Incredible Prices on Solar

akrvbob · Mar 19, 2012

A local store here in Victorville, CA has incredible prices on monocrystalline solar panels.  185 Watt panel for $229140 Watt panel for $179 So if you are in the Southern California area, it might be worth the trip to pick one up. Here is there website:<a href="http://www.lightitupsolar.com/" target=_blank>http://www.lightitupsolar.com/</a>Scroll down and see the current ad. I don't know if they will ship them or not, you will have to call and get the details. 760-244-9646 Bob

ped · Mar 19, 2012

Wow incredible price. Thanks for that Bob! But it should be noted the 185w is at 36.2v which is the equivalent of about a regular 90 watt 17.5v panel.The 85w (17.3v) UL Solar ones can be gotten for $160 shipped and will give about the same charge to the batteries.

yesican · Mar 19, 2012

A friend of mine informed me that he has a friend who makes his own solar panels.  He said it requires sodering and is tedious but is doable if you have the time and patience.  Has anyone heard about how to make your own solar panels?

karl · Mar 20, 2012

checked into one of those "build your own for pennies" offers, cant remember the name, it also included "free" information on making a wind generator..... I'm grateful that they did refund my money since the savings vs quality wasn't close to worth it to me....and I have a robust do-it-myself gene. JMHO

akrvbob · Mar 20, 2012

But it should be noted the 185w is at 36.2v which is the equivalent of about a regular 90 watt 17.5v panel.The 85w (17.3v) UL Solar ones can be gotten for $160 shipped and will give about the same charge to the batteries.

While that is true, it is also testimony why you should ALWAYS buy a MPPT controller. The old PPT controllers always waste some power since solar panels start at 17 volt and go up to the 100s of volts. The voltage between 12 and 17 volt is simply thrown away without MPPT. The  higher the voltage, the more efficient the conversion process. A MPPT controller will put every amp your solar panel creates into the battery, while a PPT controller will waste some of them. Generally you will get a 25-30% increase of amps put into the battery over a PPT controller. Somehow MPPT controllers have gotten a reputation of being very expensive. That may have been true once, but now there is a very small price difference between equal mppt and ppt controllers. I use a BZ 250 MPPT controller that will handle both 12 and 24 volt panels (so it will work with the 185 watt panel for $229)  and you can order it over the Internet for about $130. I've been using mine for 3 1/2 years, works great. Bob

VanTrekker · Mar 23, 2012

Cool thread here... I'm looking at buying a charge controller to start the solar project piece by piece.  Bob, thanks for the recommendation on the BZ250 MPPT charge controller.  It's good to hear from someone who has used it for some time!

ped · Mar 23, 2012

Generally you will get a 25-30% increase of amps put into the battery over a PPT controller.

Sure, if you have 48v panels on a 12v system and run the bank down below 11.9v regularly. I'd like to see the real world proof of 1/5th of that with a normal system though. But even if you got as high as 35% gain with an MPPT from these it is still only equal to about a 115w-17.3v panel. Which calculates out to be a $1.99 per watt. So you would still be quite a bit better off saving your money on the MPPT and large high volt panels and buying two of the smaller, lower voltage panels and a regular charge controller. 185W panel $229 + MPPT $130 = $360 Gives you about 55 amps per day 2 85w panels $160 ea + PWM charge controller $30 = $350 Gives you about 80 amps per day

