Ben is going Solar!
 

Well, I finally threw my hat over the fence...

I just ordered 480 watts of PV panels.

Where am I going to put them? I don't know exactly....
Do I have the best solar access of anyone in town? Not really.
Am I going to live totally off the grid? Heck no.

However, I am the type of person who has found that it is best to just get into something. Just start it. I can fantasize about something all I want, but once I just start something, it becomes real and takes on a life of its own.

So, here's what I have for a plan so far.
I need to rebuild my two-car detached garage. It's practically falling down. So, I will rebuild it with the roof facing south, so I can mount solar panels on it.

I already have a number of deep cycle batteries from my work on electric vehicle projects. The solar panels that I ordered are 48V nominal. I can't run a single PV panel to a single battery. I will have to gang up batteries in sets of four.

I don't have good enough solar access, or enough panels to make "Net-Metering" worth-while, but I have most of the parts needed for a battery backup system. I found out that many industrial UPSs run as 48V, the same as the panels. I wrote my buddy, Tom, who works insalvage, to keep an eye out for one for me. I immediately got a reply of "Yep, I got one right here for you..."

Combining the PV panels on the roof, with the 48V UPS, and existing batteries, I will have almost a turn-key power backup system for my house. The UPS is over 2KW, so it will easily run my fridge and (blower and controls of my natural gas) furnace.

These panels are pretty big - about three feet square each.
I also let the woman down the street know about the panels. She has a pontoon boat she is interested in converting to electric. Two panels would mount great on the roof of her boat. They would charge the batteries all week in the sun, and even add a little power to the boat while cruising around during the day.

I just mailed in a check to pay for the panels. It's a $1.50 per watt, plus a bit for shipping. I am actually splitting a pallet-full with two other people, which significantly reduces the cost of the panels and the shipping.

Once the panels actually arrive, I'll take some photos and post them.
Rest assured, I will keep you all up to date on the project.

Want to know what else is cool about 48V panels? They are perfect to charge a 48V EV with. That's right, in my fleet of wacky vehicles, I have a 1977 Citicar, which was originally designed to run on 48V of deep-cycle batteries. I should be able to charge my electric car and electric riding lawn mower straight from the sun!

-Ben

Awesome Ben! Did you get them through Swee?

Yep, that was through Swee.

I will be getting 8 60-watt Kaneka PV panels.
I still don't really know what I am doing. However, I do have a subscription to HOME POWER, and if I built an electric car, I am pretty sure I can figure out how to set up a few solar panels.

I was going to buy some of those panels..

http://ecorenovator.org/forum/solar-...llar-watt.html

http://ecorenovator.org/forum/solar-....html#post5360

But, after about a week, they canceled my order and jacked up the shipping
so that the shipping cost more than the panels..

I've heard these are cheap right now, because the manufacture has come
out with a brand new model and cleaned out their US warehouse.

Even with high shipping, these still seem like a pretty good deal.

Please keep us posted on how your project works out..

Cheers,
Rich

Great news! I hope you get the solar electrons pumping power asap:)

What's Swee?
I couldn't find Swee with Google..

Thanks,
Rich

Haha, Swee is a member of the local EV club. He owns a shop that deals in green stuff.

http://www.youtube.com/watch?v=w7DYvTwduAw

Swee is the first name of a friend of ours. He runs the FUTURE GREEN store.

I got the call from Swee yesterday that the solar panels were in.

We did a bulk order of three pallets between 4 or 5 people. The store doesn't have much of a loading zone - only the meter street parking directly in front of the store.

I wanted to get there as soon as I could, knowing the the panels were most likely just leaned up somewhere, taking up space.

Being used to "consumer packaging", I almost expected every panel to be completely covered in inches of styrofoam and cardboard boxes. Nope! These were pallet-shipped - nothing but solar panels stacked on top of each other with some heavy-duty plastic wrap to pin them all in place.

We loaded up my share of the panels into the back of my truck. They fit well between the wheel humps in the back of my Chevy S-10 compact pickup truck.

http://gallery.me.com/benhdvideoguy/...12659223450001

Today, I tested one of the panels, and then stacked them all in my garage.

