Following another round of inverter issues, and generation meter misbehaviour I decided to actively investigate on–site battery storage.
Settling on a DC–coupled* Tesla Powerwall (their curvy first version) with a SolarEdge inverter.
(† There are 21 185W (Watt) Sharp panels, originally fitted August 2011. The original system is at least 80% paid off, not counting bill reduction(s).)
The result being: more use of electricity generated by photonic interactions with silicon wafers. (Some science.)
The upshot of this: many days’ nighttime usage covered by battery capacity (≤6.4kWh), negligible grid import, and bills where standing charge dwarfs unit expenditure.
e.g. “… for the period 29 June 2017 to 28 September 2017
- 12 units (1kWh kilowatt hour)
- 15.11p ex 5% VAT = 1.81 ex 5% VAT (value–added tax.)
- 92 days’ standing charge
- 30.87p ex 5% VAT = 28.40 ex 5% VAT
With the higher–level FIT (feed–in tariff), the 3.8+MWh generated over the year (translated to money in the bank) has been enough to pay those bills, and more…