akrvbob · Mar 23, 2012

Ped, I don't want to offend you. But I can't let your misunderstanding about solar go uncorrected, so please don't be angry with me, I mean no offense,. PPT controllers are simply a gate that lets power through and reads the state of the battery so they aren't over-charged. MPPT controllers have a computer chip that reads the voltage coming in, and the voltage of the battery and steps the voltage down so the maximum amount of amps are being put into the battery. You are right about PPT controllers, since we have batteries that can take a maximum of 14.4  volts(we don't need to quibble about that number), everything above 14.4 volts is lost, thrown away, flushed down the proverbial toilet. However, if your battery is run down to 12 volts, it can't take more than 12 volts. Anything above 12 volts will damage it. However, a MPPT controller is designed take the 36 volt coming from the panel and step it down to the 12 volts  (or whatever the batttery will take at that moment)., What happens when you step volts down? The amps increase!! The computer chip in the controller decides how to get the most amps into the battery by reducing the voltage and increasing the amps. Okay, here is a real world example that happened to me. I saw this with my own eyes, in my camper, with my solar panel and my BZ250 mppt controller. I started small with a 50 watt kyocera panel that is rated at 17 volts. 50 watts divided by 17 = 3 amps. So your PPT controller has 3 amps coming into it at 17 volts, but because your battery is low at 12 volts, the battery can only put in 12 volts at 3 amps (anything more than 12 volts damages the battery). 12volts X 3 amps =36 watts So only 36 watts can get into my battery, everything above that is wasted, flushed down the proverbial toilet But an MPPT controller will step the voltage down to 12 volts and increase the amps going into the battery. 12 volts X 4.2 amps = 50 watts. I watched the digital display on my controller and I routinely saw 4 amps going into the battery. With an PPT controller, it would have been 3 amps, I gained 25% more. That's not theory, it is real world, I saw it with my own eyes on a 50 watt panel Okay, lets look at your 85 watt panel: 85 divided by 17 = 5amps So it puts out 5 amps at 17 volts, but a PPT controller can only put in 12 volts at 5 amps 12 volts X 5 amps =  60 watts So only 60 watts are going into the battery. But a MPPT controller will step the voltage down so all 85 watts are going in: 85 watts divided by 12 = 7 amps. MPPT controller puts in 7 amps X 12 volts = 84 watts PPT controller puts in 5 amps X 12 volts = 60 watts. THAT IS MORE THAN 35% INCREASE OF POWER GOING INTO THE BATTERY You are getting 7 amps out of a 5 amp solar panel. Is it magic? No, a computer chip steps down the voltage and increases the amps. A PPT controller simply can't do that. No power is created, power is simply kept from being wasted. I've explained this to people before and they simply could not believe it. There is nothing I can do about that. I've seen it with my own eyes, and I have read it online. Here is by far the best explanation I have seen of MPPT: http://www.windsun.com/ChargeControls/MPPT.html Check it out and maybe it will explain it better than I can. Bob

ped · Mar 23, 2012

You're whole premise is a misunderstanding of what MPPT actually is. They are a PWM (pulse width modulated) controller that does one extra function only in the 1st stage of charging. The 2nd and 3rd stage of an MPPT functions no different than any other PWM controller.Batteries can't be charged beyond their bulk stage with high current so the voltage sweep function is off until the bank gets below ~12.42v and you are just running a standard controller. Go look at Blue Skies manual. It's why they call it the "boost" phase. You can watch what is going into the battery all day. 9/10 times it's not actually the case. You have to measure at the battery what you're getting. Not what the controller says it's putting out. Next batteries do not charge at the same voltage in all phases. They charge at 14.4v in bulk and absorbtion. In the bulk phase the batteries will accept all amps that can be produced up to 1/6th the banks capacity. This is where MPPT comes in and only where it comes in. In the absorbtion phase when the bank reaches 12.45v the amps are then progressively tapered by the charger while the voltage remains constant until the bank reaches ~12.68v. Then the voltage and amps are droped to a steady 13.6v to maintain the state of charge. No charge controller is putting 12v to the battery. It is putting a nominal 14.4v. This is where the sweep begins. Then we must minus the voltage drop from the panel to the charge controller leaving you with a real world ~2-2.5v to sweep...slightly more than a AA battery. And only when the bank is significantly drawn down for the controller to function in its boost mode. So again you have your 36.2v system. 185/36.2 = 5.11 max theoretical output. Lets give you an unlikely 45% MPPT increase. 5.11 x 1.45 = 7.41 amps per peak hour of sun let's approximate to a factor of 8.8 hrs of sunlight per day 7.41 X 8.8 = 65.2 amps a day You spent $360 to get 65 amps Now let's break down the cost benefit analysis of the 85w panels with a PWM controller using the same sunlight approximation. 85/17.3 = 4.5 x 2 panels = 9 amps per hour 9 x 8.8 = 79.2 amps per day So what we see in bank charging is that we can pay the same price and lose 14 amps in actual charging with this MPPT system. This is the marketing gimmick of MPPT. You get more efficiency per watt of panel, but less actual charge per dollar spent. And that is what actually matters to the vast majority of people on a budget.Why would I pay the same price for a solar system that gives me 20% less real charge every day?