In cool, sunny weather, this panel was sending out about 95 volts DC open-circuit! I'm not used to working with HIGH-VOLTAGE panels. Most of my experience with PV has been on 15 watt or smaller 12V units.

http://gallery.me.com/benhdvideoguy/...12659223480001

If anyone cares to know the specs of the panels, here's a photo of the sticker, right on the back.

http://gallery.me.com/benhdvideoguy/...12659223510001

Wow! Great looking panels! I am so jealous!

My little battery 12V battery charger panel came into and it's only about 1'x1'. :o
But, it should do the job of charging up an old car battery.

http://ecorenovator.org/forum/projec....html#post5677

And, it's UL approved! LOL!


You already know this, but just as a friendly reminder,
I want to warn you about that 97.2 VDC.. It can KILL you.
If you have to work on bare leads from a panel, make sure it's got
a sun-proof cover on it, or you are indoors.


If you decide to change the connectors (to Anderson Powerpoles?),
I would advise doing all the soldering indoors.

The reason I'm hooked on Powerpoles, is I've used them before,
Anderson Powerpoles & Accessories:
And I'm looking to use some on the charger wiring for my tracker project.

Cheers,
Rich

Always be careful working with electricity! :thumbup:

This is a step up for me. Mostly, my electric car has been running at 96V or so.
Chances are that this solar system will be somewhere between 250 and 500 volts or so. That means being a "real" electrician. No shortcuts - actually do things right. It will end up having several disconnects, etc.

This is HIGHER than household current, and DC to boot! (more sparks! More Fun!)

Covering panels when working on them is always a good idea. I learned that working with solar hot water. On a sunny day, ten minutes in the sun made panels hot enough to burn your hand on!

I remember going up on the roof to bleed any air out of my old system,
and WOW the plumbing up there was at least 200 deg F.

~~

When I was looking at those 60 volt panels, I was thinking of just using 4 of them
into resistance heaters for my hot water. (Since they are the lowest W/$ PV available).

And, I'm still interesting in the idea. So, I'm trying to get a tracking mount set up
that can carry at least 4 standard sized panels.

So, what inverters are you looking at so far?

I already have a 48V UPS system, which I got from a computer salvage friend.

A UPS combines a charger, batteries, inverter, and automatic switch, all in one unit.

If I was able to supply 120V AC to the UPS when the sun is shining, it would take care of charging the batteries, and automatically make AC from the batteries when it was no longer getting power.

Grid-tie inverters are designed to directly handle high-voltage panels (with inputs up to 500 or 600 volts!) but are costly. The most basic high voltage one I have found so far is a SunnyBoy SB700, which is just over $1000. Even then, that one has a "safety-feature" of turning off when it senses that it isn't connected to the grid. So, running AC to my UPS might not make sense/be cost effective.

If I try to charge batteries directly, I need a solar charge controller. However, most of them are designed for 12, 24, or 48v. A single panel of mine makes MORE than 48V!
Some charge controllers feature MPPT - which can lower the voltage of a panel by converting some of it to amperage, which is really what the batteries care about anyways. Of course, this is fancy technology, which costs money. The Outback Flexmax features MPPT, can can handle a max incoming voltage of 150v. That means I would need to put all the panels in parallel, because even two panels in series could potentially add up to more than 150v. This would mean more wiring, a big combiner box, etc, etc. One of those charge controllers runs about $600.

If I did get a MPPT charge controller - that would charge the batteries directly. I would use the UPS as the inverter, and my garage could go off-grid - yeah!

This might sound crazy, but
 

I've been wondering what would happen if you tied the DC input of two regular inverters in series?

http://ecorenovator.org/forum/solar-...-inverter.html


Just stack two 28V (max) inverters to get a 56V input? Put 3 or 4 of your 60W panels in parallel to feed them??

They might balance out, since all the AC outputs would be tied in parallel to the garage gird.?.

After doing a little research, it looks like the big thing that I have to watch for is Voc - Volts Open Circuit - how many volts the panel can make in full sun on a cold day.

For my panels, it can be quite high. I already measured 97 volts in full sun in 15 degree F weather.

The trouble is that MOST of the more simple solar charge controllers for 48V battery packs CAN'T handle that high of a voltage.

