The Problem
A home with solar panels deals with two companies that do not talk to each other. The solar company's app shows what the panels produce and what the house uses. The utility decides what all of that is worth: it sets the rates, banks credits for extra power, and sends the bill. A homeowner who wants to know whether they are on the right rate plan, or how close the system is to paying for itself, has to piece the answer together from both.
What We Built
A dashboard that does the piecing together. It collects a fresh reading from the solar equipment every 15 minutes, combines it with the monthly utility bills, and shows the full financial picture in one place: energy made and used, credits banked, what the bill would be under each available rate plan, and progress toward paying off the system.
How Maine's Solar Billing Works
How credits are earned, banked, and used up has an enormous effect on what a solar household pays. The rules are specific to Maine and to Central Maine Power, and understanding them is the only way to see how solar is changing your bill.
Credits expire, oldest first
Extra power sent to the grid earns credits, and in Maine a credit lasts 12 months. One earned last July is gone this July if it has not been used. The dashboard tracks each month's credits separately, so it can show what is about to be lost.
Same usage, three prices
CMP offers three rate plans, and each prices the same month of electricity differently. Some charge more at busy times of day. The dashboard works out every month's bill all three ways, using the household's real usage.
No AI, on purpose
These questions have exact answers, so the dashboard calculates them. When a published rule already settles the matter, a calculation is the right tool and an AI model is not.
What It Does
- Updates itself every 15 minutes with what the panels are making and the house is using
- Charts energy by day, week, or month
- Tracks banked credits and when each batch expires
- Compares the monthly bill under each of CMP's three rate plans
- Shows progress toward paying off the system, counting tax credits and bill savings
Screenshots
Behind the Build
For technical readers.
The dashboard ingests 15-minute interval data from the SolarEdge API and combines it with monthly utility billing records to model energy costs across CMP's Rate A, Electric Technology, and Time-of-Use structures. Credit tracking implements first-in, first-out queue logic to match the 12-month rolling expiration under Maine's Net Energy Billing program. Pattern analysis shows how consumption and generation shift across hours, days, and seasons, and feeds the rate plan comparison.