Solar charging your EV, a smart idea but what to expect.
With the huge amount of sun hours at the Caribbean it makes sense to charge your EV with solar power. There are several options available:
- Option 1 – Solar panels and charging your car directly from the sun.
- Option 2 – Solar panels and a connection to the grid (without feeding back to the grid).
- Option 3 – Solar panels and a connection to the grid (with feeding back to the grid).
What is the best option for you?
Option 1
Mounting solar panels and charging your car directly from the sun.
The most obvious option seems to be installing solar panels and charge your EV directly from them.
However, as clouds pass by or when the evening falls in, the solar energy will fluctuate. Most EV’s cannot handle this so this option is not possible.
To overcome this fluctuation, you will need to install a storage battery. The battery will act as a buffer during fluctuations so the charging current to the car will always be the same.
If you want to charge early in the morning or at night, then you need your storage battery capacity to be larger than the battery in your EV. It is possible but the ROI (Return On Investment) will be very low due to the high costs of the batteries.
There is no connection to the electricity grid of the electricity company. That’s why this is called an “off-grid” solution. The advantage of “off-grid” is, that it will even work during an power-grid black-out. The disadvantage is that the overcapacity of your solar panels and/or storage battery is lost.
PRO
- You are independent of the energy company.
- Not connected to the grid.
- Works even with a power grid failure (blackouts).
- No solar tax.
- No limitations or rules from the energy company.
CON
- High initial costs.
- Fluctuating energy.
- Heavy load on the batteries.
- Surplus energy from the solar panels is lost.
Option 2
Solarpanels and a connection to the grid (without feeding back to the grid).
Instead of using a storage battery as a buffer, you can get additional power from the electricity company. If you do not return your surplus energy from the solar panels to the grid, the rules and the solar tax of the energy company don’t apply. You only take electricity; you don’t give back.
This option will use the maximum of the available solar power, and it is supplemented by the power of the grid when the solar panels don’t produce enough energy.
Your electricity bill will be higher, but you do not have to invest in the very expensive storage batteries and the power-feed to your car is stable.
During a power-grid blackout, you will not have the buffer of a storage battery causing the power-output of your solar panels to fluctuate; for example, when clouds pass by. Not every EV car can handle this.
You will need either a wall charger or an inverter which can handle both the input from the solar panels and the grid, without returning the solar surplus to the grid.
PRO
- Maximum charging power available, night and day.
- Lower investment (high ROI).
- No solar tax.
- No limitations or rules from the energy company.
CON
- Surplus energy from the solar panels is lost.
- Unstable power during power-grid blackouts as you have no storage battery.
Option 3
Solarpanels and a connection to the grid (with feeding back to the grid).
If you have a solar system installed which also delivers the surplus energy to the electricity company, you will receive a small compensation for each kWh you deliver to the grid. Every kWh you produce will count, either for your own use, or by getting money for each kWh delivered.
However, you might be restricted to the inspection, rules and regulations of the electricity company. And the solar tax will apply.
When you charge your EV in the daytime you will probably use all of the energy produced by the solar panels, and you won’t deliver energy back to the electricity company. So, in effect, you miss out on the compensation per kWh that the electricity company pays you.
When you charge the car when no sun is available, you will use electricity from the electricity company, who will charge you per kWh.
When you charge the car using electricity from your solar panels, it will cost you the compensation you would get per kWh from the electricity company.
If you cannot charge the car during the workday, you can consider charging during daytime on Saturday or Sunday and drive the whole week at very low costs. Nowadays, most EV’s have a battery capacity that can last you for the entire week on one charge, of course depending on your usage of the car.
Using this option, you do not need to install additional equipment such as batteries. Even a wall charger is not mandatory (you can use your household-outlets). So, the investment will be much lower, and for the overcapacity of the produced energy you will receive a compensation.
PRO
- Most effective use of all energy.
- Relative low investment.
- Medium ROI.
CON
- Restricted to the inspection, rules and regulations of the electricity company.
- Solar-tax apply.
- Amount of allowed solar panels may be limited by the electricity company.
Conclusion
Which option is best for you is something you have to decide yourself. What is your budget? What is your intention?
If you have enough budget and you want to be completely independent, an off-grid system including enough capacity on storage batteries might be your choice. The investment is high, but afterwards you get ‘free’ electricity for your home and EV, and you are your own electricity plant.
If you plan to charge your EV during the day, you can make maximum use of your solar panels. Option 2 might be the best solution for you. You will use the solar panels while it is producing the most energy, and it is backed-up by the (expensive) electricity of the electricity company in case the sun has disappeared. As you do not deliver back to the grid you do not receive any money for your surplus of energy. However, as you charge the car during the day, you would probably not deliver back anyways. You also save money as you don’t have to pay the solar tax.
If you will be charging during the night a lot, or your charging periods vary, then option 3 might be your best choice.
If you are not charging your EV during the day, the solar panels will produce a lot of surplus energy. For each kWh you deliver to the electricity company you will be paid a compensation. The produced energy is not lost, and you get paid for your surplus. On the other hand, solar tax will be charged, so it all comes down to doing the math.
We cannot give you the ‘best’ answer as we are not a solar company. It is very dependable of your budget, your intentions, your situation, the fees of your energy company, and so on. The needed calculations to see what might be most profitable for you are very specific. Therefore, for solar power advise we strongly refer to your local specialized solar-energy company.
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