The MPPT Chargers CAN handle that - usually up to 150V.
There are a few NON-MPPT that can also handle a higher Voc from the panels.
The Xantrex C40 can handle up to 125 Voc, which would be enough for single panels run in parallel.

It is my understanding that plain charge controllers basically "throw-away" any extra voltage that you have. So, that extra "headroom" of voltage I have with the 67V panels isn't going anywhere. The panels would put out 67V at one amp, but only something like 58V at one amp would be going to charge the batteries.

A MPPT charger would take advantage of that extra voltage to convert to a lower voltage but at higher amperage - thus a higher amp charger for the same amount of PV panels and sun! Yea!

The only products I have seen so far that handle really high voltage (5 or 600V) are grid tie inverters. I would LOVE to just plug one panel to the next to the next in series. It would make the wiring SO much easier.

But I don't want an inverter really - I just want a way to charge batteries. So, it looks like I need to run each panel individually to a combiner box, and then THAT into a solar charge controller.

You know what would be really cool? A 600V to 48V DC to DC converter. That would solve all my problems. Any got one of those kicking around?

Another thing that I did notice about the MPPT chargers is, although they are more expensive, they usually have some sort of built-in monitoring, and aux 12V (to activate a fan, alarm, etc.) and some other built-in features.

The less-expensive NON-MPPT chargers tend to be very basic, adding a display, etc, is optional and costs extra.

DC to DC
 

Maybe find out if someone can build one for you??

DC/DC Converter, retail, wholesale, off-the-shelf and custom, 5 watts to 800 watts


Edit:
When I was looking at those 60W panels, the BZ -HV units seemed to be in my price range.
I think both the 250 & 500W MPPT -HV chargers chargers will handle 100 Vdc (I think).

MPPT Charge Controls

It looks like I got the UPS working!

I wired up 4 mis-matched batteries, which were only about half-charged, in series for 48V and ran them to the unit.

It looks like I can turn the machine on or off manually, whether it has AC connected to it or not.

Checking with my Kill-a-Watt, and a 60 watt lightbulb as a test load, the AC output from the inverter measured almost dead on at 60 hz (59.9)
Output voltage from the inverter was right about 117V AC.

I still don't have anyway of knowing for sure what the shape of the waveform it puts out is. I have heard terrible things about non-true waveform inverters and electronics like modern battery chargers. A friend of mine has an oscilioscope. Is that what is needed to check out the waveform of the inverted AC?

I would like to use the solar panels and a solar charge controller to recharge the 48V battery pack, and then use the UPS as an inverter to make AC from those same batteries. I imagine leaving the UPS OFF except when I need it for making AC.

The charging circuit in the UPS and the solar charger shouldn't interfere with each other, should they? I would think that both decide how much to charge based on the voltage of the battery. If the sun is shining, the solar charge controller would charge the batteries. If I flipped on the UPS then, it shouldn't charge the batts, because the solar charger would be raising the voltage.

On the other hand, if I was using the batteries a lot, and found that I was dropping the voltage on the whole pack, enough to want to recharge, and it is winter and cloudy for weeks, so the solar charging isn't doing anything, all I would have to do is plug in the UPS (to the existing grid-tie wall AC), and it would recharge the battery pack.

What I want to do is be able to take my garage "off-grid". Solar panels on the roof supply the 48V battery pack with power through the solar charge controller. AC power is supplied from the battery pack, as needed, through the AC outlets of the UPS.

Ideally, I would like to be able to charge the electric motorcycle, Citicar, or Metro through this system. I know the limit there is going to be how many amps those chargers take on initial draw. The battery charger I have been using has an analog pot adjustment, which can let you lower the amperage. If I just set this to less than what the UPS can supply, I think that will work fine.

An oscilioscope should show you the sine wave. I too have read that electronics can be quite finicky with cheapo inverters. Homepower magazine had a good article on this. I'm not sure how old it was though.

A UPS that's designed for use with computers, normally has a pretty clean sine wave.

If you do use an O-scope, remember to put the probe ground clip on the (round) ground of the outlet.
I've had a few students try to look at AC outlets and accidentally stick the probe ground clip on the hot side of the line.
It smokes the probe..

