Solar Charger Built For E-bikes

I posted this 500 and some pages into the Stealth Bomber thread which means it's effectively be buried. Figured I'd post in the ALT Energy section as it may benefit other solar noobs like myself.

Decided to test my hand at building an off the grid solar setup for the garage to charge a pair of Stromers, a Juiced Rider and a Stealth Bomber.

Once I put a watt meter on the Bomber's charger and found it draws about 580-600 watts I knew I needed to have a decently capable solar system.

Found some nice 12v batts (102 lbs each !!) on Craigslist , picked up some cables from the auto parts store and of course 200 watts Renogy Panels off of Amazon.

A 1000watt inverter (i had laying around) and a cheap $20 charge controller, Im thinking about switching to 24v by running 2 banks of series batts and series panels when my MPPT charge controller arrives.

Looks good, but I'd encourage others to just install a small solar grid tie system your home. Now your expensive modules are charging/working ALL the time, not just when you are charging batteries. It breaks my heart to see solar panels not working! That is the true beauty of a grid tie install as compared to a off grid. Off grid, the batteries fill, and the panels just sit there the rest of the day! All that wasted power! Grid tie you get max return on your investment, for decades no less. I guess what I'm saying is if you are going to spend 1 or 2 grand on a little off grid system for charging your bike batteries, maybe consider spending another 1 or 2 and you will be repaid many times over, and still be recharging using solar.

If you re charge when you are turning your meter backwards, you are as "pure" as charging direct. BTW, my last power bill shows I am approaching an 11,000 KW credit with my utility, despite using the air conditioner quite a bit this summer. I like being able, when ever challenged by someone about how electric vehicles just shift the load to coal burning power plants, that mine doesn't! And more fuel is on the way tomorrow! Then I hit the throttle and blast off.

craneplaneguy said:

Looks good, but I'd encourage others to just install a small solar grid tie system your home. Now your expensive modules are charging/working ALL the time, not just when you are charging batteries. It breaks my heart to see solar panels not working! That is the true beauty of a grid tie install as compared to a off grid. Off grid, the batteries fill, and the panels just sit there the rest of the day! All that wasted power! Grid tie you get max return on your investment, for decades no less. I guess what I'm saying is if you are going to spend 1 or 2 grand on a little off grid system for charging your bike batteries, maybe consider spending another 1 or 2 and you will be repaid many times over, and still be recharging using solar.

If you re charge when you are turning your meter backwards, you are as "pure" as charging direct. BTW, my last power bill shows I am approaching an 11,000 KW credit with my utility, despite using the air conditioner quite a bit this summer. I like being able, when ever challenged by someone about how electric vehicles just shift the load to coal burning power plants, that mine doesn't! And more fuel is on the way tomorrow! Then I hit the throttle and blast off.

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Ive got maybe $500-$600 in this setup, theres just no way Im dumping $1.5-$2k just to hook to the grid. Besides, they all spend half thier lifetime doing nothing from about 8pm - 6am every solar panel on earth is not working. I may build the same setup for a Mercedes Benz sprinter van at some point well.

Small scale electricity generation is difficult to make cost efficiently.

However, the satisfaction of riding on power you've arranged to be generated yourself must be deeply satisfying. Cool set up, I might look to do something similar in the near future.

Lurkin said:

Small scale electricity generation is difficult to make cost efficiently.

However, the satisfaction of riding on power you've arranged to be generated yourself must be deeply satisfying. Cool set up, I might look to do something similar in the near future.

Click to expand...

Is it cost effective? Absolutely not, did I learn a ton while doing this? Absolutely.

MPPT charge controllers really seem to increase efficiency as well.

I would like to see the efficiency of your system. Could you monitor the Wh going into the inverter compared to the Wh used to charge the battery? I assume the efficiency is 70% or lower...

Maybe a DC-DC Boost charger is the more interesting option.

