The Solar-to-Wheels Microgrid
Solar, storage and chargers sharing a connection aren't a microgrid until an energy management system coordinates them. The timing problem is what makes or breaks the economics.
A site with solar panels, a battery and EV chargers is not automatically a microgrid — it's three separate pieces of equipment that happen to share a connection point, unless something is actively coordinating them. The difference between those two states is entirely down to the energy management system sitting in the middle, and it's the difference between a site that manages its own peaks and one that simply relocates them.
Government analysis has been explicit that solar-plus-storage can support charging, reduce grid dependence, and in some cases reduce the size of connection a site needs to request in the first place — which changes the economics of a project before a single kilowatt of electricity is used.
This briefing sets out the physical architecture, the timing problem at the heart of it, and the commercial models that make it work for different kinds of sites.
Five components, one coordinating layer
Figure 1. Solar and the battery feed the EMS; the EMS decides, moment to moment, how much of that goes to chargers, how much is stored, and how much crosses the grid connection in either direction.
Daytime coincidence: workplace vs domestic
Solar peaks at midday. Most home charging happens after dark.
A workplace car park with solar canopies and daytime dwell times is close to an ideal match — panels generate through the working day, cars are parked and charging through the working day, and a large share of that generation can go straight to wheels without ever touching a battery or the grid connection. A domestic driveway is the opposite case: solar generates at midday while the house is empty and the car is out, then the car comes home and starts charging just as generation is falling away.
That mismatch is exactly what a battery is for in the domestic case — storing midday generation to release it into the evening charge — and exactly what makes workplace and destination charging a structurally easier proposition for solar coupling than most home installations, battery or not.
Peak shaving and capacity management
The EMS's second job, alongside matching generation to load, is keeping the site's demand on the grid connection within whatever limit was agreed at design stage. A battery that discharges during a high-demand moment — several chargers ramping up at once — can shave the peak the grid connection actually sees, which matters because connection capacity is often the single most expensive and slowest-to-change constraint on a site's growth.
Done well at the design stage, this can reduce the size of connection a site needs to request in the first place — turning what would have been an expensive, multi-month grid upgrade into a smaller connection paired with smarter on-site management.
Self-consumption vs export
Every unit of solar generation a site uses itself avoids both the wholesale cost of imported electricity and, depending on tariff structure, network charges — which is usually worth more than the same unit sold back to the grid at an export tariff. That single fact is what makes coordinated self-consumption, not maximum export, the usual design priority for a solar-plus-storage-plus-charging site, with export treated as what happens to genuine surplus rather than the primary revenue plan.
Where a true microgrid differs from simple co-location
Simple co-location
Solar, battery and chargers share a connection but all still depend on the grid being live — a grid outage takes the whole site down with it.
True microgrid
The site can disconnect and continue serving critical loads from its own generation and storage — a genuinely different, more complex, and more expensive engineering proposition.
Commercial models by site type
Fleet depots get the clearest payback — predictable dwell times, daytime or overnight charging aligned to operational hours, and a strong incentive to avoid expensive grid-connection upgrades as fleets electrify. Workplaces and retail parks benefit from the daytime coincidence directly. Public-sector estates — often long-term asset holders with sustainability mandates — are increasingly the ones willing to fund the capital cost for a payback measured in years rather than quarters.
The 2026 flexibility roadmap explicitly links public support for solar and batteries with flexible tariffs — which means the sites that design solar, storage and charging as one coordinated system now are the ones best placed to capture that support, rather than retrofitting coordination onto equipment that was procured separately.
How a read moves across the estate
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Chris Gales
Chris Gales leads CEHG. He converts complex technical and commercial choices into clear decisions and dependable outcomes for utilities running connected device estates at scale.
He writes these field notes from the practice — on bearer migration, smart metering architecture, procurement and operations — to help estates start counting down early.