Establish your county before you file anything
Grand Prairie extends across Dallas, Tarrant and Ellis counties, and residents deal with the appraisal district for the county their property actually sits in rather than the one the city is most associated with.
That is not obvious from an address. The city is long and narrow, running between Dallas and Fort Worth, and the county boundary does not follow any landmark a resident would notice.
Each appraisal district publishes an address search, so establishing which one covers you takes a couple of minutes and settles the question definitively. Do it before you need the answer under time pressure.
Write the answer down with your project paperwork. You will need it again for the exemption filing, and possibly for permitting questions, and it is the sort of detail that is easy to look up once and then misremember.
The exemption itself, and the deadline
Texas Tax Code Section 11.27 exempts 100 percent of the appraised value that an installed solar energy device adds to your home. It is a genuine benefit and it is not applied automatically.
Form 50-123 must be filed with your county appraisal district, and the deadline for the current tax year is generally 30 April. Nobody files it on your behalf unless you have specifically arranged that.
Ask whether your installer assists with the filing, and ask which appraisal district they intend to file with. An installer working across the whole metroplex may default to Dallas County without checking, and for a Tarrant or Ellis County address that is the wrong office.
Calendar the deadline yourself regardless of the answer. An exemption you qualified for and did not claim is money lost to paperwork rather than to economics.
The other decision, which is your electricity plan
Grand Prairie sits in the deregulated Texas market, so there is no statewide net-metering mandate and what you are paid for exported solar comes entirely from the retail plan you have chosen.
Plans vary enormously. Some buy back exports generously, some modestly, and some not at all, and two identical systems on the same street can return very different amounts purely because of the contracts behind them.
PowerToChoose.org is the state-run comparison site and is the right starting point because it is not selling you anything. Work out which plans at your address buy back exports and on what terms before accepting anyone savings projection.
Compare the buyback rate and the energy rate together rather than chasing the highest buyback. Across a year most households buy far more electricity than they export, so the rate you pay usually moves your bill more than the rate you are credited.
What the federal change did to the numbers
The 30 percent Residential Clean Energy Credit under Section 25D expired for property placed in service after 31 December 2025, so a cash or loan purchase now receives no federal credit.
A great deal of published material and calculator logic was written while that credit existed and has not been revised, so a quote that still applies it is overstating your return substantially.
Section 48E survives at 30 percent for third-party owners under leases and power purchase agreements, so such a provider may claim it and reflect part of that value in the rate they offer. What they claim and what reaches you are separate questions.
That makes the property tax exemption a larger share of what remains than it used to be, which is another reason to get the county question right rather than treat it as a detail.