Can an EV Owner Construct an Economical Solar Charger?

It’s a question that many electrical vehicle (EV) owners ponder: can I build a solar charger for my EV economically, instead of relying on commercially available options? The answer is a bit complex and depends on several factors.

The Feasibility of Building an EV Solar Charger

While DIY endeavors can be rewarding and gratifying, the reality is that building a solar charger for an electric vehicle (EV) is a multifaceted task. Factors such as regulations, the physical and practical aspects of building the system, and the potential return on investment all come into play. If you can’t see feasible ways to recoup your outlay for building and maintaining such a system, it might be smarter to opt for a commercially available one.

The Costs and Benefits

Let's break down the potential costs and benefits of building a solar charger for your EV.

Cost Calculation:

Solar power efficiency and the amount of driving you do each day are key factors in determining how many solar panels you would need. If on average you drive 50 miles a day, that equates to approximately 15 kWh of energy. An average panel in ideal conditions will generate about 0.15 kWh. Therefore, to replenish 15 kWh of energy, you would require:

100 panels to generate this in just 1 hour 50 panels to generate it in 2 hours 25 panels to generate it in 4 hours

However, EVs typically need to be charged during the day, which means they can’t be driven while the panels are generating electricity. To address this, a more practical approach is to use a solar battery that charges during the day and powers the car at night. In this scenario, you might only need about 12 panels and a solar battery.

Cost Estimate:

Estimating the cost of these panels and the battery is around ￡8,000. To recoup this investment, you’d need to generate approximately 110 megawatts (MW) of electricity for free to cover the installation cost. At a cheap rate, 110 MW of electricity is equivalent to using 15 kW of electricity per day. It would take about 20 years to break even on this investment. If you utilize the full capacity of your solar panels and battery daily (around 30 kWh) and completely offset grid electricity, you could potentially break even in 10 years, but still, it’s not a quick investment to recoup.

Market Trends and Price Drops:

This long payback period underscores the importance of reducing the costs of solar panels and batteries. When the payback period is within 3 to 5 years, the prospect of having a free-to-use charging station becomes much more appealing. As technology progresses and economies of scale are realized, the cost of solar panels and batteries are expected to decrease, making DIY solar chargers a more viable option.

Successful Implementations

Many EV owners in sunny regions, such as Southern California, benefit from home-solar systems. For instance, I have a small solar array and battery setup at home. This system, installed for earthquake resilience, has charged my Tesla multiple times, exercising my non-grid-connected system independently. Similarly, I have observed commercial charging stations, like the Baker California Supercharger station, which feature solar panels and batteries, utilizing a hybrid of solar, wind, and grid power.

When considering longer road trips, the energy used by the car can often be partially offset by solar power. This can be seen in areas like Death Valley, where multiple large solar farms are operational, generating significant amounts of solar power. While it's challenging to quantify the exact amount of energy used on a trip being sourced by renewables, the trend is clear: more solar installations mean more renewable energy for EV charging.

From an investment standpoint, constructing an EV solar charger might be a long-term project, but the future trends in solar technology suggest that it could become a more economically feasible option as costs continue to fall and performance improves.