yesican · Mar 23, 2012

Brain wars!!!  If you two keep explaining your points, eventually I'll understand...its all french to me, but the more I read, the more it sinks in with at least some understanding...Thanks to you both!!!  And...Don't stop disputing...it's helping me!

SoulRaven · Mar 24, 2012

PED said: So again you have your 36.2v system. 185/36.2 = 5.11 max theoretical output. Lets give you an unlikely 45% MPPT increase. 5.11 x 1.45 = 7.41 amps per peak hour of sun let's approximate to a factor of 8.8 hrs of sunlight per day 7.41 X 8.8 = 65.2 amps a day You spent $360 to get 65 amps ================================================================== Here are the real numbers as they work out with my MPPT Controller and my 36V @ 185W output solar panel... What goes into the MPPT controller from the panel is this : 185w/36v = 5.138 amps What the MPPT controller does is convert the 36V to 12V thus causing the amps to raise 185w/12v = 15.416amps So amps are gained over a PWM controller, but the MPPT is smart and squeezes every bit of power out of the solar panel where PWM Controllers just are not capable of doing this, PWM is very old technology... Also PWM controllers are not compatible with the bigger wattage panels and make the user to do twice the work of a single panel user, not to mention the space lost... Info from the manufacturer of my controller: BZ PRODUCTS, INC. MODEL MPPT 250HV!!! Twenty Five Amp MPPT Current Boosting Solar Charge Control. (Maximum Power Point Tracking) This is a Panel/Flush Mount The model MPPT250HV is a 25 amp high performance current boosting solar control optimized for use with the Kaneka GSA211 60 watt solar panels and other systems utilizing High Voltage arrays. Through the use of advanced microprocessor control and a high efficiency power converter, power wasted in older PWM style solar controls is converted into higher charge current. The MPPT250HV allows for input voltage conversion. This increases the Maximum Power Point voltage and allows for higher boost current over wider operating conditions. You can charge a 12 volt battery from a high voltage solar panel. A high accuracy digital volt and amp meter displays battery voltage and charge current. An auxiliary 100 ma 13.8 volt trickle charger is provided to keep the engine/generator start battery fully charged. A 15 amp capacity low voltage disconnect protects the battery from over discharge conditions. Proper battery charging is maintained over a wide temperature range with the battery temperature sensor. Battery float voltage is accurately regulated. Night time battery discharge is eliminated through the use of a high efficiency Schottky diode. Maximum normalized input power to the MPPT250HV is 250 watts. Operation: When power is available from the solar panel, the MPPT250HV microprocessor measures and determines the optimum operating point of the solar panel to produce the highest charge current possible to the battery. There is no interaction between the MPPT250HV and other battery charging systems. The float voltage of the MPPT250HV is factory set to 14.1 volts. The float voltage is adjustable. When the battery voltage reaches the float voltage the red Float LED turns on. At this point, charge current to the battery will gradually diminish to maintain the float voltage. As soon a load is turned on, maximum charge current is applied to the battery. Temperature compensation adjusts the float voltage to properly charge the battery over a wide temperature range. When the battery is warm the float voltage will drop and when the battery is cold the float voltage will rise. The MPPT250HV is well suited for flooded, deep cycle and gel type batteries. A low voltage disconnect is included to protect the battery from excessive discharge by automatically turning off a load, such as lights that may have been left on. Load is disconnected when the battery voltage is 12.0 volts or lower. When the batteries are recharged to 12.6 volts the low voltage disconnect reconnects the load. The yellow LED on the face of the MPPT250HV is lit when the load is connected. Operation of the low voltage disconnect is fully automatic. Maximum low voltage disconnect load current is 15 amps. Do not connect the low voltage disconnect to inverters. <table border="1" cellpadding="7" cellspacing="0" width="532" align="center"> <tbody><tr> <td colspan="2" height="24" valign="top"> MPPT 250HV Standard Features: </td></tr> <tr> <td height="26" valign="center" width="39%"> Ã¢Â€Â¢ Current boosting </td> <td height="26" valign="center" width="61%"> Ã¢Â€Â¢ Digital volt and amp meter </td></tr> <tr> <td height="18" valign="top" width="39%"> Ã¢Â€Â¢ 12volt operation </td> <td height="18" valign="top" width="61%"> Ã¢Â€Â¢ 25 Amp charge current </td></tr> <tr> <td height="18" valign="top" width="39%"> Ã¢Â€Â¢ PWM float control </td> <td height="18" valign="top" width="61%"> Ã¢Â€Â¢ fully automatic operation </td></tr> <tr> <td height="18" valign="top" width="39%"> Ã¢Â€Â¢ Easy installation </td> <td height="18" valign="top" width="61%"> Ã¢Â€Â¢ Low voltage disconnect </td></tr> <tr> <td height="18" valign="top" width="39%"> Ã¢Â€Â¢ Five year warranty </td> <td height="18" valign="top" width="61%"> Ã¢Â€Â¢ Auxiliary battery charger included </td></tr> <tr> <td height="17" valign="top" width="39%"> Ã¢Â€Â¢ Flush mount </td> <td height="17" valign="top" width="61%"> Ã¢Â€Â¢ Battery temperature sensor standard </td></tr></tbody></table> <div align="center"> <div align="center"> <table