Be sure the scope/probe combo is rated for 120 AC-RMS Some scopes won't handle very much voltage and need a probe (w/ voltage divider) to get up to higher voltages.
120VAC has some pretty high Peak-to-Peak voltage..
Brushing up on ac circuit fundamentals


Jeepers, that modified sine wave sure looks like a square wave to me!! :eek:

http://www.bdbatteries.com/images/sinevsmod.jpg

Here's some video for you guys to get a better feeling for what I am doing.

YouTube - 48V UPS for DIY Solar PV System - Part 1

YouTube - 48V UPS for DIY Solar PV System - Part 2

Still a third video coming - it's uploaded to YouTube but not processed yet.

So far, it looks like I should be able to hook the UPS to the batteries, but just not plug the inverter in to wall power. That way it doesn't ever try charging the batteries at all, it only acts as an inverter.

I am guessing the sine wave from it will be fine, but I would still like to check it.

The next big thing is to decide on what solar charge controller I want. I need one that handles 48V battery packs, and has at LEAST a 100Voc input. MPPT would be nice, as the panels can put out fairly high voltage.

That UPS looks very much like the one I have at work under my PC desk..
I forget how many batteries it has inside, I changed them once after
I pulled the unit out of the salvage room..



Did you look at these chargers?? MPPT Charge Controls

The 500W are $200 and the 250W units are around $120 on Ebay these days.

They also make an HV (High Voltage) version of these which are good to 100VDC (or so I've heard)..


Cheers,
Rich

I took a look at the BZ solar charge controllers. They seem to be the cheapest with MPPT on them.

The high-voltage version is listed as 100Voc max input. I wonder how specific that is. I was hitting 97Voc on a 15 degree F. day. I bet my panels could break 100Voc when it's colder.

I noticed that the Xantrex and Outback MPPT chargers list 150Voc as the max input. Even though those controllers are more expensive, they do have some nice features, including remote monitoring, aux out, and built in displays listing amperage, voltage, etc.

Any of the cheaper chargers will really still need some ammeters, volt meters, etc added to the system. Lots of those things can be salvaged or had cheap, but since this is for a detached garage, being able to read all those things from inside the house sounds appealing.

There is still the possibility of some sort of DC/DC conversion to allow me to use all the panels in series, and then convert the high voltage DC to low voltage DC, and run it through a less expensive charge controller.

IIRC, those panels will have higher than normal output for the first few weeks..

I guess you could design and build some 48V MPPT boxes, but do you really
NEED maximum performance out of your panels?? Or, will they do the job with less
costly hardware?

If I am going to mess around with solar, I should actually learn about some of this stuff.

A while back, I joined the MREA and signed up for the entry-level solar hot water class. Being a member gives you a discount on the classes.

I took a look at the on-line listing of available classes. Turns out there is a PV-101 class being held about a 40 minute drive away, two days from now.

I signed up for it.

Also, I have seen that the Xantrax C-40 is a pretty reasonably priced PCM charge controller. It will handle 12,24, or 48V battery packs, and has a Voc input of up to 125V. For $125, I could buy one (no display or anything on it) add my own analog ammeter, voltmeter, etc. and be ready to go.

If I later wanted to invest in a fancy MPPT charge controller, the C-40 could then be used to charge a 12v pack with some of the other small PV panels I have kicking around. I could even mount it in my camper!

That Xantrex CM LCD Digital Display looks petty nice, but at $74 ??

I read up on the C-40 weeks ago and was impressed at what it could do.
Just for charging lead-acid batteries, it should do the trick..
IIRC it's a standard 3 stage unit.

If you want the BZ (MPPT) unit, but are worried about the 100V limit,
you should investigate your panels some more. Will they ever go over 100V when in parallel? It shouldn't be to hard to find out for sure.
I know they are in use down in Australia (on homes).

Heck, the BZ HV units may have been designed for your panels..

How did the class go? Did you learn much good stuff?

Cheers,
Rich

Yeah, it was just the basics class, but it still covered a fair amount. Lots of fun.

We got to go outside and use a Solar Pathfinder. That was kinda cool!

Yesterday, I was over at my friend, Tom's house, and got to use his oscilloscope to test out my 48V UPS.

