A Behind the Scenes Take on Lithium-Ion Battery Prices
It&#x27;ll be great when these battery cost reductions filter through to home batteries. At the moment a Tesla Powerwall 2.0 costs $6,700 for 13.5 kWh, so $496&#x2F;kWh, which is doesn&#x27;t work as a financial investment.<p>We&#x27;ve got a solar installation and so I have been considering getting a battery for either off peak to peak cost arbitration, or capturing excess solar energy for use at night.<p>In the UK a Powerwall costs around £9,000 to £11,000 including additional hardware, taxes and installation. Based on some estimates (see below), at current prices I think you would be lucky to get a third of that back through energy bill savings.<p>If the Powerwall sold at closer to its battery pack cost, it might be worth considering.<p>Off peak to peak arbitration<p><pre><code>  Peak cost of energy (£ per KWh) - £0.1573 
  Off peak cost of energy (£ per KWh) - £0.0815 
  Saving per KWh - £0.0758 
  Powerall 2 - maximum lifetime throughput - non solar uses (KWh) -  37800 [1]
  Lifetime power bill saving £2,865.62
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Solar PV energy capture<p><pre><code>  PV System Size (KWp) - 5.76 
  Solar irradiation - 986 
  Annual yield (KWh) - 5679 
  Annual energy exported to grid - assume 70% - 3976 
  Annual proportion that could be captured - estimate 50% - 1988 [2]
  Peak cost of energy (£ per KWh) - £0.1573 
  Annual saving - £312.66 [3]
  Warrant Period (years) - 10 
  Total saving over warranty period - £3,126.57
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[1] <a href="https:&#x2F;&#x2F;www.tesla.com&#x2F;sites&#x2F;default&#x2F;files&#x2F;pdfs&#x2F;powerwall&#x2F;powerwall_2_ac_warranty_europe_1-5_english.pdf" rel="nofollow">https:&#x2F;&#x2F;www.tesla.com&#x2F;sites&#x2F;default&#x2F;files&#x2F;pdfs&#x2F;powerwall&#x2F;pow...</a><p>[2] In winter months, all solar energy could be captured, but in summer the panels will produce more than the Powerwall is able to store.<p>[3] Doesn&#x27;t factory in degradation over the period, which Tesla quotes at 80% capacity after 10 years