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Concepts · Chapter 17

Why local control matters

Cloud lock-in, subscriptions, outages — and what real independence buys you. The motivation before the mechanics.

Updated: 2 min read Deutsch →

Before Modbus and Home Assistant, the question: why control it yourself at all? The answer decides how much the platform choice should be worth to you when buying.

What "local control" promises

Local control means PV, battery, heat pump and car run through a system you own — ideally Home Assistant on your own network — instead of each manufacturer's cloud. You read the data yourself and issue the commands yourself.

The three risks of cloud dependency

  1. Lock-in. If monitoring and control only run through the vendor's app, you're tied to its ecosystem. Switching or integrating across brands becomes hard or impossible.
  2. Subscription risk. Some features (e.g. automatic control by dynamic tariff) drift behind a paid cloud tier. Locally you do the same for free.
  3. Outage & discontinuation. Servers can fail, services can be shut down. A local system keeps working even if the maker turns off the cloud.

What independence gives you concretely

  • Your own dynamic-tariff logic: charge the battery when power is cheap; run the heat pump when there's sun or cheap grid power.
  • Cross-vendor coordination: your PV brand doesn't have to talk "natively" to your heat-pump brand — Home Assistant/evcc bridge them.
  • Full transparency: you see every number in real time, on your own network, without a detour through someone else's servers.
  • Privacy: your consumption data stays at home.

The honest flip side

Local control is not a must. It brings effort: setup, a small server (e.g. a Raspberry Pi), occasional maintenance after firmware updates. If you don't want that, the vendor app serves you fine — but you accept the three risks above. It's a deliberate trade-off, not a requirement.

Why the buying decision hinges on this

If local control is your goal, the inverter platform becomes a real selection criterion — not just price and battery size. Some brands make it easy, others fiddly. That's exactly what the next chapters examine.

In short: local control protects against lock-in, subscriptions and cloud outages, and unlocks your own tariff/surplus logic — for some setup effort. If that matters to you, choose the platform for it.

Next, the tool for judging that: the controllability checklist.

In this section

Energy basics: kW, kWh, and what "kWp" actually means The single most common mix-up in offers and conversations, cleared up once — because everything else builds on it. How a PV system works From sunlight on the roof to power at the socket — the chain in four steps, and what actually drives yield. Understanding modules Mono or bifacial, cell quality, and the difference between product and performance warranty — without the marketing. Battery basics Nominal vs usable capacity, LFP vs NMC, depth of discharge, and sizing the battery to your array. How a heat pump works A fridge, thought about backwards — why a heat pump turns 1 kWh of electricity into several kWh of heat, without breaking physics.