Charging an EV with solar cells

[edwinchester]

Hi, last June we bought a Neta V for the school run which is about 120 kms per day.

We can charge it overnight on the TOU tariff.

I would like the option to be able to charge our car during the day using solar. Garden space is not an issue so I'd like to build a car port with a roof of solar panels.

As a solar novice I'm asking for advice on what will be required, assuming panels, inverter and charger for starters.

If anyone has any pics of a similar setup that would be great.

Thanks for reading Ed.

[Bandersnatch]

I have 2 EVs and as I am completely off-grid, both my cars are charged from Solar.

 

If you charge from the wall box it will draw 7kW of power and if you use the mobile charger it will draw about 3kW.

 

To power the wall charger you would need at least 10kW of PV and a 10kW inverter. If you decide to mobile charger a 5kW system will be sufficient. Remember that your solar system will top up from the grid if solar is not sufficient. 

 

The Neta V comes with V2L so you could use the car to power the house at night.

 

I have many videos on that on my channel. 

 

 

 

 

 

 

[KhunLA]

This thread should be enlightening ... link

[jvs]

6 minutes ago, Bandersnatch said:

I have 2 EVs and as I am completely off-grid, both my cars are charged from Solar.

 

If you charge from the wall box it will draw 7kW of power and if you use the mobile charger it will draw about 3kW.

 

To power the wall charger you would need at least 10kW of PV and a 10kW inverter. If you decide to mobile charger a 5kW system will be sufficient. Remember that your solar system will top up from the grid if solar is not sufficient. 

 

The Neta V comes with V2L so you could use the car to power the house at night.

 

I have many videos on that on my channel. 

 

 

 

 

 

 

Very interesting,is it also possible to charge the car using DC,so without a converter?

 

[KhunLA]

29 minutes ago, jvs said:

Very interesting, is it also possible to charge the car using DC, so without a converter?

 

Not sure I understand the question.  If meaning directly off the solar panels, I haven't a clue or techie enough.  Maybe if having proper cables and such, but wouldn't recommend it.

 

This is what our MG ZS will accept 1 phase & DC @ CS.  Most fast CS supply at least 50kWh, up to 125 or even 175kWh, I think.  Although the ZS will only accept up to 76kWh.

 

Assume the Neta V is in the same range, with their granny/emergency cable, wall cable, and acceptance from DC CSs. 

 

Edited February 24 by KhunLA

[jvs]

2 minutes ago, KhunLA said:

Not sure I understand the question.  If meaning directly off the solar panels, I haven't a clue or techie enough.  Maybe if having proper cables and such, but wouldn't recommend it.

 

This is what our MG ZS will accept 1 phase & DC @ CS.  Most fast CS supply at least 50kWh, up to 125 or even 175kWh, I think.  Although the ZS will only accept up to 76kWh.

 

Assume the Neta V is in the same range, with their granny/emergency cable, wall cable, and acceptance from DC CSs. 

 

I mean straight from the solar power cells into the battery.Fast chargers are DC anyway so why can you not just have a few solar panels feeding the right voltage straight into the car?

Bypassing a few steps that are not really necessary?

I am using a DC pump straight of my panels and that system runs really well without any controlers or chargers.

 

 

[KhunLA]

20 minutes ago, jvs said:

I mean straight from the solar power cells into the battery.Fast chargers are DC anyway so why can you not just have a few solar panels feeding the right voltage straight into the car?

Bypassing a few steps that are not really necessary?

I am using a DC pump straight of my panels and that system runs really well without any controlers or chargers.

Guess it would be possible, and if we had the proper cable and bypassed our inverter/breaker box, then our panels put out 9.7kWh (barring any loss), although that's 18 pv X 540w.   So a bit faster than the wall charger, and much faster than granny charger. 

 

Although not exactly an inexpensive option, (~฿100k +/-) but faster.  Although without the inverter, would limit it's use. 

Edited February 24 by KhunLA

[Bandersnatch]

It is definitely possible, but the efficiency gained would most likely be outweighed by the extra cost of the equipment.

 

EVs in Thailand usually come with a free wall charger and installation. My 7kW AC charger results in 6.7kW DC going into my car.

 

 

https://www.ampernext.com/products/first-30kw-dc-dc-solar-ev-charger/

[lom]

1 hour ago, jvs said:

I mean straight from the solar power cells into the battery.Fast chargers are DC anyway so why can you not just have a few solar panels feeding the right voltage straight into the car?

Fast chargers are able to detect the cars DC battery voltage (200 - 800V) and adjust itself to match that voltage.

In theory you could set up a solar panel array matching your cars DC voltage but I think you would at least have an MPPT in between in

order to get most out of your panels.

 

There is a reason why V2L/V2G/V2H/V2V is AC, it can be connected directly to the consumers regardless of what DC voltage the car battery has.

The inverter in the car is 2-ways, converts incoming AC to DC when charging the car and converts DC to AC when delivering to an external load.

Since the inverter is made for the car then it is made for the specific DC battery voltage of the car.

 

Correction: Rapid charger  (Level 3) is the direct DC charger that can adjust itself to the car batt voltage.

 

Edited February 24 by lom
Correction

[edwinchester]

4 hours ago, KhunLA said:

This thread should be enlightening ... link

Haha I found that topic about 5 minutes after I posted mine. Yes it's useful thanks.

[edwinchester]

5 hours ago, Bandersnatch said:

I have 2 EVs and as I am completely off-grid, both my cars are charged from Solar.

 

If you charge from the wall box it will draw 7kW of power and if you use the mobile charger it will draw about 3kW.

