Solar charging - what size/type inverter, etc?

[FiddlerJohn]

... For a floating neutral inverter, the resistor trick mentioned in the LEAF forum is the fix. ...

Charging with Direct Current (batteries charged from a solar array):

I was able to modify an EVSE to put adjustable FLOATING 100VDC-250VDC into the i-MiEV. My circuit bypassed the EVSE ground fault but the on-board charger gave an ERROR. The on-board charger probably also has a ground fault circuit that is not referenced in the above circuit. The resistor trick mentioned in the LEAF forum might satisfy the on-board charger grounding requirements. I could test this idea by using a floating AC after the EVSE to watch for the same on-board charger error. If the on-board charger gives an error with floating AC, I can try the LEAF resistor trick on floating AC and then try it on DC.

Charging from PV modules directly (without batteries) is difficult because the EVSE tells the on-board charger how much current to draw. If the PV modules sees a cloud and drops below the agreed current, the on-board charger will drop out.

 

[SirCaptainAhab]

Ok...

So.. after further research & review of more info, and the info you all have provided here.. I have purchased a new Samlex pure sine wave inverter, and a new 20 amp MPPT charge controller. Should have them in a few weeks or less.

The inverter wont be wired just to the solar panel. It will be hooked up to the batteries.

I hope to do my first test as soon as possible. As soon as I do, I'll let you know what happened.

Captain

 

[RobertC]

So.. after further research & review of more info, and the info you all have provided here.. I have purchased a new Samlex pure sine wave inverter, and a new 20 amp MPPT charge controller. Should have them in a few weeks or less.

I have designed and built small off grid solar projects. Your project sounds very interesting and would be of interest to many electric vehicle owners on this forum. I would be happy to review your design if you can provide the following information:
For your solar panel or panels (if you don't have the manufacturer and model number):
Maximum Power P(MAX) in watts.
Maximum Power Voltage V(PMAX) in volts. (Not open-circuit voltage)
Maximum Power Current I(PMAX) in amps.
For your MPPT charge controller:
Manufacturer and model number.
For your Samlex inverter:
Model number.
For your battery or batteries (if you don't have the manufacturer and model number):
Type, i.e. flooded, gel, AGM, lithium, etc.
Nominal voltage rating in volts.
Charge voltage in volts.
Capacity rating in amp-hours.
Maximum charge current in amps.
Maximum discharge current in amps.

 

[JoeS]

SirCaptainAhab - sorry for jumping in late onto this thread. I have successfully used inexpensive non-sine-wave inverters off both 12vdc and 48vdc into both 120vac and 240vac, inserting modified plugs (see the Leaf forum) into the second outlet of each inverter to ensure GFCI compatibility without letting any smoke out. Using EVSEUpgrade.com modified Mitsu (Panasonic) EVSEs I've been able to ensure the i-MiEV's power draw is well below the inverter's published limits. Your solar-powered project is readily doable and the larger your battery bank the "stiffer" will be your inverter power source. It was nice of RobertC to offer to review your design - if you could post your information here we'll all benefit. All the best.

 

[RobertC]

I have successfully used inexpensive non-sine-wave inverters off both 12vdc and 48vdc into both 120vac and 240vac, inserting modified plugs (see the Leaf forum) into the second outlet of each inverter to ensure GFCI compatibility without letting any smoke out. Using EVSEUpgrade.com modified Mitsu (Panasonic) EVSEs I've been able to ensure the i-MiEV's power draw is well below the inverter's published limits.

Sounds interesting. I am a member of the Leaf forum and I looked and could not find anything. Could you give more details. What non-sine-wave inverters did you use? How was the plug modified? What minimum power draw were you able to get using the EVSEUpgrade?

 

[JoeS]

I have successfully used inexpensive non-sine-wave inverters off both 12vdc and 48vdc into both 120vac and 240vac, inserting modified plugs (see the Leaf forum) into the second outlet of each inverter to ensure GFCI compatibility without letting any smoke out. Using EVSEUpgrade.com modified Mitsu (Panasonic) EVSEs I've been able to ensure the i-MiEV's power draw is well below the inverter's published limits.

Sounds interesting. I am a member of the Leaf forum and I looked and could not find anything. Could you give more details. What non-sine-wave inverters did you use? How was the plug modified? What minimum power draw were you able to get using the EVSEUpgrade?

Over the years we've had some discussions on this very topic. Here's a link which references the exact plug mod procedure identified on the Leaf forum:

http://myimiev.com/forum/viewtopic.php?p=1446#p1446

This same technique worked on my single-ended 48vdc (non-US) 240vac inverter.

I wonder if perhaps some of those posts have been removed for liability reasons, as the usual cautions apply: don't mess with this stuff unless you know what you're doing as it can kill you, and with unknown sneak circuit paths it's always possible to fry something. I once blew up a very nice inverter on the boat by modifying the wiring to comply with legislated boat grounding requirements (the I/O was not isolated).

Yes, finding things on that Leaf forum can be tedious, and I'm happy we're still small enough and organized enough to keep things in their place.