class="MsoNormalTable" style="border-collapse: collapse;" border="0" cellpadding="0" cellspacing="0"> <tbody><tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: silver; background-image: none; background-repeat: repeat; background-attachment: scroll; background-position: 0% 0%; -moz-background-size: auto auto; -moz-background-clip: -moz-initial; -moz-background-origin: -moz-initial; -moz-background-inline-policy: -moz-initial;" colspan="5"> SPECIFICATIONS:</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> PV Charge Current:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 25 amps continuous</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Digital Meter:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Ã‚Â½" LCD display</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Surge Current:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 35 amps for 10 min.</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> DC Volts Range:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 0-99.9 volts Ã‚Â±0.5%</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Array Voltage Open Circuit:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 100 volts max.</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> DC Amps Range:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 0-99.9 amps Ã‚Â±0.75%</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Input Power Max.:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 250 watts</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Temp. Comp.:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> -18mV/Ã‚Â°C nominal</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Input Power Min.:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 68 watts</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> PV Input:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 67 volts nominal</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> PV Input Voltage:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Auto-ranging</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Reverse Current:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 0.01 amps nominal</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Min. Battery Voltage:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 10 volts</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Min. Battery Capacity:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 100 amp-hours</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Operating Temp.:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> -20 to +60Ã‚Â°C</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Storage Temp.:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> -30 to +70Ã‚Â°C</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Float Voltage Range:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 12.5 to 15.5 volts</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Float Voltage Preset:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 14.1 volts</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Operating Current:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 0.15 amps nominal</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Float Regulation:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Ã‚Â±0.05 volts nominal</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Wire Size:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> #12 AWG max.</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Mounting:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> #6 screws</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Efficiency:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> > 95% at 20 amps</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Finish:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Black powder coat</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Weight:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 2 pounds</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Auxiliary Charger:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 13.8 volts at 0.1 amps</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Lightning Protection:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 1000 watt MOV</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> Dimensions:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 7.8" x 5.1" x 2.5"</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> LVD Current:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 15 amps max.</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> LVD Current:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 20 amps surge</td></tr> <tr style=""> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> LVD Disconnect:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 12.0 volts</td> <td style="border: medium none rgb(212, 208, 200); padding: 0.75pt 4pt; background-color: transparent;">  </td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> LVD Reconnect:</td> <td style="border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) silver; border-width: medium medium 1pt; padding: 0.75pt 4pt; background-color: transparent;"> 12.6 volts</td></tr></tbody></table></div> <a target="_blank" name="mppt500"></a>Specifications subject to change without notice. <a target="_blank" style="" href="http://www.windandsunpower.com/BZ_files/MPPT250-Installation Manual.pdf">Full specs/Owners manual</a></div> Manufactured In USA by: BZ Products, INC. This item is Serviced by BZ Products Inc.

