Bare Minimum to charge an EV

[dre]

I'm looking to set up a simple solar charging station at work, but I don't need a full on system, backup batteries, grid-tie or anything like that. Just hey if it's sunny out I can charge my car, 220 would be great but 110 will work. Just want Solar panels, whatever in between and then an outlet, but to include whatever circuit protection is also needed. I know Will has mentioned has rig charging his Tesla, but that will come later.

 

[FilterGuy]

What wattage do you want? An EV has a huge battery bank so to do any significant charging will require a decent sized array of solar panels.

 

[dre]

Whatever I can get, I know I'm going to need at least 5 panels to make any sort of dent in the charging. But my car is a PHEV not a full on EV so the battery is smaller, just thinking 6 large panels wired in series to whatever I need.

 

[FilterGuy]

An interesting challenge. Most charge controllers and Inverters want a battery as a kind of voltage buffer and don't work well without it.
In a separate thread we are discussing the ElectroDaucus SolarBMS. The reason I bring that up is the electrodaucus literature says your 'battery bank' could be capacitors. So maybe something like this would work:

 

[tictag]

Some (most?) EVs can be charged from either AC or DC. DC charging would avoid inverter losses but, depending on your battery, you'll likely need quite a high voltage. Tesla's need around 400V. There's also a 'protocol' challenge in making the EV happy there's a properly spec'd DC charger attached. I've heard this is via CANBUS, but others say it's just a set of resisters on the right pins.

In theory you could connect a PV array directly to an inverter but this is fraught with problems, not least the efficiency (the inverter on load will drag the PV voltage down i.e. outside of it's maximum power point). Most people do use a battery as it 'buffers' the PV output but if you think about grid-tie inverters, they take the DC from a PV array and invert it directly for feeding the grid, so it is definitely possible.

 

[tictag]

Ahhh, @FilterGuy replied as I was writing! I'm not familiar with the ElectroDaucus.

 

[John Frum]

I'm looking to set up a simple solar charging station at work, but I don't need a full on system, backup batteries, grid-tie or anything like that. Just hey if it's sunny out I can charge my car, 220 would be great but 110 will work. Just want Solar panels, whatever in between and then an outlet, but to include whatever circuit protection is also needed. I know Will has mentioned has rig charging his Tesla, but that will come later.

The simplest solution is to charge your vehicle from grid power.

 

[tictag]

The simplest solution is to charge your vehicle from grid power.

Booooorrrrring!

 

[dre]

Booooorrrrring!

Thank you!

 

[dre]

Some (most?) EVs can be charged from either AC or DC. DC charging would avoid inverter losses but, depending on your battery, you'll likely need quite a high voltage. Tesla's need around 400V. There's also a 'protocol' challenge in making the EV happy there's a properly spec'd DC charger attached. I've heard this is via CANBUS, but others say it's just a set of resisters on the right pins.

In theory you could connect a PV array directly to an inverter but this is fraught with problems, not least the efficiency (the inverter on load will drag the PV voltage down i.e. outside of it's maximum point). Most people do use a battery as it 'buffers' the PV output but if you think about grid-tie inverters, they take the DC from a PV array and invert it directly for feeding the grid, so it is definitely possible.

Mine can accept DC to DC fast charging, you are correct at around 400V, but to get a set up to work via solar would require more surface area than I have available. I am hoping to get 220V at low amps, 8-13A.

 

[tictag]

A grid-tie inverter might well fit the bill but most are designed to require a grid supply before they will function (and switches off if it disconnected). I dare say there are products out there that do not have this behaviour. For example, there are 'portable power' products out there that basically consist of a foldable PV panel with a 'micro inverter' on the back - the panel itself outputs mains power. I understand that these can also be paralleled up (i.e. the inverters all sync up) to provide a reasonable supply capacity. Might be an option.

 

[dre]

I was thinking a grid-tie might be the easiest, it should have the builtin protection that if there's not enough going in then output would stop to charger.

 

[FilterGuy]

@dre, the grid tie inverters will have to be hooked to the grid to work. To stay in code, there are a lot of requirements on the installation.... and technically you have to get permits from both the utility company and your local municipality.

Also, you will be charging regardless of whether your panels are providing power. That may be a good thing or a bad thing.

 

[Dzl]

Ahhh, @FilterGuy replied as I was writing! I'm not familiar with the ElectroDaucus.

Here is the thread FilterGuy was referring to. Dacian comes up with some pretty innovative products and creative ideas. He designed his house to be 100% solar powered, including using solar generated electricity to directly heat his home.

One of the unorthodox but well reasoned data based arguments he makes is that spending money on an MPPT controller rarely makes economic sense (if the money can be used towards more PV instead), and that a solar rich/storage lean ratio is optimal in most cases.

 

[tictag]

grid tie inverters will have to be hooked to the grid to work.

That's not strictly accurate, but generally true yes. I mean my inverter is a grid-tie (or rather it can be grid-tied) but it functions just fine without it. In fact, it can sync to a genset and augment the genset power for high demands. I'm not trying to be pedantic, I'm just saying there are 'grid-tie' inverters out there that do not necessarily have to be actually tied to the grid to function.

 

[Supervstech]

The issue with using a grid tie is amps output...
Not many can put out 15amps 240v... that would be over 3000watts... most are around 600watts...
13 Amos at 240v is 3120Watts... that's TEN 300Watt panels.

A rather large array.

If you can charge a battery bank when you arent charging the car, that might work...

 

[Supervstech]

Whatever I can get, I know I'm going to need at least 5 panels to make any sort of dent in the charging. But my car is a PHEV not a full on EV so the battery is smaller, just thinking 6 large panels wired in series to whatever I need.

Define "large panels" 375Watt, panels x6 would be about 2200W with good sun,
That's about 9 amps at 240v, so that would work... those panels are HUGE, though, about 4x8' so, you are talking a huge array at work...

 

[dre]

Define "large panels" 375Watt, panels x6 would be about 2200W with good sun,
That's about 9 amps at 240v, so that would work... those panels are HUGE, though, about 4x8' so, you are talking a huge array at work...

That might actually work, the area I am looking at putting the panels are "permanently" parked trailers being used as rooms attached to the warehouse. My cousin is the owner and has a Tesla, I've run the idea already by him about putting a charging station at work. The face southwest and get a decent amount of sun. Just a fun project idea.