Phwarrrrr!
Had a guy come and visit us this morning to talk about the viability of us purchasing a Tesla Powerwall rechargeable battery .
On doing a simple historic using a compound interest type calculation, using the high & low electric meter readings and the FIT income. It looks like we've earn't almost £ 1080 more than we paid for the solar PV system five years ago.
We paid by bank transfer the afternoon it was fitted & working …… no loans or credit etc. why pay 86 % or so more if you don't need to ?
The guy couldn't work out why we had an actual 18.3% increase of solar PV FIT when compared by the average . Neither could I at the time But I have sussed it after a few minutes of thinking.
One of the first things he did was to check the orientation of our bungalow , declaring, "Oh your panels should be on the east side of the roof .
He'd used a snazzy digital compass on his laptop that could align to the N th degree .
I said to him check to see if you are using true north or magnetic north it will make several degrees difference to the reality of the sun .
He'd not realised there was a difference called magnetic variation , nor did he work out that as the days are longer in summer means the amount of sun light must be available for more hours . This also caused him to miscalculate where the sun rises and sets . I said it rose in slightly east of north east & set slightly north of north west from about the end of May to the end of July & couild give 15 plus hous of useable enegy eah day in that period .
He redid his calculations and still found we were way ahead of the estimated generation .
I then showed him next doors bungalow roof, which is five feet above our bungalow & their long light coloured bungalow side wall . Told him that they became sun energy reflectors & that their two large side windows that face our bungalow were as good as mirrors from 09.00 till about 14 .00hrs reflecting even more energy on to our panels when the heat of the day sun took over till it was almost sunset ..
Armed with his recalculations it looks like a power wall installation costing £7.5 K should pay for itself in eight or so years then be in profit for about the next 12 to 20 years.
Sounds a lot better ROI than you can normally get from a bank / building society and nearly as good as the ROI from a proper investment vehicle till you get to the 35 /40 year compound interest point .
Our next new car will like as not be an all electric one with a 300 mile range, such is the tremendous range being aimed for . It is an ideal candidate to be charged up if you have a power wall .
Currently it costs us about 70 p to whack a 31 mile charge into the PHEV using off peak electricity or for free in the daytime if it is a really good sunny day.
Whereas a gallon of petrol is approx = 5 x £1.38 round here so about £6.69 a gallon & gives up about 35 mile
Good value, especially when you consider that the government of the day will take any money off you that they can when you're in your older years . .
Topic: Power walls /battery banks (Read 6761 times)