Here's a bit of video of us playing around with it.
YouTube - 48V UPS True Sine Wave testing

It turns out that the inverter of the UPS IS TRUE SINE WAVE, (which I thought/hoped it would be) but it actually gave better AC power than what came from Tom's wall outlet!

The UPS only converts power from the 48V battery pack to AC when it senses a disconnect from the wall power. We did that by flicking the switch on the power strip. The waveform stayed very nice - no "glitch" or anything - just a seamless transition from wall power to battery power and back.

In my case, I am not really planning on using this device as a stand-alone UPS (although I do have some clever ideas for that as well...) Rather, I just want to use the inverter section of the UPS to convert power from a 48V battery pack to 120V AC.

Charging of that battery pack will be done from the solar panels through a (still undecided upon) solar charge controller.

Using the 48V UPS saves me the cost of a solar true-sinewave inverter, which can be VERY expensive. On the downside, the UPS is only designed to run 2200 VA peak, although it does have several power outlets on the back, including two 20 amp outlets.

I would also like to add an extra output to the solar charge controller, as both my motorcycle and CitiCar use 48V battery packs. Rather than charge a 48V battery pack, invert it to AC, run that to a 48V charger in the vehicle, which converts it back to DC - I could more or less run the PV panels straight to the EVs' main battery pack.

The motorcycle doesn't even have an aux 12v battery, just a DC/DC converter. The Citicar would still need a 12V charger hooked up for it's aux battery, although that could be swapped out for a DC converter as well.

For my electric Geo Metro, it would require use of the UPS/inverter because it runs typically at 96 or 108V. I would simply plug the car (with its built-in charger) straight into the UPS. In case the UPS power pack starts to run low on juice, it SHOULD automatically turn off AC to its outlets. I would want to double-check that with some real world-testing though.

Anyways, I am very excited that it looks like the UPS should work great for what I want it for. I still may add an extra fan or heat sink in it if cooling during longer run times is an issue.

Good looking wave-form! That's what I expected you would see. After looking
at the modified wave form, I was mortified.. ;) No way I would want that feeling into my PC!

How much power does the electric Geo Metro need for a medium speed charge?
It seems like a full house EV car is going to be an Amp hog.. And mostly feed at night..:eek:

The Electro-Metro would definately be the energy hog.

It uses a charger which is adjustable for 72 to 108V battery packs, and can pull up to around 1800 watts from the wall, but typically, we don't like to do that.

For the last while, I had been running the Metro at either 96 or 108 volts. Lets set the car up as 96V, because the math is so easy.

Also, we'll turn down the amperage on the charger, with 5 amps, used as an example.

At a 5 amp rate of charge on a 96V system, that is 480 watts. The PV panels I have are rated at 60 watts, and I have 8 of them.
60w x 8 = 480 watts!

Not bad, the car and the solar system are PERFECTLY MATCHED! Of course that doesn't account AT ALL for the built-in inefficiencies of inverting from 48V DC to 120vAC and the charger converting to 96+V DC again.

Also, my batteries are 95 amp-hours. (lets round to 100 to make it easy.)
If my batteries are half run down - we need to replace 50 AH of energy to fill them back up. If we are charging at 5 amps, that's ten hours of charge time.

That might be possible in the height of summer. Around the solstice I might be able to get that much. Otherwise, Its more likely that I would have to let the car sit for MORE than one solar day to get that much energy.

On the other hand, if I just have to run a couple of errands, I may only run the battery pack down just a little bit. Perhaps little enough that only 5 or six hours of solar charging would be needed.

Also, since the solar panels are routed to stationary batteries, and THOSE are hooked up to the inverter, I COULD charge an EV at night, but I would want to make sure my PV system batteries outweigh my EV batteries, and have a low-voltage cut-off to deactivate the inverter if the system batteries drain too low.

Alternatively, my electric motorcycle uses 4 55AH AGM batteries. If those are run half-down, that's only 27.5AH to replace. If the cycle is hooked directly to the solar charging system (instead of through an inverter and AC to DC battery charger) it would be much more efficient.
The PV panels basically make 1 amp each. So 27.5AH/8 amps is just under 3 and a half. The PV would recharge the cycle pretty quick - only half a day.

