Solar Co-op

• 

  Solar Co-op

Inspiration

Sharing solar power also means sharing payment work. We built Solar Co-op to help community operators calculate bills, collect payments, pay producers and answer customer questions.

What it does

Solar Co-op connects meter data to a complete payment workflow: calculate → AI-prepared drafts → human approval → PayPal collection and payouts → reconciliation → dispute handling. Bills, payments and disputes keep separate statuses: closing a dispute never marks a bill paid.

How we built it

We used Next.js, React and TypeScript, with deterministic calculations in watt-hours and cents. Gemini uses constrained tools through the Vercel AI SDK to prepare drafts and investigate disputes. PayPal sandbox Invoicing and Payouts handle both payment directions, with status checks against one ledger. Render hosts the app.

Challenges we ran into

Total electricity consumption is not the same as shared solar energy. We built a meter-to-bill comparison chain and separated customer claims from payment evidence. We also added duplicate prevention, human approval and concurrency-safe payment limits.

Accomplishments that we're proud of

Our recorded workflow prepared seven consumer bills and three producer payouts; all ten matched the saved PayPal sandbox records. A separate fictional Haus 7 case demonstrates a saved real AI proposal explaining a correct bill. Judges can explore archived evidence and the guided case without credentials or live API calls.

What we learned

Code should calculate, AI should propose, and people should approve. Payment evidence does not prove that a meter reading is correct. Fees also matter: our modelled one-cent operator fee leaves only €0.19 after PayPal fees in June—not profit. Time savings remain unmeasured.

What's next for Solar Co-op

Test real settlement months with community operators, measure time savings and independently evaluate AI proposals. Before production: operator authentication, durable ledgers, meter-data corrections, payout recovery and confirmation of PayPal eligibility and the commercial operating model.

Built With

• google-gemini
• kokoro
• leaflet.js
• next.js
• node.js
• openstreetmap
• paypal
• paypal-payouts
• react
• render
• tailwindcss
• typescript
• vercel-ai-sdk
• vitest