An engineer came into the office today who will remain nameless mainly because I forgot his name. He told me of hijinks at the Dayton Hamvention in which he rigged a portapotty’s seat with conductive tape, a dc flourescent lamp driver, and a small solar panel on top of the ‘loo. When sunlight hit the panel, the seat became… Well, the least pleasant portapotty seat ever.
Well, this is new. Years ago, Heart Interface Corporation made a really nice line of renewable energy and vehicle ac inverters and inverter charger units. At some point, the company became Trace Engineering, which was then bought out by Xantrex, who promptly worked hard to make most of the better products and engineering go away in favor of nasty Chinese rubbish. 😛
Well, Heart Akerson is still around today in Costa Rica, and his new company, Heart Transverter, has a pretty fun product going.
Basically, it’s one green 2KW box of switching converters, software defined and highly programmable, with two dc input/output busses, one +50VDC output, one ac input, and one ac output… and it does… anything you want it to, including serving as a grid tie inverter, pv controller, charge control ….
A companion unit can be used for sophisticated load monitoring and control of six circuits.
It is designed and manufactured in Costa Rica, which is pretty amazing in itself.
The brains of the system are on a small remote control unit about the size of a sandwich, with a usb interface for programming.
Believe me, I’m most curious and intrigued. I didn’t get to see it running today, sadly. I’d love to see this in action.
I should add that the Heart Transverter logo is pretty cool. Yeah, I have a little obsession with how neat the old Heart Interface logo was 😛
By “shunt regulation”, this means they basically short out the input from the solar panel.
They’re very simple. There’s nothing to adjust, nothing to do but just hook it up and go. A small red LED on the top indicates that the solar power input is present and the batteries are charging (it goes out when the batteries are full and the controller is shorting out the output). The entire unit is “potted” in an epoxy filling and very moisture resistant – great for marine applications and severe humidity exposure.
Here’s one controller where you REALLY need to make sure that you’ve sized it correctly. Make sure that the total short circuit amperage (Isc) on your solar panels is lower than the controller’s rating… or you WILL blow the poor thing sky-high. Other than that, it’s pretty much set it and forget it. The switching is very slow, and the controllers are unlikely to generate any RFI. They’re very popular with our customers.
Click the block diagram to view it full size. This is what’s inside the unit. Please be sure you hook up the battery leads with the correct polarity, otherwise the controller just… ceases to be. The few damaged ones I’ve ever seen wound up failing with the battery terminals shorted. If proper fuses are used*, this would just blow the fuse between the controller and battery, preventing any damage or overcharge.
The AUX relay shown in the block diagram is provided on units with a low voltage warning/disconnect.
* Please properly fuse your system or I will throw things at you.
I’ve been having fun with this AIMS Power PWRIC300012W while pretending to be productive here at the office for the last couple of days.
Franklin from IndoorGenerator sent this unit over for me to play with, and I’ve found it to be very good. The unit combines a 3000 watt modified sine wave power inverter, automatic transfer switch, and 30 amp smart charger all in one nice, compact, lightweight package.
Yesterday I beat the holy splunge out of it with various test loads including a portable air conditioner and large 1/3 horsepower AC motor, and ran it at 2.8KW output for the better part of an hour. It barely even got warm to the touch.
From my testing, I found that the inverter only has two weaknesses to it.
First, like any high frequency switching type inverter, it can sometimes run out of power and turn off suddenly while trying to start loads with a large inrush current. This includes large halogen/incandescent lights, large motors, and compressors. If you’re starting such a beast off a switching inverter, it should be the first thing to be turned on, and any other loads should be removed before attempting to restart the large motor/light.
Second, the transfer switch isn’t instantaneous. The power goes off for about a second during the transfer from battery to AC or AC to battery.
A very useful little LED meter is present on the end of the unit next to the outlets. By pressing the button next to it you can select whether to view the battery voltage, DC input amperage, or AC output wattage in Kw. While AC power is present and the unit is charging the batteries, the output Kw and DC amperage both show as zero. I would have liked to have a DC current measurement visible during charge like the Xantrex TR series provides, but I’m not gonna complain much about it.