VanTrekker · Mar 24, 2012

Here's my two cents... I just bought an MPPT controller.  The plan is to add a single solar cell. I think a lot of the discussion can be summed up by saying if you're using a higher voltage solar array (closer to 30 volts input), you might benefit more from MPPT.  If you're using the 12V ones that run about 17V you might not benefit as much from MPPT.    I'm going to stick to one large panel so the discussion of what is better - one big panel with MPPT or 2 smaller, lower voltage panels (with PWM) isn't really an issue for this installation.  Despite some reservations about stuff made in and sold by Chinese companies, I decided to try a Chinese MPPT charge controller.  The decision was based on features and cost.  I wanted something with an LCD readout, not just LEDs.  So, what the heck... I ordered one from Ebay.  It will be here in a couple of weeks.  <img border="0" hspace="0" alt="" align="left" src="http://thumbs1.ebaystatic.com/m/mPMlMN63NSINg-0MDjBJkPA/140.jpg">It's wasn't a huge amount of money ($167 / including shipping)...   We'll see how it turns out.  The only real gamble is whether or not it boils the AGM batteries dry...    The plan is to babysit it quite a bit at first but would still do that with any of the brands...  I've got a voltmeter built into the wall and periodically check it like a mother hen.  I keep a chart handy to refer to the battery charge condition and monitor what charging phase is occurring.  Here are some specs for the controller.  (I bought the PCM-3012)  It will be interesting to see how it works...  <table style="width: 414pt; border-collapse: collapse;" border="0" cellSpacing="0" cellPadding="0" width="552" height="563" v:shapes="_x0000_s1033"><tbody><tr style="height: 15.75pt;" height="21"><td style="border-width: medium medium 0.5pt; border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) black; width: 139pt; height: 15.75pt; background-color: transparent;" class="xl63" height="21" width="185"></td><td style="border-width: medium medium 0.5pt; border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) black; width: 146pt; background-color: transparent;" class="xl64" width="195">PCM-3012</td><td style="border-width: medium medium 0.5pt; border-style: none none solid; border-color: rgb(212, 208, 200) rgb(212, 208, 200) black; width: 129pt; background-color: transparent;" class="xl64" width="172">PCM-3024</td></tr><tr style="height: 15.75pt;" height="21"><td style="border: 0.5pt solid black; width: 414pt; height: 15.75pt; background-color: olive;" class="xl65" height="21" width="552" colSpan="3">ELECTRICAL SPECIFICATIONS </td></tr><tr style="height: 30pt;" height="40"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 30pt; background-color: white;" class="xl68" height="40" width="185">MPPT Range @ Operating Voltage</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 146pt; background-color: white;" class="xl69" width="195">15V~33V@12V</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 129pt; background-color: white;" class="xl69" width="172">30V~66V@24V</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Max PV Input Voltage</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 146pt; background-color: white;" class="xl69" width="195">50V</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 129pt; background-color: white;" class="xl69" width="172">75V</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Max PV Input Current</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">18A</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Max PV Input Power</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 146pt; background-color: white;" class="xl69" width="195">300W</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 129pt; background-color: white;" class="xl69" width="172">600W</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Recommended Battery Type</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">Sealed Lead-Acid Batteries, AGM or Gel</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Nominal Battery Voltage</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 146pt; background-color: white;" class="xl69" width="195">12V</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 129pt; background-color: white;" class="xl69" width="172">24V</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Max Charging Current</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl72" width="367" colSpan="2">25A</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Ripple Voltage</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2"><Ã‚Â± 1V</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Max Efficiency</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">0.97</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Standby Power </td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 146pt; background-color: white;" class="xl69" width="195"><1W</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 129pt; background-color: white;" class="xl69" width="172"><2W</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Charging Schemes</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">3 stages, bulk, absorption and floating</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 31.5pt; background-color: white;" class="xl74" height="42" rowSpan="2" width="185">Protections</td><td style="border-width: 0.5pt 0.5pt medium medium; border-style: solid solid none none; border-color: black black rgb(212, 208, 200); width: 275pt; background-color: white;" class="xl75" width="367" colSpan="2">Battery Reverse Polarity, Reverse Current at Night, </td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: rgb(212, 208, 200) black black; width: 275pt; height: 15.75pt; background-color: white;" class="xl78" height="21" width="367" colSpan="2">LVD/LVR, HVD/HVR, Overload (>110%)</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">LCD Indicator</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">Solar and Output Power, Battery Voltage, Charging Current, and Fault Conditions</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">LED Indicator</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">3 LED</td></tr><tr style="height: 15.75pt;" height="21"><td style="border: 0.5pt solid black; width: 414pt; height: 15.75pt; background-color: olive;" class="xl65" height="21" width="552" colSpan="3">GENERAL SPECIFICATIONS </td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Conformity / EMC</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">CE / EN61000-6-1, EN61000-6-3</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Operating</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">-20Ã‚Â°C~55Ã‚Â°C </td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Enclosure Type</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">Indoor, IP43</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Working Humidity</td><td style="border-width: 0.5pt 0.5pt 0.5pt medium; border-style: solid solid solid none; border-color: black; width: 275pt; background-color: white;" class="xl70" width="367" colSpan="2">100%RH Max Non-Condensing</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Dimension</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 146pt; background-color: white;" class="xl69" width="195">135*170*57.5mm</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 129pt; background-color: white;" class="xl69" width="172">200*170*57.5mm</td></tr><tr style="height: 15.75pt;" height="21"><td style="border-width: medium 0.5pt 0.5pt; border-style: none solid solid; border-color: black; width: 139pt; height: 15.75pt; background-color: white;" class="xl68" height="21" width="185">Weight</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 146pt; background-color: white;" class="xl69" width="195">0.92Kg</td><td style="border-width: medium 0.5pt 0.5pt medium; border-style: none solid solid none; border-color: black; width: 129pt; background-color: white;" class="xl69" width="172">1.85Kg</td></tr></tbody></table>WARRANTY:   What warranty?  Good luck, dumb man who live in van!  --  Just kidding...  --- Van Trekker

