About SolarControllerFinder

SolarControllerFinder is what PCPartPicker would be if it focused on off-grid solar. Enter your panels and battery, and we run the wiring math — NEC 690.7 cold-weather Voc derating, 690.8 ampacity limits — to tell you which charge controllers actually work together. Honest recommendations, no incompatible upsells.

The non-negotiable principle

Advertisers can pay for placement, but not for compatibility. This is the trust rule the entire site is built around. Our rules engine determines whether a charge controller is compatible with your panels and battery using physics and NEC code — full stop. No advertiser, sponsor, or partner can pay to override an incompatibility flag. They can pay to be the primary purchase link for a compatible product. Two different things.

What we're optimizing for

• Compatibility over conversion. A bad system match wastes hundreds of dollars and burns out components. Our rules engine catches the mistakes before you buy.
• Education over engagement. The guides exist so you can understand the math yourself. We'd rather have one informed user than ten flummoxed ones.
• State context over generic advice. California's NEM 3.0 fundamentally changes the solar economics; Arizona's heat changes battery chemistry choices; Oregon's cloud cover changes array sizing. Generic "solar advice" misses all of this. See our state guides.

Affiliate disclosure

SolarControllerFinder is independent and free to use. We make money when readers click outbound links to merchants (Amazon, Renogy, Signature Solar, etc.) and end up buying. Affiliate relationships do not influence which products we mark compatible — that's what the rules engine does, and it doesn't know which vendors are paying us.

What affiliate relationships DO influence: which vendor's link is shown as the "primary" buy button for a compatible product. We disclose this on every product listing and per FTC guidance.

If a recommended controller doesn't have any affiliate program (Victron is one example — they don't pay anyone), it still shows up exactly the same as affiliate-paying brands. Recommendations would be identical with zero affiliate revenue.

How the rules engine works

The compatibility math lives in lib/rules.ts — a pure TypeScript function with no framework dependencies. It runs four checks for every (panel, battery, controller) combination:

1. Cold-weather Voc derating (NEC 690.7) — does the controller handle the worst-case panel voltage?
2. Current limit (NEC 690.8) — does the controller have enough amps for the battery voltage you've chosen?
3. Battery chemistry support — does the controller's charge profile actually fit your battery type?
4. Voltage matching — does the controller support your battery's nominal voltage?

Each check returns pass/warning/fail with a plain-English reason. The combined scorecard is what you see in the builder.

Who built this

Spencer Stone (SaintOne Solutions). DIY solar enthusiast and independent developer. Reach out at spencerdstone@gmail.com with corrections, feedback, or product additions.

Other projects

Also building EV Quiz — the same compatibility-first ethos applied to electric vehicles. If you're considering whole-home electrification (solar + EV), the two tools pair well.