EVSEUpgrade is really nice as it can be easily and quickly programmed to tell the car to draw 6A-12A at 120vac or 6A-13A at 240vac in 1A increments - an ingenious and elegant implementation IMO.

I'd have to look back for the eBay purchase orders for the inverters - they are 2500W stackable: I have separate 120vac and 240vac and 12vdc and 48vdc inputs (but I let the smoke out of one of the 240vac units… don't ask). A number of other smaller cheap inverters also work. It's important that your battery pack be stiff enough to avoid input voltage sag to keep the inverter's protection circuitry from kicking in.

 

[RobertC]

Over the years we've had some discussions on this very topic. Here's a link which references the exact plug mod procedure identified on the Leaf forum:http://myimiev.com/forum/viewtopic.php?p=1446#p1446

I see. The resistors provide continuity between the hot, neutral and ground, but very little current will flow with such a high (100k ohm) resistor.

Yes, finding things on that Leaf forum can be tedious, and I'm happy we're still small enough and organized enough to keep things in their place.

The search tool on these forums leaves a lot to be desired. I have a hard time finding my own old posts.

EVSEUpgrade is really nice as it can be easily and quickly programmed to tell the car to draw 6A-12A at 120vac or 6A-13A at 240vac in 1A increments - an ingenious and elegant implementation IMO.

So at 6A and 120Vac, the inverter and battery must be capable of delivering 720VA or 720 watts. A 48Vdc battery would need to be able to discharge 15 amps continuously (720VA/48V) plus the losses in the inverter. A 12Vdc battery would need to be able to discharge 60 amps continuously (720VA/12V) plus the losses in the inverter.

I have separate 120vac and 240vac and 12vdc and 48vdc inputs (but I let the smoke out of one of the 240vac units… don't ask).

I have accidentally hooked up 120Vac to the low voltage dc terminals of components. They don't last long.

 

[SirCaptainAhab]

Update:

Ok, I just ordered and received this inverter: SAMLEX SSW-350-12A 350 WATT 12VDC INPUT 115VAC OUTPUT PURE SINE WAVE INVERTER. Because I had been informed it was hot wired 120 to one plug and not split.

Just plugging the EVSE in to the wall, as I mentioned before, the car would charge at no more than 9 watts and .26 amps, with no problem.

I got home last night, moved all my batteries to the living room (to be closer to the car with no extension cords), rewired everything to get 12 volts, and hooked up the new inverter. When I plugged in the EVSE charge cord, the orange "charging" light came on! I was ecstatic!! However, my elation was quickly stifled after just 2 seconds. The amps started to ramp up as it got ready to charge, it flickered once, and the fault light came on, with the green power light. And it shut down the inverter immediately. Other times, the inverter would stay on, but change from green to red light, and the EVSE would shut off completely - no lights at all.

The amperage never got above 1.6, before it would shut off. So....I'm not sure what to do next. I think the inverter type is the problem...or the size of it. Not sure.

I'm working on finding an undergrad Elec Eng major at my university to help me work on it.

Captain

 

[JoeS]

Update: Ok, I just ordered and received this inverter: SAMLEX SSW-350-12A 350 WATT 12VDC INPUT 115VAC OUTPUT PURE SINE WAVE INVERTER.

Hello, SirCaptainAhab, what in the world made you think that a 350W output inverter would work? The Mitsu EVSE draws 8A at 120v, which means almost 1000W; thus, you would need a 1500W inverter to give a usable margin. Even the EVSEUpgraded lowest setting of 6A (6*120=720W) would need a 1000W inverter. The inverters I used were 2000W and 2500W and 4000W units. You are simply overloading your poor new baby. I think the Samlex part number is quite misleading by including "12A" as part of their part number, as "12A" has no relationship to the inverter's specifications (either input or output current). This inverter might be useful for running a small TV, but not for feeding our i-MiEV.

 

[SirCaptainAhab]

Ok, scratch the 350watt Samlex inverter. Didn't work. Duh.

Now waiting on the arrival of a new 2000 watt Xantrax ProWatt.

Do I still want to create/use a modified NEMA 5-15P plug with the 2 1/2 watt 100k ohm resistors, that I would plug into the 2nd receptacle of this new inverter, the same way they did on the Generators, as described on: http://www.mynissanleaf.com/viewtopic.php?f=26&t=5792&start=38 ??

Captain

 

[PV1]

You don't need the resistor plug if the car can charge from the inverter. Test your new inverter by plugging the car into it before thinking about making a resistor plug.

That 350 watt inverter would be handy for powering equipment from the i-MiEV, so there's still value to having it.

 

[SirCaptainAhab]

Based just on proximity tonight after work, i just so happen to be right next to a Lowes and Radio Shack. Got the yellow hinged plug NEMA 5-15P for $4.75, and a 4 pack of the 1/2 watt 100 kohms resistors for $1.49!

The new inverter has shipped & will arrive in a couple days. Will try it first of course without the extra mod-plug & see if that works. If not, then with it in the 2nd receptacle of the inverter.

