ComEd has a filed rider that pays a rebate on energy storage paired with solar. It is Rider SPWS, it sits in ComEd's tariff book, and it became effective in the spring of 2026 under a compliance filing following the state's recent energy legislation.
If a battery is being proposed to you in ComEd territory, this rider is probably part of the arithmetic, and it is worth understanding what it does and, more usefully, what it does not do.
What the rider is hooked to
Reading the operative definitions, the rebate attaches to a storage facility paired with a distributed solar generating facility, using a smart inverter meeting the current interconnection standards. Those are the conditions that put a project inside it.
Two things are notably not in it, and both matter because they are commonly assumed.
It does not require the battery to charge only from solar. The rider's own definition of an eligible storage facility is written in charging-source-neutral terms, and it explicitly contemplates the storage participating in wholesale frequency regulation, which is not something a solar-only battery can do. So if someone tells you the ComEd rebate is why your battery cannot charge from the grid, that is not where the restriction comes from.
It does not decide whether the battery pays. It is a reduction in capital cost. That is a real and sometimes decisive thing, and it is a different question from whether the asset earns anything once installed.
Where the solar-only restriction actually comes from
The constraint people attribute to SPWS lives in Illinois Shines, the state's renewable energy credit program. Its guidebook sets out how a system with a battery must keep grid-charged energy out of the credited solar production, and one of the compliance paths does that by locking the inverter to solar-only charging for the life of the credit contract.
That path is the cheapest to build and it is commonly the one elected, which is why the restriction feels universal. It is not universal. It is a design choice, made once, that binds for fifteen to twenty years, and it is worth knowing which one your proposal has taken before you sign it.
The distinction is worth this much space because it has a large economic consequence, covered on that page.
Why we publish no rebate figure here
We do not have the rebate's dollar value, caps or application mechanics confirmed first-party, so we are not going to print them. A number quoted from memory or from an installer's slide is exactly the kind of figure that gets stale, gets misquoted, and ends up anchoring a decision it should not.
Ask for the current filed rider and the current program materials, and ask specifically what is capped and what is first-come. Incentive programs with budgets behave very differently at the start and the end of a funding period, and that timing is often worth more to a project than the headline rate.
The order that keeps you out of trouble
Feasibility first, incentives second. This is the whole argument and it is unpopular with everyone selling hardware.
A rebate lowers what a battery costs. What a battery earns on a commercial account in ComEd territory is mostly the demand charge it avoids, and that depends entirely on the shape of your peaks: how far your highest qualifying half hour sits above your second-highest, how often the peak recurs, and whether the battery can actually be charged and ready at the moment it matters.
A site whose peak is one sharp event a month is a good candidate. A site that runs flat against its own ceiling all day is not, and a fully rebated battery on that site is still a bad investment. The rebate cannot fix a load shape.
So the sequence is: establish whether the peaks are shavable, size the battery against the measured peak rather than the proposed one, then apply the incentives to a project that already stands up. Doing it the other way round produces projects justified by their subsidy, which is how a twenty-year decision gets made on the strength of a one-time cheque.
The feasibility question comes first, and it is answerable from your own bill and meter data before any program is applied to.
What is ComEd Rider SPWS?
A filed ComEd rider providing a rebate for energy storage paired with distributed solar generation, effective in 2026 under an Illinois Commerce Commission compliance filing.
Does Rider SPWS require the battery to charge only from solar?
The rider's eligibility definition is not written in charging-source terms, and it contemplates participation in wholesale frequency regulation. The solar-only requirement people associate with Illinois batteries comes from a compliance path in the Illinois Shines credit program, not from this rider.
Do I need solar to get a ComEd storage rebate?
Rider SPWS is a solar-paired rebate, so it attaches to storage installed with a distributed solar generating facility. Illinois also has standalone storage support that does not require solar; they are separate mechanisms and should be evaluated separately.
Should the rebate decide how large a battery to install?
No. Size the battery against the peak it has to shave, measured from your own interval data, then apply the incentive. Sizing to maximise a rebate produces an asset that earns less than it cost even after the rebate.