 

To power the wall charger you would need at least 10kW of PV and a 10kW inverter. If you decide to mobile charger a 5kW system will be sufficient. Remember that your solar system will top up from the grid if solar is not sufficient. 

 

The Neta V comes with V2L so you could use the car to power the house at night.

 

I have many videos on that on my channel. 

 

 

 

 

 

 

Thanks for the reply and very envious of your setup. Really like your vids, have been binge watching waiting for daughter at school today.

[Crossy]

All good stuff above.

 

The problem with charging directly from solar is that solar isn't constant. That coupled with EV chargers being fixed rate (or at least not remotely controllable) makes life a bit difficult.

 

By far the easiest / cheapest way to do this is to go grid-tie with an inverter that has a current-transformer so it can be set to not export to the grid (with an electronic meter you really don't want to export).

 

A 5kW grid-tie inverter with about 6kW of panels will easily power your granny-lead during the day and any excess generated will go to offset your daytime domestic usage (which also applies whilst you're out and about in the EV).

 

There are solutions that provide a variable charge rate EVSE (Electric Vehicle Supply Equipment) but off the shelf units are expensive and not everyone wants to start playing with something like Open-EVSE.

 

 

[edwinchester]

3 hours ago, Crossy said:

All good stuff above.

 

The problem with charging directly from solar is that solar isn't constant. That coupled with EV chargers being fixed rate (or at least not remotely controllable) makes life a bit difficult.

 

By far the easiest / cheapest way to do this is to go grid-tie with an inverter that has a current-transformer so it can be set to not export to the grid (with an electronic meter you really don't want to export).

 

A 5kW grid-tie inverter with about 6kW of panels will easily power your granny-lead during the day and any excess generated will go to offset your daytime domestic usage (which also applies whilst you're out and about in the EV).

 

There are solutions that provide a variable charge rate EVSE (Electric Vehicle Supply Equipment) but off the shelf units are expensive and not everyone wants to start playing with something like Open-EVSE.

 

 

Hi thanks for your comment.

The ideal place, for sunlight, for our proposed solar carport is about 40-50 metres from a connection into our house. Is this too far for a grid-tie inverter or not a problem? Please excuse my ignorance.

[Crossy]

13 hours ago, edwinchester said:

Hi thanks for your comment.

The ideal place, for sunlight, for our proposed solar carport is about 40-50 metres from a connection into our house. Is this too far for a grid-tie inverter or not a problem? Please excuse my ignorance.

 

Nah that will work just fine with correctly sized cable.

[edwinchester]

Just now, Crossy said:

 

Nah that will work just fine with correctly sized cable.

Thanks for the reply. Really appreciate your input on electrical topics.

[Crossy]

Would you put the EVSE (car charger) near the panels or near the house?

 

[edwinchester]

13 minutes ago, Crossy said:

Would you put the EVSE (car charger) near the panels or near the house?

 

I would like the charger in the carport.

My thinking was to have the inverter in the carport, under the panels, so I can use the portable granny charger.

Edited February 25 by edwinchester

[Crossy]

3 minutes ago, edwinchester said:

I would like the charger to be placed in the carport, under the panels.

 

Fine, your required wiring would be determined by the inverter you intend using.

 

[edwinchester]

As a follow up....asked a local sparky and he recommended this inverter. He doesn't have a financial interest as he suggested I buy myself.

 

Anyone know if this is any good or not worth the money?

Thanks for reading.

[KhunLA]

1 hour ago, edwinchester said:

As a follow up....asked a local sparky and he recommended this inverter. He doesn't have a financial interest as he suggested I buy myself.

 

Anyone know if this is any good or not worth the money?

Thanks for reading.

Unfamiliar with the brand, but if going that route, then I'd go with 48v, in case wanting to add a battery pack to the system later.   6.2kWh should suffice, for granny charger, plus running something else off it, when producing extra, if wanting.  

 

Carport will need to support, panels & bits, (about 400kg) in addition to roofing.  Twelve 540w panels would power it, needing about 40m² of roof, as most panels are about 2.6m² each (X 12 = 36m²) 

 

We used 540w;

Edited March 4 by KhunLA

[lom]

3 hours ago, edwinchester said:

Anyone know if this is any good or not worth the money?

It is an ok inverter for the money, it is a cheap inverter from a known company.

The price diff between the 4.2KW/24V and the 6.2KW/48V is so small that you should buy the 6.2KW version.

 

Edit: The inverter can not export power to the grid.

Edited March 4 by lom

[edwinchester]

3 hours ago, KhunLA said:

Unfamiliar with the brand, but if going that route, then I'd go with 48v, in case wanting to add a battery pack to the system later.   6.2kWh should suffice, for granny charger, plus running something else off it, when producing extra, if wanting.  

 

Carport will need to support, panels & bits, (about 400kg) in addition to roofing.  Twelve 540w panels would power it, needing about 40m² of roof, as most panels are about 2.6m² each (X 12 = 36m²) 

 

We used 540w;

Hi, thanks for the reply. How about the panels being the roof or is that a bad idea? I was thinking of just the posts with steel framework on which to attach the panels. Minor leaks between the panels don't worry me and they should be cooler with no roof tiles close below them.

Edited March 4 by edwinchester

[edwinchester]

1 hour ago, lom said:

It is an ok inverter for the money, it is a cheap inverter from a known company.

The price diff between the 4.2KW/24V and the 6.2KW/48V is so small that you should buy the 6.2KW version.

 

Edit: The inverter can not export power to the grid.

Hi thanks for your reply. Exporting back to the grid is not a priority considering how low the rate is and how strict PEA is on the equipment used.