Flexible Load vs. Batteries for Curtailment
When a site is curtailing energy, there are really only two things you can do with the surplus: store it and sell it later, or use it now. Batteries do the first; a flexible load does the second. They are often framed as rivals, but they solve slightly different problems.
What batteries do
A battery time-shifts energy: it charges when there is surplus and discharges when prices are higher, so its value depends on the spread between cheap and expensive hours — and on the grid being able to take the energy when you discharge. Batteries are proven and flexible, but they carry significant capex, they degrade with every cycle, and they only pay when the price arbitrage is genuinely there. If the grid is congested when you want to discharge, or the spread is thin, the case weakens.
What a flexible load does
A flexible load does not store anything — it consumes the surplus on site, the moment it appears, and converts it directly into revenue. Because the energy would otherwise have been curtailed, its marginal cost is effectively zero, and there is no round-trip loss and no export required. It does not depend on price spreads or on the grid being able to absorb anything later. Its job is simply to put energy that has nowhere to go to work immediately.
When each makes sense
The right tool depends on why the energy is stranded:
- Batteries fit when there is a real price spread to capture, the grid can absorb the stored energy later, and storage is supported in your market.
- A flexible load fits when the connection is constrained or undersized, the site is off-grid or waiting to connect, curtailment is persistent, or the surplus simply cannot be re-exported at a useful price.
They can work together
This is not always an either/or. A battery can smooth supply and capture arbitrage, while a flexible load mops up the surplus that still cannot be exported even after the battery is full. On a heavily curtailed site, the two can be complementary rather than competing. The key question is not which technology is better in the abstract, but which one — or which combination — turns the most of your otherwise-wasted energy into revenue. That is exactly the kind of thing worth modelling per site.
Frequently asked questions
Is a flexible load better than a battery?
Neither is universally better. A battery shifts energy in time to re-sell it; a flexible load uses it on site now. The right choice depends on whether the grid can take the energy later and at what price.
Can I use a battery and a flexible load together?
Yes. They are complementary — a battery can smooth supply and capture arbitrage, while a flexible load absorbs surplus that still cannot be exported even after the battery is full.
Why not just add a bigger battery?
If the grid still cannot absorb the energy, or prices are poor when it can, storing more of it does not create value. Using it on site does.
Does a flexible load degrade like a battery?
The hardware has its own lifecycle, but there is no round-trip energy loss and no charge-cycle degradation the way there is with a battery.
Have a curtailed, capped or off-grid site?
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