Background primer

Solar + storage, explained

How residential solar panels and battery systems work, and why optimizing them is hard.

Fundamentals

How solar panels work

Solar panels convert sunlight into electricity through the photovoltaic effect.

Sunlight hits the panel

Photons strike silicon cells.

Electrons get excited

The energy knocks electrons loose.

Electricity flows

The moving electrons create current.

Power your home

An inverter converts it to usable AC.

The catch

Solar panels only generate power when the sun is shining. No sun, no power, which is exactly why batteries matter.

Storage

Why we need batteries

Panels generate the most power at noon, but a home often needs the most electricity at 7 PM, the timing mismatch problem. A battery is essentially a water tank for electricity: solar fills it, the home drains it, and you choose when to do each. The key specs:

Capacity: Energy held (typically 10–15 kWh).
Power: Charge/discharge rate (typically 5 kW).
Efficiency: Energy retained (typically 85–95%).
Lifespan: Charge cycles (typically 5,000–10,000).

The hard part

Why this is hard for computers

Every 15 minutes, the system decides whether to use, store, sell, or buy power. The factors stack up fast.

Time-of-use pricing

Peak (5–9 PM) $0.30–0.40/kWh, off-peak (11 PM–6 AM) $0.10–0.15/kWh, solar hours sometimes negative.

Weather uncertainty

Will tomorrow be sunny or cloudy?

Usage patterns

When will the household actually use power?

Battery constraints

Can't charge/discharge too fast or exceed capacity.

Efficiency losses

Every time you store energy, you lose some.

Total possible schedules

Over 10¹⁰

(10 billion) combinations for a single day

Now you know the basics

See how I am tackling it

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