Solar Charging

[Westfork]

I am all for a BEV. Home is off grid. Do not have enough reserve power to charge an EV when the outside air temps are over 100. Would like to set up a separate system. Can’t seem to wrap my head around it. Want the system as simple as possible (cheap). Ideally Solar panels and a charge controller direct to the battery. This works with low voltage DC. But dealing with a system that I know nothing about. Want to charge battery only when the solar panels are producing power. Do not want to add a battery to the system. Figure the an inverter will be required. Not sure how that will work with out a battery. Anybody charging their EV battery direct from a stand alone solar array? Since the EV battery might not get charged in one day, How would this affect the EV battery cycle count.

 

[cyure]

I am all for a BEV. Home is off grid. Do not have enough power reserve power to charge an EV when the outside air temps are over 100. Would like to set up a separate system. Can’t seem to wrap my head around it. Want the system as simple as possible (cheap). Ideally Solar panels and a charge controller direct to the battery. This works with low voltage DC. But dealing with a system that I know nothing about. Want to charge battery only when the solar panels are producing power. Do not want to add a battery to the system. Figure the an inverter will be required. Not sure how that will work with out a battery. Anybody charging their EV battery direct from a stand alone solar array? Since the EV battery might not get charged in one day, How would this affect the EV battery cycle count.

tap tap…@SpaceEVDriver will you please come on down….

 

[SpaceEVDriver]

I am all for a BEV. Home is off grid. Do not have enough reserve power to charge an EV when the outside air temps are over 100. Would like to set up a separate system. Can’t seem to wrap my head around it. Want the system as simple as possible (cheap). Ideally Solar panels and a charge controller direct to the battery. This works with low voltage DC. But dealing with a system that I know nothing about. Want to charge battery only when the solar panels are producing power. Do not want to add a battery to the system. Figure the an inverter will be required. Not sure how that will work with out a battery. Anybody charging their EV battery direct from a stand alone solar array? Since the EV battery might not get charged in one day, How would this affect the EV battery cycle count.

We need more information.

• Does your home run on DC or do you already have an inverter?
  • What kind of inverter do you have?
  • 120 Volt single phase?
  • 240 Volt, split phase?
  • Something else?
• What’s the voltage of your PV system
  • 12 Volts?
  • 24 Volts?
  • 48 Volts?
  • Higher?
• Do you want to buy more PV panels?
  • How much (watts) are you willing to get?
  • Would it be a separate system from the home system?
  • Would you be willing to do a higher-voltage system?
• What’s the investment level you are able to commit to?
• Is this DIY or are you going to have someone else engineer and install it?

Lithium battery cycle counts are based on a full charge-discharge-charge cycle. So 0% to 100% to 0%. So, for example, if you use 20% every day and recharge back to the starting level, then you get one cycle in five days.

At this time, we only charge our truck via standalone PV when we’re boondock camping. We have a 5 kWh power station that we put in the bed of the truck. We charge the power station with the PV and the power station provides the voltage/power conditioning for the EVSE and some extra storage that we dump into the truck when the sun isn’t shining. But it’s a 120 Volt single phase, so can only charge at 1.2 kW rate, which is relatively slow and in our neck of the country, we end up wasting potential power. I have the fixings for larger system, but don’t have the time to build it all out until late winter.

 

[J Alynn]

tap tap…@SpaceEVDriver will you please come on down….

Well I was patiently waiting but guess somebody was anxious to get your free services and education

 

[cyure]

Well I was patiently waiting but guess somebody was anxious to get your free services and education

Hey who ever said I have patience. Waiting for my scout is killing me.

 

[J Alynn]

Hey who ever said I have patience. Waiting for my scout is killing me.

Somebody here keeps saying Faith and patience-somebody must be manifesting

 

[Westfork]

House is AC/DC. 120AC, 48DC. 2-4000 watt inverters. I have 14- 330w panels available. House is now running on 16-420w. Need to be a standalone system. We have 48 volt plugs throughout the house. No 240v as we used 20 amp 240v plugs for the 48v to meet code. Will not do that again. Higher voltage is fine. My house inverters were good for 150 volts. Decreased system voltage so as to not exceed 150 in cold weather. More than likely did not have to do that. I am in an area where DIY is the norm for off grid solar.
I read some of the posts in “similar threads” which was helpful.

Thanks for the help.

 

[SpaceEVDriver]

House is AC/DC. 120AC, 48DC. 2-4000 watt inverters. I have 14- 330w panels available. House is now running on 16-420w. Need to be a standalone system. We have 48 volt plugs throughout the house. No 240v as we used 20 amp 240v plugs for the 48v to meet code. Will not do that again. Higher voltage is fine. My house inverters were good for 150 volts. Decreased system voltage so as to not exceed 150 in cold weather. More than likely did not have to do that. I am in an area where DIY is the norm for off grid solar.
I read some of the posts in “similar threads” which was helpful.

Thanks for the help.

Some more questions that I forgot to ask before:
How many miles do you expect to travel in a normal week?
How much are you concerned about needing to go for a long drive on short notice?


For the sake of this comment, I’ll assume you drive enough that a Level 1 charger won’t do the job for the driving you do. Level 1 would be easier and cheaper to implement, but it’s not as flexible nor as fast nor as efficient.

You have two options for faster charging.

1. AC 240 Volt “Level 2” charging
2. DC “Fast” charging — I’ll leave this out of this comment for various reasons. We can come back to it if needed.

A comment about EV charging and solar power: Most chargers and vehicles really don’t like the fluctuating “dirty” power created by PV. Some kind of method for “smoothing” that power out is likely to be necessary. Otherwise your car or EVSE may give an error if a bit of cloud or whatever causes the power to fluctuate too rapidly. I’m not sure you’ll be able to get away without a battery or power station. I know you said you didn’t want to get another battery, but I’m not sure you can charge an EV from PV without one. I haven’t been able to get any of my L2 EVSEs to directly charge with just PV connected—they’re just too sensitive to noise and other issues.