akrvbob · Mar 24, 2012

Okay, here is where we are missing it.

So again you have your 36.2v system. 185/36.2 = 5.11 max theoretical output. Lets give you an unlikely 45% MPPT increase. 5.11 x 1.45 = 7.41 amps per peak hour of sun

You don't divide the 185 watts by 36 volts, you divide it by 12 volts. 185/12=15.4 amps per hour. Why do we divide it by 12 instead of 36? Because the MPPT controller converts it to 12 volt and increases the amps appropriately. Lets make a comparison. If you plug a 100 watt bulb into an inverter do you divide 100 by 110 volts so it draws .9 amps, or do you divide it 12 because it is coming out of a 12 volt battery. Of course you divide it by 12 so it is drawing 8.3 amps. Why? Because of Ohms law that says that if the volts coming from the battery go up (from 12 to 110 volt), then the amps have to go down (from 8.3 at the battery to .9 at the light bulb). MPPT is an inverter in reverse, it reduces the incoming voltage (from 36 at the panel to 12 at the battery) and increases the amps (from 5.1 at the panel to 15.4 at the battery). A regular  controller does not have the function to reduce the volts , so all voltage (and the amps that go with them) above 14.4 is simply lost. For that reason, in my opinion, everybody should spend the money and buy an MPPT controller.  Bob

VanTrekker · Mar 24, 2012

Amen!   That's why I got MPPT... I knew that I would likely get the higher voltage panel and want to harness the otherwise discarded power.   <img src="/images/boards/smilies/smile.gif" border="0" align="absmiddle">

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