Author Topic: solar charger at work?  (Read 1009 times)

madmaxatx

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solar charger at work?
« on: September 11, 2015, 02:07:27 PM »
Hi all,

I'm trying to figure out if it would work to set up a solar panel at work to charge my Enertia. This is central Texas so there's plenty of sun.

My question is, how much wattage do you need out of a solar panel to effectively charge the bike?

I know the wattage from a home 110v outlet can be as high as 1400 watts on a 15-20 amp breaker.

Would the bike charge effectively on a 300 watt solar panel?

Thanks,

MM

Brammofan

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Re: solar charger at work?
« Reply #1 on: September 11, 2015, 02:10:22 PM »
I'm hoping that someone else will drop in and provide some numbers for you, but I will mention that, according to my kill-a-watt device that plugs into the wall (and, into which I plug my Enertia), it pulls over 900 watts during the high charge portion of charging. Not sure how big a panel(s) you'd need to provide that, but something tells me it's pretty big.
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frodus

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Re: solar charger at work?
« Reply #2 on: September 11, 2015, 02:25:45 PM »
With the Empulse, this would be possible, because part of the EVSE side of it is that the EVSE can tell the charger its max input amps. I built an OpenEVSE that can go down to 1A input, at 120VAC. Tested it and it worked just fine.

I don't know how the Enertia charges, but I don't think its an EVSE input, its just a standard 15A cord, correct?

littlefreak3000

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Re: solar charger at work?
« Reply #3 on: September 11, 2015, 02:40:20 PM »
Wattage is just a link between V and Amps (W = V * A). The bike charges at 120V. So at perfect conditions the you can get a max of 2.5A out of system at 120V. Now solar panels are never perfect plus in order to get it out output 120V you would need a rectifier and a DC to AC converter since that's what the charger expects. Each of these ad additional loses. So maybe out of the whole system on a sunny day you will get 60-70% efficiency so 210 watts (this might be a very forgiving estimate you will probably get less). So maybe you could get 1.75A at 120V which isn't gonna charge the bike very quick if the charger allows it. Plus its a lot more equipment then just attaching a panel to the bike. Plus EV chargers don't really like fluxing power very much so a cloud could wreck your whole day. So maybe even battery storage would be needed to give your bike a constant flow of 120V. So while it would possible to make a little shed at home with a 300w panel or 2 on top and charge your bike it wouldn't be a portable system you could bring to work with out of the box parts.

 I wouldn't mind seeing an EV charger built with this in mind and could handle the irregularity of solar panels to get as much energy that can be spared throughout the day into your bike to give you a few extra % while parked but a solution like that doesn't exists at the moment.

That's my knowledge of the subject like to hear what others thinks.

madmaxatx

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Re: solar charger at work?
« Reply #4 on: September 11, 2015, 02:48:05 PM »
Thanks for the replies, all.

To clarify, I'd be installing the kit at work, not carrying it around with me.

This is type of the solar kit I'm looking at: http://www.homedepot.com/p/Coleman-300-Watt-Solar-Back-Up-Power-Kit-38528/204233141

It says it's 300 w, 12 v, 8.4 amps, but it looks like the inverter has standard "wall type" outlets on it, which is why I was wondering if it might work. Would probably have to get an inverter to output 110v.

Or, this looks like a better option, actually. 110v at 1500 amps: http://www.homedepot.com/p/Wagan-Tech-Solar-E-Power-Panel-Cube-2546/203206445


« Last Edit: September 11, 2015, 02:55:28 PM by madmaxatx »

littlefreak3000

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Re: solar charger at work?
« Reply #5 on: September 11, 2015, 03:05:16 PM »
O then in that case colmen 12V system is gonna lower you to maximum of 100W. So at 120V you can only get .84A out of that inverter, not counting loss. So that system there doesn't seem like enough to charge the bike. Plus if it did work you would probably only get like 800Wh on the battery at most during your work day. The Enertia has a 3.1kWh battery so that means you will get about 25% SoC at the very most.

I can tell you straight up tho if you plug the charger the came with the bike into that system the fuse in the inverter will immediately pop. The charger asks for a lot of amps from the system and there isn't a lot available in this system. That system would be good to run maybe a TV and a few lights. But not something like charging a EV. Charging EVs is on the scale of running a dryer or a microwave.

littlefreak3000

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Re: solar charger at work?
« Reply #6 on: September 11, 2015, 03:10:17 PM »
http://www.homedepot.com/p/Grape-Solar-400-Watt-Off-Grid-Solar-Panel-Kit-GS-400-KIT/203505963

The kits that homedepot call "Off the grid" seem better suited for what you want as it doesn't use that coleman camping 12V inverter in the middle (which is silly). Still no specs on what the output is expected at 120V which is a shame because that's really needed to gauge the system. My guess is it fluctuates a lot depending on the sun conditions. Honestly any solution for this might require batteries which greatly increases the cost.

protomech

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Re: solar charger at work?
« Reply #7 on: September 11, 2015, 04:29:03 PM »
Charging the bike with solar mid-day is always an attractive idea! It may be more difficult than you think to perform, however.

Check out these other threads with more discussion:
http://electricmotorcycleforum.com/boards/index.php?topic=2897.msg14290#msg14290
http://electricmotorcycleforum.com/boards/index.php?topic=3323.0

You have a few options for building the system. Will depend on how the onboard charger behaves when the input voltage and available current drop below what it expects, and whether it can accept wide-ranging DC input (see threads above).

1. Large solar array connected to the onboard charger. (Optional: connect via inverter if OBC can accept only AC, or MPPT DC/DC for better efficiency). Disadvantage is that the OBC will likely be upset if the available power drops out of the minimum it requires.
2. Small solar array connected to a battery system connected to the onboard charger. As with the above, you can use an inverter or MPPT DC/DC between. The battery system should be sized such that it can at least tolerate small interruptions in the solar power supply, in case of intermittent shading.
3. Solar system connected to a custom MPPT DC/DC converter with appropriate output to charge the bike battery. This replaces the OBC and connects directly to the battery. Advantage is that this is absolutely the most efficient way to use the solar panels. Disadvantage is that it's going to require some custom power electronics.. seems like this is a good gap to solve! Maybe someone already offers a solution for this..
4. Connect the solar system to the grid (net-metered), and simply plug the bike into the grid as needed. Giving up, yes, but this is likely to be the best use of the solar panels in general; if directly connected to the bike, the solar panels will only charge the bike during the week when the bike is plugged in; never on weekends, never while you're out riding mid day or before/after you get to work, etc.
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littlefreak3000

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Re: solar charger at work?
« Reply #8 on: September 11, 2015, 07:49:04 PM »
He said exactly what I was trying to so much better lol. Anyone know the model of our OBC? I wanna look up the specs and see what can be done with it. Might already allow for DC.

madmaxatx

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Re: solar charger at work?
« Reply #9 on: May 16, 2016, 09:59:00 AM »
I finally got a kill-a-watt and measured my 2009 Enertia while it was charging.

Starting charge: %10
 Amps: 8
 Volts: 116
 Watts: 945
 total KWh: 3.21