When the inverter goes into overload, the LED display on the end shows “E01″. I also managed to get the inverter to glitch a couple of times – weird things happened like the battery voltage reading coming back as ” 0.4″, or the inverter shut down and showed “Err”. Both of these problems went away as soon as I replaced a 1 AWG battery cable in the test setup which was becoming stinky hot! Oops. Too much voltage drop!
As the inverter begins to get near maximum power output, the peak to peak voltage begins to fall a bit. The unit compensates by shortening the 0-volt pauses on each cycle to maintain 120Vrms through manipulation of the duty cycle. Lights will not change brightness, but some AC induction motors may become weak as the wave approaches being a 120V peak to peak square wave. I noticed this only after applying around 2.7KW of load. The Daewoo portable air conditioner I was running did not show any problems with this, but a large industrial fan (of doom) began to slow down a little.
The charger is rated at 30 amps output. I clocked it at 33-34. It is, interestingly, built on its own board inside the top of the unit. This is a lot different than the charge system in the Xantrex Freedom series units I’m used to refurbishing, on which the same (massive) transformer and transistors are used to convert and regulate the current for charging. The internal 3-stage charger works fine on flooded cell batteries, but the absorption voltage got too high for a gel battery. I measured 14.82VDC. This may be in range for AGM batteries, however — check your battery manufacturer’s recommendations!
Today, I popped the top off and started looking around inside.
The build quality is very nice. It appears that the lower board is in charge of converting 12VDC to 170VDC. The board at upper right contains the AC transfer circuitry, a current sense transformer, and an H-bridge to chop the 170VDC into modified sine wave. The board at upper left is the charger.
The charger board has a jumper (JP1) located on it. Removing JP1 and turning on the charger activates equalize mode (about 15.3VDC). The small green LED located near JP1 comes on when the charger is in absorption or equalize mode. Unfortunately, significant disassembly of the unit is needed to access JP1, and activating any function of the unit while it’s open like this will expose lethal voltages to the user… so let’s just say that until a switch is brought out to the end panel of the unit, this feature is not Ready For Prime Time. AIMS didn’t even know the jumper was there! I only figured this out as I tried toggling the jumper to see if it was there to reduce the voltages for use with gel batteries.
The cooling fans at the end of the unit run whenever the charger is active, and otherwise… very rarely. It barely gets warm at all while in invert. All of the transistors that have any significant amount of current across them are heatsinked to the extruded, finned alumimum chassis. This is a design borrowed from high power car audio amplifiers, which have to put up with being wedged in all sorts of weird ways into hot car trunks with little air circulation.
My final verdict: If you’re looking for a good low-cost, lightweight modified sine wave inverter/charger, this is probably just what you’re looking for. If you’re running any large motor loads, however, be prepared to go over and reset the inverter when they fail to start.
If the cost and weight aren’t that much of an issue, I’d step up the Xantrex Freedom or Xantrex TR series; they cope with starting large motor loads by just throwing everything they’ve got at it, current limited only by the inductance of the transformer. The motor makes hilarious sounds and the inverter output voltage dips during the ordeal, but it’ll start the motor, whereas a lightweight switchmode inverter like this will just go “Noooo! OVERLOAD! Now you get to come over here and reset me! HA HA!” Plus, the Freedom and TR have a much stronger charger.
Or, “Now presenting, the all new for 2011 International Rectifier PwndFET Transistors”
I suspect this happens when someone reverses the battery leads on a Xantrex Freedom series inverter. The IRF1010E HEXFETs are blown to bits! On the power board for a 1000 or 1500 watt unit (they both appear to be the exact same board), there are ten on each side.
The symptoms are usually an inverter which goes through the right motions of going into charge and invert, but no output is seen. Sometimes, the unit even makes the right sort of sound as if it were going into charge/invert. Inspection of the FET board will reveal… this.
The other devices on the board appear unaffected. Coming soon: an experiment to see what happens when the IRF1010E’s are replaced! Does this lead to a perfectly working board… or just an object which remains a paperweight? Stay tuned…
The designer of the IndoorGenerator power units just dropped by here at Sun a few minutes ago. Their products are really interesting, especially for those of us down here in the Hurricane Belt.