The Citicar (with a 48V battery pack) would be similar in charging, except that is would have a battery pack double the capacity of the motorcycle. Still only 8 hours of sunshine for a complete charge.
Again, these are all round numbers and battery voltage changes as the batteries charge, etc. so some of this will just have to be tried out in the real world, once I get all this going!

I imagine I would charge EVs from the solar system when I would be at home during the day. At night, (off-peak!) or if I need to turn up the charger (for whatever reason) I could just plug EVs straight into my wall grid-power as I have been doing so far.

PS: I just ordered a Xantrex C-40. It's only $140, has a warranty, and could be repurposed in the future, should I decide to upgrade to a MPPT charger or other system. This is just the basic version - no fancy display or remote reading - but I can upgrade to that in the future if I wanted to.

If your citicar sits at home very much I would say to have the battery pack hooked up the inverter pack as well so your inverter can use that pack when you need the power and the sun charge them when you don't need it, you might not have full range in the EV at that point so it really comes down to if you want to us your garage more then you drive.

Ryland, I thought about that too a bit.

A friend of mine (who also has a Citicar) is getting married this summer. Sounds like it might be out where there is no power.

I thought it would be pretty funny to drive a Citicar out there with the UPS and fire up a sound-system!

It would be a self-contained, portable power system that could drive itself around. He would get a kick out of that.

That C-40 looks to be very versatile and a good investment, since it can be used for other applications.

It almost sounds like you could almost use those new panels directly tied to the Metro's pack.
Is there any surface area where you could install a couple on the car itself? ;)
Too bad those things are so large!

Unfortunately, the panels are about three feet square, and only output about an amp (but at good voltage!)

I wouldn't go through that kind of trouble for only an amp of juice.

However, the Citicar has a 48V pack, and one of these solar panels might actually look good on that! Still, it would be more to make a statement than for actual charging.

I just got my Xantrex C-40 in the mail!!!!

I am now reading through the manual - all zillion pages of it. Actually, the documentation looks very good, and the controller will handle up to 125Voc.

Cool.. 125v is up there.. Forget reading all one zillion pages, just skip to the
section where the C-40 is used to charge batteries.. :)


http://www.arttec.net/Solar_Mower/Ga...ex_charger.JPG
Looks nice inside!

I guess it can work with lower powered panels too.
Solar Charger For Electric Lawn Mower

I just did a test-wiringup of the controller.

It is cold and cloudy out today, so I just did a simple 12V test in my living room.

It was rigged with a 15watt PV panel that is one of three from my Harbor Freight solar kit.

Everything works right, the little green light blinks and everything!

YouTube - Xantrex C-40 Charge controller arrives!

48-Volt Testing
 

I had a little time this afternoon, and it was nice and sunny, so I decided to see if I could get just ONE of the PV panels hooked up to the controller and a battery pack.

I wired up the panel to the C40 solar charge controller through a basic disconnect with a built in fuse.

The battery pack is just four 12V batteries wired in series. I simply put an Anderson connector on there as a manual disconnect.

Hooking everything up really was just as easy as loosening and tightening some screws. The Xantrex manual has nice clear diagrams, and easy to follow hook-up directions. The manual is even spiral-bound, so it stays open to the right page when you set it down.

I hooked everything up, and flipped the PV disconnect to the ON position.
The only thing is, there's absolutely nothing to indicate that there is power going from the PV panels to the batteries.

On the charge controller, a green LED blinks to indicate that the batteries are hooked up, and the rate of flashing indicates the relative charge.

Right now, having the optional display for the charge controller would be nice. That would show me the volts/amps/watts going through it.

For now, I will just have to scrounge up a small ammeter and voltmeter to add to the system. On the full setup, I will also need a lightning arrestor, a grounding spike, and a GFI.

Here's a video overview.
YouTube - DIY 48V Solar - One Panel Test

Thats a perfect application for something I've been wanting to work on (time, time, where does it go?). I would love to make an arduino based watt hour meter. It would read voltage, amps and also log watt hours. This would all be displayed on a nice little LCD. I just need to pickup some stuff from Tom and I'd have the components necessary to build one. I'll be picking them up this Sunday actually.

I checked the panel and batteries when I got home today (another sunny day today, yea!)

The voltage of the batteries was all around .5 volts higher than they were yesterday - so some power was getting into the batteries all day!