• Solar Expert

Solar Charged EV's- with the Sun

So you are a Electric Vehicle owner or looking to become one, and have interest in using solar energy to drive for free, or theoretically anyways. Many customers owning EV's are asking the same question.

How to charge an EV with solar.

All of the questions we are most often answering are great questions, and we are here to answer them. The questions most often asked are:


How many panels do I need to charge my electric vehicle? Like a Tesla, Nissan Leaf, Rivian, etc?

The amount of solar needed is often a question that is difficult to answer unless we know how much driving you do during the year. But let's assume you have a Tesla Model 3 with the 100kWh battery and drive 300 miles a week.


That is about the maximum distance of that battery pack, so if your electricity costs are ~$0.14/kWh, and the battery takes 100 kWh to charge, your charge cost is $14.00 and that makes your per mileage cost around $0.04/mile.


For the month, you would need 400 kWh of solar energy production to meet 100% of your driving needs. For the year you would need 4,800 kWh of solar production. In Minnesota and Western WI, 1kW (3 panels) of solar produces around 1,300 kWh's of electricity.


To meet 100% of the example above you would need 3.7kW solar system to offset your driving needs. A typical home solar system is around 7-9kW. So, not much is needed to offset typical EV driving for the year, making EV's a great economical choice.


Faraday Solar Designed Carport- Example of a 8.5kW for two cars


How many batteries am I going to need for my solar?

This is an often asked question, and the answer is pretty simple. No batteries are necessary for a solar pv system that is grid connected. It is actually not advantageous to have batteries in the MN solar market due to the way the rate structures are with the utilities.


As an example, with Xcel energy in MN, residential customers have a mostly flat kWh rate and its best to simply produce the energy you use and if you cannot use it the time and day you produce it. Net metering allows you to sell it to the utility to offset your future needs. In this case the utility is your battery.


In markets that have time of day billing batteries make sense, because you can store the energy you produce during lower billing rates, then sell it when it's most expensive, which is also when the utility needs it the most.


Does the solar energy have to be compatible with my EV charger?

Nope, because we are producing electricity that simply dumps all its solar energy onto the grid and your homes electrical system. However, if you are in the planning stage or sooner on your EV and Solar quest. SolarEdge, a leading solar inverter manufacturer has made a EV charger integrated into its solar inverter and this saves you money as the cost increase is for the EV integrated inverter is minimal vs. two single pieces of equipment. Plus because its solar equipment, say hello to a 30% federal tax credit. Your welcome!


Will I be able to switch between the solar and the grid if needed?

No need. Electron flow between your solar, electric panel, the utilities power plant, and your awesome new EV happens like magic. If you wanted to have some emergency backup options, we would suggest a generator from Generac®. That way if the grid goes down for an extended time, you can still get around in the case your awesome new EV is low on charge. In the case of a generator, they normally have automatic transfer switches that automatically switch power from the utility to the generator. This helps protect the linemen and women working on the utility grid, plus its code.


Typical public EV charger


What happens if the Grid goes down?

As discussed in above, you're likely to not have any batteries, so if the grid goes down so, does your EV charger and grid tied solar system. Your best bet as previously discussed is to have a generator for backup scenarios.


In the future, there is talk and planning, to develop a far smarter electric system that is symbiotic between batteries in our EV's, batteries in our homes, your solar system, etc. that will have small "islands" of power between neighborhoods that will accomplish this without the need for individual home generators. But for now, if you want back-up power in MN, I recommend a generator.


Do I need to get a new or special Electric Vehicle charger?

If you already have a electric vehicle charger, then nothing is needed other than a new solar array. The new solar system integrates with your EV chargers existing electrical system to supply power. If your looking into getting an EV charger but will wait on the solar, Charge Point is a good resource.



Solar and EV's go together so well and if your buying a home solar system in conjunction with or before your EV, then we suggest reaching out to Faraday Solar for your free analysis. Thanks for reading.

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