Stay tuned!

Captain

 

[SirCaptainAhab]

That 350 watt inverter would be handy for powering equipment from the i-MiEV, so there's still value to having it.

What do you mean? Please explain.

Thanks,
Captain

 

[PV1]

If you have a power outage or just out away from grid power, you can hook a power inverter to the 12 volt battery in the i-MiEV to run 120 volt equipment. For example, I used my Black and Decker 750 watt inverter to charge electric bicycles from the i-MiEV at an event last summer. The only thing is you must have the car in READY or you'll run the 12 volt battery flat and have to visit the dealer to have a warning light reset.

Your 350 watt inverter takes 12 volts input, correct?

 

[SirCaptainAhab]

Yes, it is. Ah ok, now I understand. Just as with any type of cigarette lighter plug in connected to the inverter. So the car has to be "on/ready" just like a regular vehicle, or you run the little battery down.

Got it! Thanks.

Captain

 

[SirCaptainAhab]

Ok...update:

Received my new Xantrex 2000 watt ProWatt Inverter today. Have attempted to charge the car again. It acts like it wants to, and starts to charge, but then faults and the built-in GCFI outlet trips each time. So I'm going to attempt to wire up the 2nd plug in as describe above, and try again.

Captain

 

[RobertC]

Received my new Xantrex 2000 watt ProWatt Inverter today. Have attempted to charge the car again. It acts like it wants to, and starts to charge, but then faults and the built-in GCFI outlet trips each time. So I'm going to attempt to wire up the 2nd plug in as describe above, and try again.

I have a used forklift battery that is charged via solar cells.
In order not to overload the battery, I will Charge my iMiEv with only about 500W.
How can I do it?

A common misconception about off-grid solar PV systems is that the electrical load can be connected to solar panels. The electrical load is connected to batteries, and the batteries are charged by solar panels. The batteries, not the solar panels, must be capable of supplying the electrical load continuously.

 

[Aerowhatt]

RobertC there is some wiggle room here though.

For instance on a mostly clear sunny day I can run much larger loads on my off grid backup system than I would try to at night. In fact one could charge from solar panels "directly" with a small high rate AGM battery acting as a buffer.

It"s far more efficient to run high loads on it during the day when possible. Most (or all) of the power is going straight from the charge controller to the inverter bypassing the charging and discharging losses associated with the battery.

For example I have an electric clothes dryer modified to run on 120v instead of 240v (a simple internal rewire) It pulls just under 2000 watts continuously and dries wet towels or anything in 65 minutes or less. That works out to a 170 amp load on a 12 volt system. I use a 2000 watt inverter for it and in full sun only need one 104 AH high rate AGM battery in the mix to make it work. With 5 hours of prime sun in a day I can easily run three loads and have a 95% battery SOC going into the evening.

Now take that same scenario with just the battery at night and about 15 to 18 minutes into the first drying cycle the inverter would (low battery shut down).

 

[RobertC]

For example I have an electric clothes dryer modified to run on 120v instead of 240v (a simple internal rewire) It pulls just under 2000 watts continuously and dries wet towels or anything in 65 minutes or less. That works out to a 170 amp load on a 12 volt system. I use a 2000 watt inverter for it and in full sun only need one 104 AH high rate AGM battery in the mix to make it work. With 5 hours of prime sun in a day I can easily run three loads and have a 95% battery SOC going into the evening.

Your off-grid system would work well with a Level 1 EVSE to charge an electric vehicle during a sunny day. What wattage solar panels are you using? What charge controller do you use?

 

[Aerowhatt]

Your off-grid system would work well with a Level 1 EVSE to charge an electric vehicle during a sunny day. What wattage solar panels are you using? What charge controller do you use?

I hope so. I've used it to power lower wattage chargers on smaller EV's (motorcycle for instance). The example I used is emergency usage that I have tested. In regular use I have a larger bank of mismatched used EV (no longer suitable capacity for mobile applications) AGM lead acid batteries. Any mainstream off grid solar designer would say it won't work. But I have 4 years of hard data showing that it does work and work well. Essentially my battery bank is free and will continue to be, as long as I do EV service and modifications. Some of them are orbitals that were manufactured in 2004!

The panels are 60 cell SolarWorld panels for a total of 2600 watts, The charge controllers are Morningstar 65 amp MPPT units (three paralleled). In day to day practice the panels are grid tied, but are also wired to divert the DC to the charge controllers if the grid is down. A small investment IMO to keep the food cold and our kesters warm or cool (depending on season) during a prolonged outage. Why only a 12 volt battery bank when 48V would be more efficient? It's much easier to use mismatched batteries if there are no series strings. Also a charged iMiEV battery could keep the critical loads going for up to 4 days through the DC to DC converter in the car (12 volt output). A Gasser can idle at about .6 gallons per hour cranking out 45 to 80 amps of charging power (again 12 volt output). So for the sake of flexibility of power sources 12 volts made the most sense to me.

Aerowhatt