Maybe you try the Ming He MPT-7210A instead. It's a quite bad solar MPP charger, but would be ok to charge batteries from 12V or better 24V lead acid batteries.... Efficiency is around 85-90%. Maximum voltage is 90V(?), I don't know if that's enough for your ebikes...

https://www.youtube.com/watch?v=IfHyPNkxlrU

No idea what the efficiency is on this system but it charges all of my bikes, easily. I have added 2 more panels ( 4 total), a much better 24v 2000w Pure Sine wave Inverter an converted my whole battery system to 24v.

If I can work out the grounding fault on my "brick" trickle charger (doesn't like my Cotek Inverter even though it is grounded directly to a brand new 8 foot copper grounding rod), I may also try to trickle charge my Nissan Leaf during peak sunlight hours.

Usually here in SoCal my charge controller is in float mode by noon so it makes me want to get rid of some energy since I have the rest of the day to recover it.

A pure sine wave inverter seems to not be needed with a Luna charger. When on the road my cheapie mod sine wave inverter powers up the charger just fine. But for most things, pure sw is the way to go for sure. Solar=clean riding, as clean as it gets anyway!

Hello,

Good idea to solar charge, but

I would use a grid tie inverter, a cheap one.

They are not hard to come by at least in Europe,

In the day, all the electricity produced by the panels will be available to the house. All the electricity not used is just not "produced".
You can plug your bike on the house grid, it will use the solar energy. All your appliances used within the day will do too, that should save you quite a bit if especially if you make sure you run appliances that are quite energy demanding during sunny days.

Plus no need for a crappy battery system and a not-good-for-chargers modified sinewave inverter.

Here is a video update of my system https://www.youtube.com/watch?v=TRnkC41b-Hc

I went to a pure sine wave (24v 1500watt Cotek $270) inverter, because I didn't like the noise the cooling fans made on all my bike chargers. I have a total of 4 panels now with MUCH better angle and placement. I also have 2 100amp fuses and 2 10 amp fuses. The entire system has been converted from 12v to 24v 2s+2p with matching configuration on the panels. [youtube]https://www.youtube.com/watch?v=TRnkC41b-Hc[/youtube]

titooon2014 said:

Hello,

Good idea to solar charge, but

I would use a grid tie inverter, a cheap one.

They are not hard to come by at least in Europe,

In the day, all the electricity produced by the panels will be available to the house. All the electricity not used is just not "produced".
You can plug your bike on the house grid, it will use the solar energy. All your appliances used within the day will do too, that should save you quite a bit if especially if you make sure you run appliances that are quite energy demanding during sunny days.

Plus no need for a crappy battery system and a not-good-for-chargers modified sinewave inverter.

Click to expand...

Thanks for the insight, but here in America, once you attach a solar setup to the grid you are now subject to code. This involves having someone certified to attach grid tied system come do it for you. Also you have to pay SDG&E to come out an install a "special" meter that could run backwards.

I am more of a tinkerer, who realizes I'd rather store all my electricity in my transportation batteries. Lets face it, Im not making enough power to really help anybody but myself here.

Hello st35326

I am a tinkerer as well especially in the field of solar energy and weird battery configurations ...
Far from me to suggest you to go through the crazy net metering application !

I tried to find something about self consumption in the US and its legality but can't find anything. In Europe it can be annoying but most countries allow it as long as your inverter is certified.

I think I didn't really explained well the technicals of it.

You are not going to resell any electricity to the Grid, nor do modification to your existing system. All you will have is an inverter that plug to your panel, and directly to a standard 110V plug.The inverter is design to allow the energy to flow if you are using this energy (slow down your meter), and will just shut down production if no energy is in use. Zero modification needed.

Except buying a microinverter that would cost around 200$ (not sure on 110V models)

Your AGM batteries will not last longer than a year or two if they are used. You likely loose about 20 to 30% of the energy that your panels output because of them.

I believe you would have helped yourself much more with a grid tie inverter in self consumption than with your actual system, but I understand that most people are not aware of these new ways of using solar yet.

