Using a Solar Diverter with an EV Charger: Pros & Cons

As more Irish homeowners combine solar panels with EV chargers, a key question arises: should you add a solar diverter to the mix? A solar diverter helps maximise your self-consumption of solar energy by sending surplus electricity to heat your water tank instead of exporting it back to the grid. But when paired with an EV charger, the picture becomes more complex. Here’s a breakdown of the pros and cons to help you decide whether a solar diverter makes sense for your setup.

✅ Pros of Using a Solar Diverter with an EV Charger

1. Maximise Self-Consumption

Without a diverter, excess solar power that isn’t used immediately is often exported to the grid. A diverter ensures that surplus electricity stays in your home, either charging your EV or heating your water. This reduces reliance on the grid and increases your energy independence.

2. Reduce Energy Bills

By prioritising hot water heating before exporting, you avoid paying for gas or electricity to heat water. When combined with an EV charger, this means you can cover two of your largest household energy demands, transport and hot water, using free solar power.

3. Take Advantage of SEAI Grants

SEAI offers grants for both solar PV systems (up to €1,800) and home EV chargers (€300). While the diverter itself isn’t grant-funded, pairing it with these incentives makes a more efficient long-term investment.

4. Works Seamlessly with Smart Chargers

Some EV chargers (like Zappi by Myenergi) are designed to work with solar diverters. They can intelligently balance where excess solar energy goes, your car or your immersion, without manual switching.

❌ Cons of Using a Solar Diverter with an EV Charger

1. Competing Priorities for Solar Power

On sunny days, you may not generate enough surplus energy to heat your water and charge your EV simultaneously. In this case, your diverter may send power to the immersion when you’d prefer it go to your car.

2. Longer EV Charging Times

Solar diverters often prioritise water heating first. That means your EV may charge slower or only when hot water demand is met, limiting how much solar you can actually put into your vehicle.

3. May Reduce Export Tariff Earnings

Ireland’s feed-in tariff means you now get paid for electricity exported to the grid. By diverting more solar to hot water instead, you may reduce the amount you can sell back, potentially lowering income.

4. Added Upfront Cost

A solar diverter is an extra piece of hardware that can add €500–€1,000 to installation costs. While it can pay off over time, this upfront expense should be weighed against the potential return.

⚖️ Is a Solar Diverter Worth It with an EV Charger?

If your home uses a lot of hot water and your EV charging needs are modest (for example, short commutes), then a solar diverter can make your system more efficient and reduce bills.

However, if your priority is maximising EV charging from solar, you may prefer to let your charger take surplus energy first, or consider adding a home battery. A battery can store excess solar for use in your car or home later, offering more flexibility than a diverter alone.

🚗☀️ Bottom Line

A solar diverter with an EV charger can make sense for many Irish homes, but it depends on your household’s priorities. At WattCharger, we design systems around your lifestyle, balancing hot water, EV charging, and energy export so you get the most from your solar investment.

👉 Thinking of combining solar and EV charging? Get your free quote today and see how WattCharger can help you power your home and car the smart way.