MV-513 · Phase 4 Advanced

Renewables, BESS & EV MV Integration

Q: How much does solar export raise the voltage?

Approximately ΔV% = (P x R + Q x X) / V² x 100, using the feeder resistance and reactance to the point of connection. For 1.5 MW on 11 kV through 1.2 ohm, the rise is about 1.5% at unity power factor.

Q: Can a battery avoid a transformer upgrade?

Often yes. If the peak above the transformer rating is short, a battery can supply it and recharge at off-peak times. Check the energy above the limit and the battery recharge window.

Q: Does reverse power flow damage transformers?

Distribution transformers can generally carry reverse power, but protection, tap settings, metering and the upstream network must be checked, and some utilities limit export at each connection.

Q: What are volt-var and volt-watt modes?

Inverter control modes that absorb reactive power (volt-var) or reduce active power (volt-watt) as the local voltage rises, to keep it within limits. AS/NZS 4777.2 requires them in Australia.

Put solar, a battery and EV chargers behind one MV connection and play a full day in 3D. The battery soaks up midday solar and shaves the evening peak. Then check how much the export raises the voltage at the connection point and what the local rules expect.

In short

Solar PV peaks at midday while building and EV loads often peak later, so a battery can shift energy and cut the peak demand the transformer and utility see.
When generation exceeds load, power flows back into the MV network. Protection, metering and transformers must be suitable for reverse power.
Exporting power raises the local voltage by about ΔV ≈ (P·R + Q·X) / V². Absorbing reactive power (Q < 0) offsets part of the rise.
Inverter-connected generation must meet the local rules, such as DEWA's distributed renewable rules in Dubai, AS/NZS 4777 in Australia and New Zealand, and the AEMO generator performance standards for large plants in the NEM.
EV charging hubs add large, fast-changing loads. Smart charging and batteries can avoid upsizing the transformer and MV connection.

By Eng. Mannan Maqsood, Electrical EngineerPart of the MV Hub

4D Energy Day 3D 4D

Press play to run 24 hours. Panels glow with solar output, battery containers change colour with charge, cars light up while charging, and the cable flow shows import (orange) or export (green).

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Solar PV (MWp)

Battery power (MW)

Battery energy (MWh)

Building peak (MW)

EV chargers (MW)

EV pattern

Peak target (MW)

Transformer capacity (MVA)

Voltage Rise at the Connection Calc

Export through the MV feeder impedance pushes the voltage up. See how reactive power control keeps it inside the limit.

MV (kV)

Export (MW)

Feeder R (Ω)

Feeder X (Ω)

Inverter mode

Voltage limit (+%)

Grid Connection Rules by Region Reference

Region	Typical framework	What to check early
UAE (Dubai)	DEWA distributed renewable resources generation (Shams Dubai) standards, DEWA connection conditions	Approved inverter list, consultant and contractor enrolment, export metering, protection settings
Other GCC	National regulator and utility rules for small-scale and utility-scale PV and storage	Whether export is allowed, capacity caps per connection, metering and anti-islanding settings
Australia	AS/NZS 4777 for inverters, distributor connection rules, AEMO generator performance standards for large plant in the NEM	Export limits, volt-var and volt-watt settings, dynamic export, protection and SCADA for larger systems
New Zealand	Electricity Industry Participation Code Part 6 for distributed generation, AS/NZS 4777, lines company rules	Application category, congestion and export limits, inverter settings
Asia	National schemes such as net energy metering in Malaysia and the energy market rules in Singapore, utility technical requirements	Scheme eligibility, connection voltage, protection and power quality limits

Rules and schemes change often. Check the current documents from the utility or regulator before design.

How do solar, batteries and EV chargers change an MV connection?

A building used to be a simple load. With solar PV it becomes a generator at midday. With EV chargers its peak grows and moves to the evening or early morning. A battery sits between the two: it charges from surplus solar or off-peak grid power and discharges at the peak. Together they change the transformer loading, the direction of power flow, the protection settings and the voltage on the local MV feeder.

PractitionerCheck transformer and RMU suitability for reverse power, anti-islanding and protection grading with inverter fault contribution (usually only about 1.1 to 1.5 times rated current), metering for import and export, and the utility's limits on export and connection capacity.

How is a battery sized for peak shaving?

Start from the load profile: the power above the peak target sets the battery power (MW), and the area above the target sets the energy (MWh), plus allowances for round-trip efficiency (about 85 to 92%), depth of discharge limits and ageing. The simulator above shows when the battery runs out before the peak ends.

ExpertFor voltage rise, the X/R ratio of the feeder decides how effective reactive power control is. On cable networks with low X/R, absorbing reactive power helps less and active power curtailment (volt-watt) may be needed.

Regional notes

GCC

High solar resource and hot conditions favour PV with careful inverter and battery thermal design. Battery rooms need fire safety design to the local code and the maker's requirements.

Australia and New Zealand

High rooftop PV uptake means many distributors limit export or use dynamic export limits. AS/NZS 4777.2 sets inverter power quality response modes such as volt-var and volt-watt.

Asia

Schemes and connection requirements vary by country. Utilities publish technical requirements for solar and storage connections.

Test yourself

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Frequently asked questions

How much does solar export raise the voltage?