Solar Carport and Chargers: Turning a Company Car Park into an Energy Asset

A company car park is usually a pure cost: asphalt that only gets more expensive. With a photovoltaic carport and a few charging points it starts producing power, protects cars from hail and sun, and becomes an argument for clients and staff. Here is the engineering behind it.

How much power a solar carport delivers

A carport over 10 parking spaces holds roughly 30–40 kWp, which in Bulgaria produces about 37,000–50,000 kWh per year. That is enough to cover part of the building and charge serious mileage: at an average 18 kWh/100 km, the same energy equals over 200,000 km of electric driving a year.

Three advantages over a rooftop system that clients underestimate:

• Tilt and orientation by choice — the structure is designed facing south at the optimal angle instead of following the roof.
• No building structural issue — the load sits on its own columns.
• Double benefit — shade and protection for the cars; a car parked in the sun spends its own battery on air conditioning.

How to add chargers without raising your connected power

Dynamic load management measures the site's total consumption and gives the chargers only the free headroom — so four 22 kW points can live behind a connection that could never carry them simultaneously. The standard allows down to 6 A per point, so the system stretches charging rather than stopping it.

Why this matters for costs: moving from the 16–50 kW band into 51–100 kW multiplies the one-off connection fee roughly 2.5× at the northern and southern distributors. Separately you pay network access on every contracted kilowatt — at northern distributor tariffs that is about €6.3 per kW per year, so +100 kW costs around €630 a year even if you never draw an extra kilowatt-hour.

And one more rule that surprises people: exceed your contracted power for two consecutive months and the supplier may adjust it administratively — with all the resulting charges.

What charging power you actually need

Choosing between AC and DC is a choice about dwell time, not speed. Roughly, for a car with a 60 kWh battery:

• 7.4 kW (AC, single-phase) — about 8–9 hours. For full-day staff or hotel guests.
• 11 kW (AC, three-phase) — about 5.5–6 hours. The most common ceiling of the on-board charger in the cars themselves.
• 22 kW (AC) — under 3 hours, but only if the car has a three-phase on-board charger; many models do not.
• 50–150 kW (DC) — about 25–35 minutes to 80% at 150 kW, correspondingly longer at 50 kW. For roadside sites, restaurants and retail.

The practical conclusion: for offices and hotels DC rarely makes sense — more 11 kW points serve more people for the same money.

The role of the battery: cheaper than a thicker cable

A battery system flattens the peaks, so brief simultaneous charging does not eat into your contracted power. It is the same mechanism we described in our article on BESS for business — here the peak is simply called "three cars arrived at once".

The combination works in reverse too: by day the panels charge the battery and the cars, by evening the battery powers the building. In dedicated surplus-charging mode, modern chargers start at around 1.4 kW of spare solar power, and in blended mode at under half a kilowatt.

What not to underestimate on the coast

The coastal climate shortens the life of an under-specified structure and poorly chosen equipment. For sites in Varna and along the Black Sea we plan for:

• Corrosion protection of the structure — the same approach we describe for hybrid systems by the sea.
• Ingress protection of the chargers — outdoor installation demands resistance to dust, water and impact.
• Cable runs — the distance from the board to the chargers goes straight into the price; early routing saves thousands.
• DC fault protection — charging points require a specific type of residual current protection, often omitted from quick quotes.

Where a project starts

Sizing starts with your consumption profile and the number of cars that will actually charge — not with a manufacturer's catalogue. We do the analysis, design, installation and 24/7 monitoring as one obligation.

Review the regulatory requirements for car parks too, and if you want an indicative price right now — the calculator gives you a figure in two minutes.

Request an analysis for your car park — free and without obligation.