One law, every kind of utility
Missouri's Net Metering and Easy Connection Act, Section 386.890 RSMo, establishes standards for interconnecting qualified net metering units with generating capacity of 100 kW or less with the distribution systems of electric utilities.
The law applies to all regulated electric utilities, to municipal electric utilities and to rural electric cooperatives, which are required by the law to adopt policies establishing a simple contract to be used for interconnection and net metering.
That is the opposite of the pattern in most states, where municipal utilities and cooperatives sit outside the statewide rule and set their own terms. In Missouri a figure from a neighbouring town on a different utility is a more reasonable starting point than it would be elsewhere.
It does not mean every utility is identical, since each adopts its own policies under the law. Ask your own utility for its net metering policy in writing rather than assuming the statutory minimum is exactly what you get.
Retail within the period, avoided cost at year end
Standard residential tariffs apply a retail-rate offset for in-period consumption, with year-end surplus reconciled at avoided cost rather than at the retail rate.
Read that as two different values for the same kilowatt hour depending on what happens to it. Generation that offsets your consumption within the period is worth the retail rate. Generation that survives to the annual reconciliation is worth considerably less.
The design conclusion follows directly: build to your consumption rather than beyond it. A system deliberately oversized to bank credit is producing electricity that will ultimately be settled at avoided cost, which is a poor use of capital.
Ask your installer what percentage of your annual usage the proposed system covers, ask for the design to be built from your last twelve months of bills, and ask specifically how the year-end reconciliation was treated in the savings projection.
The response times the law gives you
For systems of ten kilowatts or less the application process uses an all-in-one document that includes a simple interconnection request, simple procedures and a brief set of terms and conditions. That is a deliberately light-touch route for ordinary residential systems.
The utility is required to review and respond within 30 days of receipt for systems of ten kilowatts or less, and within 90 days for all other systems up to 100 kilowatts.
Those are useful numbers to hold a project against. Ask your installer the date the complete application was submitted, then you know when a response is due rather than relying on a general assurance that things are progressing.
Ask for the expected date of permission to operate rather than the installation date. Panels on a roof are not yet a system that offsets anything, and the gap between those two milestones is where most of the frustration in a solar project lives.
Building the number from confirmed pieces only
Three things people expect in Missouri are either gone or unreliable, and a quote built on any of them overstates your return. The 30 percent federal Residential Clean Energy Credit under Section 25D expired for property placed in service after December 31, 2025, so a cash or loan purchase now receives no federal credit.
Utility solar rebates historically existed here but have largely been discontinued. If a rebate appears in a quote, confirm directly with your own utility whether it is currently open, what it pays and whether funding remains, before you sign anything.
And the property tax exemption most guides still list was held unconstitutional by the Missouri Supreme Court on August 9, 2022. Ask your county assessor how residential solar is being assessed at your address rather than assuming an exemption applies.
What does exist is net metering under the Easy Connection Act and the electricity you stop buying. Ask any installer to rebuild the arithmetic from those two things alone, and treat resistance to producing that version as informative in itself.