Rocketing electricity prices and EV Viability
Discussion
DonkeyApple said:
skinnyman said:
My man maths makes a solar panel/battery system stack up:
5kW system with an 8kW battery = £10k
Provides around 4000kW/yr
4000kW @ 40p = £1600
6.25yrs payback
Even if electricity somehow returns back to 20p that's a 12yr ROI.
With energy prices being what they are I don't see how a solar panel/battery system doesn't stack up
For me it's that payback time that pretty much ensures it doesn't stack up. Capex is far too high for such small returns which is what results in needing a huge time duration just to break even. You then are entering the realms of maintenance spend which will potentially decimate those fragile numbers. 5kW system with an 8kW battery = £10k
Provides around 4000kW/yr
4000kW @ 40p = £1600
6.25yrs payback
Even if electricity somehow returns back to 20p that's a 12yr ROI.
With energy prices being what they are I don't see how a solar panel/battery system doesn't stack up
But we'll see lots of people investing in long term solar on the back of short term gas costs.
In simple terms, paying £10k just to possibly get that £10k back in ten years time so long as there are no problems isn't a logical financial decision. Especially given the likely scenarios in ten years time of much cheaper energy storage, lower dependency on gas.
As a consequence even in the darkest winter days, the battery will get me through another charge cycle, without having to dip into peak rate. Add to that the near self sufficiency between March and early November and FIT payments, for those early enough to claim them, my man maths thinks 10 years is somewhat pessimistic.
FeelingLucky said:
The big gains (battery capacity allowing) are from never using peak rate ever again. A well managed battery will charge up on 5p Kw/h overnight only as much as it needs to, taking into account a solar estimate for the following day from the manufacturer. It doesn't always get it right, but it's biased toward being conservative, so tends to slightly over charge rather than under.
As a consequence even in the darkest winter days, the battery will get me through another charge cycle, without having to dip into peak rate. Add to that the near self sufficiency between March and early November and FIT payments, for those early enough to claim them, my man maths thinks 10 years is somewhat pessimistic.
Interesting - do any battery systems do the “solar estimate” out of the box?As a consequence even in the darkest winter days, the battery will get me through another charge cycle, without having to dip into peak rate. Add to that the near self sufficiency between March and early November and FIT payments, for those early enough to claim them, my man maths thinks 10 years is somewhat pessimistic.
Was having a read up on GivEnergy and a chap had used Solcast to get the estimates, combined with some scripting by him to work out how long to charge for at the cheap rate each night.
Powerwall seems to learn from your historic PV generation and usage, but couldn’t see that it looked at the weather forecasts.
danp said:
FeelingLucky said:
The big gains (battery capacity allowing) are from never using peak rate ever again. A well managed battery will charge up on 5p Kw/h overnight only as much as it needs to, taking into account a solar estimate for the following day from the manufacturer. It doesn't always get it right, but it's biased toward being conservative, so tends to slightly over charge rather than under.
As a consequence even in the darkest winter days, the battery will get me through another charge cycle, without having to dip into peak rate. Add to that the near self sufficiency between March and early November and FIT payments, for those early enough to claim them, my man maths thinks 10 years is somewhat pessimistic.
Interesting - do any battery systems do the “solar estimate” out of the box?As a consequence even in the darkest winter days, the battery will get me through another charge cycle, without having to dip into peak rate. Add to that the near self sufficiency between March and early November and FIT payments, for those early enough to claim them, my man maths thinks 10 years is somewhat pessimistic.
Was having a read up on GivEnergy and a chap had used Solcast to get the estimates, combined with some scripting by him to work out how long to charge for at the cheap rate each night.
Powerwall seems to learn from your historic PV generation and usage, but couldn’t see that it looked at the weather forecasts.
However, when I arise and grab my mobile from charging, I invariably look on the Tesla app, specifically the Powerwall charge state, and how much off-peak it used to get there. On the days where it's charged up to the 90s% the day ahead has ALWAYS turned out to be somewhat grim, and conversely, when it's at 50s or lower % and hasn't charged overnight at all, it's a bright sunny day that follows, it shows these behaviours regardless of charge state or weather previous day.
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