Understanding Solar Energy

Original Article ↗ Hacker News Discussion ↗

Speed of Solar Growth & Failed Forecasts

  • Commenters note how quickly PV has scaled, contrasting it with earlier claims that major energy shifts must be slow.
  • Institutions (IEA/IPCC) and prominent analysts are criticized for systematically underestimating solar and wind while overestimating nuclear and CCS.
  • Explanations offered: “hard vs soft energy” cultural bias, underestimation of China’s industrial capacity, and general human difficulty with S-curves and learning curves.

Manufacturing, Costs, and Technology Learning

  • Solar’s price crash is attributed to massive scale-up, “learning by doing”, and piggybacking on semiconductor manufacturing.
  • Specific PV advances mentioned: more efficient polysilicon processes, continuous Czochralski growth, better wafering (diamond wire), dopant shifts (boron→gallium→phosphorus), PERC→TOPCon→HJT/back-contact architectures, and big silver reductions.
  • China’s early, strategic investment in PV manufacturing is credited with much of the price decline; US/EU tariffs are seen as raising costs and slowing deployment.

Storage: Batteries vs Everything Else

  • One camp argues the practical contenders this decade are:
    • Batteries for diurnal storage,
    • Pumped hydro for long-duration,
    • “Final-form” storage (heat as heat, etc.), plus overbuilding renewables.
  • Others push back, emphasizing:
    • Political and regulatory barriers over technical ones,
    • Complementary roles for thermal, compressed air, power-to-X, and phase-change/TCES systems,
    • Hydrogen or synthetic fuels and seasonal storage, with disputes over round-trip efficiency vs capital cost.
  • Evidence cited that pumped hydro is mostly used intra-day and is geographically limited; some analyses show hydrogen outperforming PHES for multi-month storage, others dispute the cost assumptions.

Household Use, Hot Water & Heat Pumps

  • Many see domestic hot water and HVAC as low-hanging fruit:
    • Use PV directly to heat water (resistance or heat pumps),
    • Treat water tanks and building thermal mass as cheap “batteries”.
  • Debate over PV vs solar thermal: older intuition favors thermal, but current module prices often make PV+resistance cheaper and more flexible.
  • Heat pumps are defended as efficient even in cold climates, but economics depend heavily on local gas/electric prices and insulation levels.

Grid, Policy & Interconnection

  • US installation costs (solar, batteries, heat pumps) are seen as inflated by permitting, customer acquisition, tariffs, and fragmented regulation; comparisons made to cheaper Australian and European installs.
  • Interregional transmission and intercontinental grids are highlighted as major tools for smoothing intermittency, with relatively low losses.
  • Dynamic pricing and user-side load shifting (EV charging, appliances, HVAC preheating/precooling) are seen as critical complements to storage.

EV Batteries, V2H/V2G & Off‑Grid Aspirations

  • EVs are recognized as huge latent storage pools; standards for bidirectional charging (V2H/V2G) are just emerging.
  • Some already use V2L/V2H for backup instead of stationary batteries.
  • There’s tension between romantic off-grid independence and the broader systems problem; many argue the real optimization is grid-connected with substantial self-consumption, not full isolation.

Resources, Recycling & Long-Term Sustainability

  • Concern raised about material limits for PV and batteries; responses emphasize:
    • Panels mostly use abundant materials, silver being the main constrained input,
    • Batteries can and likely will be recycled as economics shift,
    • Flow of materials through PV+battery systems is small relative to existing construction waste streams.