Their product is, in a sense, like a giant UPS. Sealed maintenance-free lead-acid batteries are paired to a power inverter/charger unit in a nice cabinet. It’s also possible to get a unit from them which features a solar charge controller, and an outdoor rack to pair a couple of nice big solar panels to the system for off-grid operation!
Now, you see where I said “nice cabinet”? I mean it. Go look at their page for the PowerCubes – they look like a piece of fine furniture. You could use one as a nice end table or coffee table.
They also make some less aesthetically fancy but very functional UPS systems for commercial and office use. He was talking about using Outback Power inverter/charger units inside some of his systems, and those would be awesome for such use – they produce very clean power and transfer back and forth perfectly.
Well, these are strange indeed… FEIT Electric makes these 12 volt CFL twist light bulbs. Put them in a socket, apply 12v, and they light up, right?
Well, they’re… uh.. picky.
If the power does not come on INSTANTLY, like, from 0v to at least 11v in a few milliseconds, the bulb fails to light and something inside the ballast trips out. My guess would be a PTC (polyfuse). You have to wait a couple minutes then try again — and hope your power holds up THIS time… A voltage brownout that causes the bulb to dim out seems to also trigger this.
This could be trouble on a lighting controller that doesn’t turn them on instantly, or in vehicles where the power may dip due to cranking the engine, etc…
I think I’m definitely going to say that LED bulbs would be preferable to these. I mean, they work, but that behavior is just so weird!
Modified Sine Wave HORROR! This is what I got off an inverter with a bad output filter. I believe this is proof of why you should invest in a true sine wave inverter if you’re running anything other than lighting and a refrigerator (note: a refrigerator with electromechanical controls — not an electronic control system.)
No, the scope isn’t lying here… see the last pic…
I almost missed this because I had a resistive load on the inverter. Apply a resistive load and it looks like this. Apply an inductive load and it still has those ugly spikes.
They really are that bad.
Set to trigger on the very start of one of those negative pulses. What you’re looking at is essentially a DC offset of -170vdc… with THAT on top of it. YES, THAT IS 200 VOLTS/DIV. HOLY ASS, BATMAN.
Ok, that’s it, I’m tired of the Internet. The ipv4 crash? Speculative hoarding of netblocks, no doubt. Net neutrality? Uhh, seriously? Egypt’s government running scared and cutting off electronic communications to delay the inevitable? Verisign and the U.S. government playing around with wielding imaginary and annoying power with the DNS system? Yeah… No more.
For years, there have been mesh networks run in various places, usually a small local system. These networks can use a variety of link types; wired Ethernet, wireless radio, point to point microwave, fiber, etc. These networks are self-healing in the event of link failures or obstructions.
This is in sharp contrast to the topologies in most current commercial networks used to connect end users to the Internet, in which cost engineering has dictated that a hub and spoke model be used.
This usually kind of works, but has some major flaws. First, traffic may be needlessly routed over very long paths between major backbone links simply because two geographically close locations do not have any option for a direct link.
Second, if major backbone providers experience link failures or simply decide to “de-peer”, massive routing problems can affect millions of users. I still remember the day Level3 and Cogent came apart… I couldn’t get my e-mail for the better part of a week, as the routes were simply not there.
So, enter Owlnet. The name may or may not have been inspired by the works of a certain author whose series of novels stimulated the imaginations of a world alike, and brought her from rags to riches. By the way, if she says he is, Dumbledore is gay. Arguing this is hilariously illogical.
Owlnet shall consist of a networking layer, using a mesh network that may be deployed using whatever network hardware is available, and a services infrastructure. Wireless lan, ethernet, and even tunnels over the existing Internet may be used. (Ideally, the tunnels will be phased out as the system gains coverage.)
Dare I say that, at least for my point of view, is the easy part. The goal is to have firmware and software available to allow Owlnet nodes to be run on flashable home routers in the sub-$100 proce range, as well as on PC and server architectures.
The services infrastructure will require quite the creative planning. One of the goals I see having is an independent dns system, as well as the ability to route out of the system via exit nodes to the existing Internet, similar to Tor’s onion router system. This could be set to different personalities, everywhere from “use the closest and most convenient node” to “INVISIBILITY CLOAK!”.
