are expensive and are said to have a shorter life than solar panels so you don't want to pay for more battery capacity then you will use.

Oscarmax

waqasahmed said:

Assuming that I've calculated everything correctly, assuming I'm producing 4000 kWh a year, and assuming this calculator is correct. Costs are based on projected April 2023 prices 

https://www.in2gr8tedsolutions.co.uk/index.php

Then my costs are as follows :

I require typically around 300 kWh a month or 3700 kWh a year.

That assumes I'd generate 808 kWh between October and February. I'd also need to pull a further 733 kWh

In April 2023 prices that's £396 + standing charges for that period 

For the other months, I'd basically have exported 3192 kWh of energy where my own energy requirements are 2156 kWh ie: 1036 kWh to export 

I'd assume it's at least 22.5p / kWh given Octopus currently give me at least 15p ie: a "profit" during that period of £233.10

Essentially I'd import 733 kWh but export 1036 kWh over the course of the year 

£396-233.10 = £162.90 + standing charges, or probably closer to £15/month on leccy

___________

The other alternative is charge at night time for 18p (Assuming that's the rate as right now it's 12p)

And likely sell back at 6.2p. Current rate is 4.1p

That makes for easier maffs

Import 3700 kWh at £666, and store in your batteries 

Export 100% of your solar at 4000 kWh, or £248

£666-248 = £418 + standing charges, or around £35/month. It's probably worth it if you've got an EV 

Hi like you I am new to all this, over the past 11 months I have kept a detailed Excel spreadsheet. In March we installed 4.4 kWh panel to date we have generated nearly 4400kWh, I am assuming we will generate at least 4500kWh for our first year.

Previously we imported 3900kWh every year, we have a PHEV which accounts for 1300kWh, leaving 2600kWh, we noticed our import dropped dramatically, however in March onwards we were exporting over two third back to the grid. Our energy use was approximately 50% off peak 50% normal rate during March until September.

In Mid October we fitted a 5.8kWh battery we were advised by the company to a battery just to fit our average daily needs, going too would be a waste of money, according to my spreadsheets they were 100% correct. Since fitting the battery in October we have noticed out normal rate consumption has more than halved, we are using more of our generation and slightly more off peak. 

Octopus Go outgoing is currently 4.1,ECO7 outgoing is 15 pence kWh, in March my fixed tariff Octopus Go ends, for me it is going to be more cost effective to use Octopus ECO7

Solarchaser

Oscarmax, eco 7 off peak seems to be 20p/kwh, but intelligent octopus is 10p/kwh off peak.
So if your phev or your charger are compatible,  it may be worth looking at that instead  

Oscarmax

Solarchaser said:

Oscarmax, eco 7 off peak seems to be 20p/kwh, but intelligent octopus is 10p/kwh off peak.
So if your phev or your charger are compatible,  it may be worth looking at that instead  

Octopus has sent through some renewal figures ECO7 17.73 off peak, 45.15 day rate and 47.5 standing charge outgoing 15 pence, unfortunately Octopus Go and Intelligent outgoing only 4.1 pence.

anon_ymous

propnut said:

waqasahmed said

The battery size I'm getting is 15 kWh which should be enough to go through the peaks and troughs 

Is that actual useable capacity or headline capacity? They will always sell you on the big number and not tell you that it is not generally true. My setup was meant to be 7.2kwh = 3 x Uhome LFP 2400's but actual useable capacity is only 2200watts per battery = 6.6KW's 

I learned yesterday that the Greenlinx batts can discharge to 100% but even that I don't believe. I think they will have fudged some buffer space in there to make it appear to be 100% . Batteries irrespective of chemistry don't like being flattened.

Usable.. I've currently got a 3.3 kWh battery, and I can use 3kWh of it. 

ecraig

The real world usage of fully battery only is harder to achieve though.
Let's say you want to put the electric oven on, and the washing machine, and you fancy a cup of tea at the same time - that's going to be too much draw from the batteries at once and you're going to import from grid even though you've got allll this battery power stored up.