For Level 2 charging this is what I would do:

• Use at least 4, up to all of the 330 Watt, 48 Volt panels for up to 4620 Watts
  • I would wire these as 4S3P or 7S2P for 192 or 336 volts
  • Wiring as above means you can decrease the amperage coming in from the panels and so you don’t have to have too-large wires
• One or two 48 (51.2) Volt LFP, 100 Ah batteries
  • These can be had for about $400 each or much more if you’re worried about brand
  • This would get you a 10 kWh battery bank
  • You don’t need a lot of storage capacity, you just need a buffer between the solar input and the EVSE
• A 48 Volt, 5000 Watt pure sine wave off-grid MPPT charge controller / inverter with split phase 240 volt output
  • For example, the GroWatt 5k off-grid inverter
  • These can be had for about $800 to $1600 or a lot more if you have concerns about brand
• An adjustable amperage Level 2 EVSE
  • This can be had for about $400 to $1500, depending on the features you want
  • If you get an Emporia Pro charger, you can program it to only use “excess” solar. In your case, all the solar is “excess,” but the charger is able to automatically adjust its amperage to match the available solar power.

This is about a $2k-$3k system.

A Level 1 (1.2 kW charge rate) would be cheaper. But it’s not terribly fast to charge. And its efficiency is not very good.

 

[Westfork]

Some more questions that I forgot to ask before:
How many miles do you expect to travel in a normal week?
How much are you concerned about needing to go for a long drive on short notice?


For the sake of this comment, I’ll assume you drive enough that a Level 1 charger won’t do the job for the driving you do. Level 1 would be easier and cheaper to implement, but it’s not as flexible nor as fast nor as efficient.

You have two options for faster charging.

1. AC 240 Volt “Level 2” charging
2. DC “Fast” charging — I’ll leave this out of this comment for various reasons. We can come back to it if needed.

A comment about EV charging and solar power: Most chargers and vehicles really don’t like the fluctuating “dirty” power created by PV. Some kind of method for “smoothing” that power out is likely to be necessary. Otherwise your car or EVSE may give an error if a bit of cloud or whatever causes the power to fluctuate too rapidly. I’m not sure you’ll be able to get away without a battery or power station. I know you said you didn’t want to get another battery, but I’m not sure you can charge an EV from PV without one. I haven’t been able to get any of my L2 EVSEs to directly charge with just PV connected—they’re just too sensitive to noise and other issues.

For Level 2 charging this is what I would do:

• Use at least 4, up to all of the 330 Watt, 48 Volt panels for up to 4620 Watts
  • I would wire these as 4S3P or 7S2P for 192 or 336 volts
  • Wiring as above means you can decrease the amperage coming in from the panels and so you don’t have to have too-large wires
• One or two 48 (51.2) Volt LFP, 100 Ah batteries
  • These can be had for about $400 each or much more if you’re worried about brand
  • This would get you a 10 kWh battery bank
  • You don’t need a lot of storage capacity, you just need a buffer between the solar input and the EVSE
• A 48 Volt, 5000 Watt pure sine wave off-grid MPPT charge controller / inverter with split phase 240 volt output
  • For example, the GroWatt 5k off-grid inverter
  • These can be had for about $800 to $1600 or a lot more if you have concerns about brand
• An adjustable amperage Level 2 EVSE
  • This can be had for about $400 to $1500, depending on the features you want
  • If you get an Emporia Pro charger, you can program it to only use “excess” solar. In your case, all the solar is “excess,” but the charger is able to automatically adjust its amperage to match the available solar power.

This is about a $2k-$3k system.

A Level 1 (1.2 kW charge rate) would be cheaper. But it’s not terribly fast to charge. And its efficiency is not very good.

Averaging 300 miles/week. Not too concerned about long trips. Usually planned in advance.
Inverters have improved in the last ten years. And the prices have come down.
May look into the Emporia Pro Charger for the house. If the 240 circuit is just for charging outside may be ok. Hot summers would be the only concern, for now.
Thanks for the help. It helped clear the cobwebs. Now might be able to get my head wrapped around it.

 

[maynard]

Well I was patiently waiting but guess somebody was anxious to get your free services and education

Heck - we all are! I love the education I get here! THANK YOU!!!!

 

[SpaceEVDriver]

Averaging 300 miles/week. Not too concerned about long trips. Usually planned in advance.
Inverters have improved in the last ten years. And the prices have come down.
May look into the Emporia Pro Charger for the house. If the 240 circuit is just for charging outside may be ok. Hot summers would be the only concern, for now.
Thanks for the help. It helped clear the cobwebs. Now might be able to get my head wrapped around it.

I have only once had a heat-related home charger issue. My workshop is uninsulated, has a black roof, and gets up to 120 F in the summer when it's 90 F outside. I was running the 80 Amp charger at 100% charge rate with the doors closed. I live at 7000 feet elevation, which is above the 2000 meters most electronics specs sheets identify as the maximum safe altitude for operation (due to poor cooling efficiency).

 

[SpaceEVDriver]

Averaging 300 miles/week. Not too concerned about long trips. Usually planned in advance.
Inverters have improved in the last ten years. And the prices have come down.
May look into the Emporia Pro Charger for the house. If the 240 circuit is just for charging outside may be ok. Hot summers would be the only concern, for now.
Thanks for the help. It helped clear the cobwebs. Now might be able to get my head wrapped around it.

One thing I forgot to mention is that I would add a method (mechanical or automatic) for transferring power to the house system from the EV system when the EV is fully charged so you’re not “wasting” the production.