The independent dns would be an interesting challenge. Ideally it should never fall under the same curse of greed that has afftected the system used on the Internet, and should be reliable and easy to use for registering resources, yet resistant to abuse. For instance, it should prevent a user from easily holding large numbers of domains for profit from resale, or squatting on existing names and trademarks. Unfortunately, I also want to avoid putting one small group in control, so this does create a bit of a paradox when it comes to how the system should be managed.
IPv6 should be used on this system. We all know by now what happens to a small namespace.
Discovery and search are two other interesting points to explore. I want the system to have a phonebook of sorts for personal contact, as I envision connecting ip telephony and instant messaging as two major applications. It should be possible to find someone via personal connections through a unique identifier, but also by more traditional means like by name and location, or via personal networks as is done with Facebook and other social networks.
The ultimate goal is to have a network that’s very usable and not dependent on any outside infrastructure. The nodes could literally be little solar/wind powered units you can toss in high locations and let it all run. Where a gateway to the existing Internet is desired, they could be connected via home or office connections as needed.
Come to think of it, this sounds a lot like HackMiami’s “Post-Apocalyptic Communications” concept. Well… let’s get it going 🙂
Power (W): 190 Watts
Open Circuit Voltage (V): 36.00 Voc
Short Circuit Current (A): 7.42 Isc
Maximum Power Voltage (V): 28.60 Vmp
Maximum Power Current (A): 6.64 Imp
Now, here’s what these mean to you!
First off, the Open Circuit Voltage (Voc). This is the voltage you will see present at the solar panel’s output when it is exposed to full sun and is not loaded. While this is not really relevant to the panel’s power output, it should be taken into consideration for two reasons: First, you should ensure that any equipment connected to the panel (meters, charge controllers, etc) is capable of handling the full Voc of the solar panel or the string of solar panels connected. Otherwise, equipment damage may occur when the sun hits the panels and they’re not loaded down. Consult the documentation on your charge controller if in doubt. Also, for your safety, be sure that any overcurrent protection devices or disconnect switches are rated for Voc or higher! Upon unpacking and installing your panels, if you’re lucky enough to get full sunlight hitting them, check the open circuit voltage – it should be close to Voc. If it’s too low, the panel may have a problem or be miswired (check the junction box).
Short Circuit Current (Isc). This measurement is useful for testing the panels and determining the sizing of your wiring and controller. Set your multimeter to amps, and connect the leads across the solar panel’s output terminals. In full sun, you should get Isc. If you do, the panel is operating correctly. Any wiring to the solar panels, and the charge controller itself, must be capable of handling the Isc of the array. Do not expect to load the panel down to Isc in normal operation, as you will be getting almost no voltage and extremely reduced power. (See I-V curve below!)
Maximum power voltage (Vmp) and amperage (Imp). These levels are very important to consider in selecting panels and components for your solar energy system! In short, please keep the voltage as close to Vmp as possible. The reason for this is that the solar panel has a certain internal impedance, and you will only receive maximum power when the panel output voltage *under load* is allowed to remain near Vmp. If you load the panel down to a lower voltage, it will become severely inefficient.
If you are using the solar panel with a conventional charge controller to charge lead-acid batteries, the ideal Vmp will be near the absorption charge voltage for your batteries. If you are using an MPPT charge controller, Vmp should be anywhere within the controller’s MPPT tracking range. This may be an extremely wide range of voltage, allowing you a lot of flexibility in choosing panels!
To illustrate the importance of the Vmp point, see the above I-V curve and power curve for a solar panel. Note that the power curve tapers down towards zero as the voltage falls below Vmp, and abruptly falls off as the voltage approaches Voc. If you buy solar panels and operate them too far from Vmp, you might as well be throwing money down a hole.
If you have an MPPT charge controller, it will periodically sweep the array voltage to find Vmp, which actually varies a little with different sunlight levels. For the best possible power output under all conditions, use an MPPT controller. The only exception I should point out: if you are using HF radio equipment, the switchmode boost/buck converter inside an MPPT controller may cause excessive noise on the receiver. Consider using a simpler charge controller in this case. The Morningstar ProStar series charge controllers have an internal jumper (really, a 0 ohm resistor that you can cut) to disable their PWM charge control to reduce RF noise to minimum.
Don’t toss your system efficiency and money down the toilet – choose your solar panels wisely!