My advice is therefore; if you want to solar charge your bike and you are in a grid tied house, consider the two panels-one micro-inverter solution which is more economic, more reliable, and will get much more usable energy for you out of those panels. Make sure of the legality of that part if you really care, but using proved inverters is totally safe and need no special mod of the house grid.

btw it s not clear to me, do you have 4x400W or 4X100W of panels ?

titooon2014 said:

Hello st35326
My advice is therefore; if you want to solar charge your bike and you are in a grid tied house, consider the two panels-one micro-inverter solution which is more economic, more reliable, and will get much more usable energy for you out of those panels. Make sure of the legality of that part if you really care, but using proved inverters is totally safe and need no special mod of the house grid.

Click to expand...

Thank you for your kind recommendation. From the people Ive talked to recently at ATON and Tesla the future is in storage. But to be honest, Im perplexed by people with solar and no way to store it. Brown outs are very common here in Socal, 4 years ago I was without grid power for 39 straight hours. So I went out and bought a Honda generator. The only issue with that is I didn't realize the gas stations couldn't pump gas at that time. Never again.

Also, those are very high quality batteries taken out of a huge APU (Ive got nearly unlimited access to replacements). But I believe in 2 years they will be just fine. If they are not I will build or have an even bigger battery made of 18650 or used Tesla modules.

The purpose of this hobby system from the start was to charge electric vehicles and learn a little. Not to run a home or be tied into the grid.

After 24 volt conversion 2s+2p

Here is how I solved that ground fault issue (even though the inverter is grounded to its own 8ft copper covered rod the Leaf Charger doesn't recognize it). Yellow plug and a pair of 100k ohm resistors in the other outlet.

Ive since went to some thicker 2/0 cables and 1/4" batter bus bars for the close terminals

I had occasion to ponder the whole "solar with no storage" thing last week. For about 3.5 hours the grid went down (Idaho Power), and though I currently (love that pun) have over 13,000 KWH "on the books" as a credit with IP, I found myself sitting in the dark! This is rare, very rare, here. No biggie, reading by candle light and going to bed about an hour early did the trick. Still no desire or perceived need to add battery storage, these events are too rare and short lived to bother with. My situation and location of course different from others, but IF the grid goes down for, say a month, we as a society will have bigger problems then using candles to read by . I'm not too sure I'd want to be the only lite up place if all hell breaks loose, as I don't have stockpiled weapons and it may make me a target.! A few hours, a few times a year ( here, at least) of no power is a non event for this 28 yeah off gridded, now happily grid tied electrical consumer (producer).

Hey st35326,

I think no need to be perplex of people with solar and no batteries though, they are not doing solar to be offgrid at all, nor most off them do even actually understand how it works, as nowadays solar has been sold has a good money investment to people that are eco minded (or even sometimes only $$$ minded).

Regarding my comments on your installation, my perspective is very much on energy savings and environmental impact, that is also why it sometimes go a bit against some diy concepts... I am always very enthusiastic to see people try solar, but I also try to make sure that the concept is not green washed. Solar can be misused to the point that fuel*based electricity can become cleaner...

If I have a look at your installation, 800W of panels in south California should produce around 1,300kWh per year if I am not mistaking. Let 's say you re charging 1kWh a day, which should be around 20 miles per day with a bomber. I am assuming, if you got real numbers I ll be happy to update my calculations.
That means that you ll be using 370 kWh per year, or about 1/3rd of the energy that you could potentially produce.

Considering a solar panel takes about 3 years in a nice weather to return back the energy needed to manufacture it, 4 x 200W of panels would need around 4000kWh to manufacture. I
If you re doing 1kWh of charge a day, it will take about ten years for you to get back from your panel what they have needed for their manufacture . If we had the batteries, inverters, well at the end the system may not be "environment friendly" than charging directly from the grid. But that s a good system to understand how solar works.

Right now I just setup up a system with the exact same purpose as you, charging with solar energy my bike. I will go for two 48V batteries that I can easily switch, and a couple of panels combined with a solar MPT 7210A boost charger. Mostly because I have the batteries, but also because I dislike the inefficiency of DC to AC to DC conversion, as well as lead acid batteries in solar systems (two years average lifespan for people that I know, surely you can push it to 10 but most people don't).