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Solar MPPT Charger & Lighting Controller Our new Solar MPPT Charger/Lighting Controller uses solar panels to charge a 12V or 24V battery and then works with LDR/ PIR sensors to run 12V DC lighting or an inverter. Last month, we gave the circuit details; this month, we show you how to build it and describe the setting-up procedure. Pt.2: By JOHN CLARKE T HIS UNIT is easy to build, with all parts mounted on a PCB coded 16101161 and measuring 141 x 112mm. This is mounted in a diecast case measuring 171 x 121 x 55mm. The PCB is secured to integral mounting points inside the case and is shaped so that it fits neatly around the central pillars on either side. As well as providing a rugged assembly, the diecast case also provides heatsinking for diodes D1 & D2, power Mosfet Q1 and power transistor Q3. 60  Silicon Chip Fig.7 shows the parts layout on the PCB. Begin the assembly by installing the resistors. Table 1 shows the resistor colour codes but you should also use a DMM to check each value as it is installed, as the colours can sometimes be hard to decipher. Note that the “in brackets” values shown for some of the resistors are for the 24V version of the Solar Charge & Lighting Controller. Note also that the 0.01Ω 3W resistor (just above fuse F1) should be left out at this stage of the assembly. It goes in after the fuse clips have been installed (see below). Diode D3 can go in next, followed by zener diodes ZD1, ZD2 & ZD3. These must all be mounted with the correct orientation, as shown on Fig.7. Leave power diodes D1 and D2 out for the time being. Zener diode ZD4 is not normally installed and a wire link is used for resistor R2. This is the standard set-up if using a PIR sensor that can handle a supply of up to 14.4V. siliconchip.com.au 100k IC2 LM358 4.7k 22k 100Ω 1 ZD4 12V 1W 100nF 100nF (Values in brackets (47k ) are for 24V version) (1k ) Conversely, ZD4 must be installed if you are using a PIR sensor that’s rated at 12V maximum. If ZD4 is fitted, you must also use a resistor for R2 instead of a link. Use a 270Ω resistor for a 12V battery and a 1.2kΩ resistor for the 24V version. In particular, note that ZD4 and a 1.2kΩ resistor (for R2) must be used for the 24V version, unless the PIR can operate directly from a 28.8V supply. IC1’s socket can now go in, followed by IC2, REG1 & OPTO1 which can all be directly soldered to the PCB. Check that these parts are all correctly orientated before soldering their pins. Trimpots VR1-VR5 can then be installed. VR1 & VR2 are 20kΩ types and may be marked as 203. VR3 & VR4 are 10kΩ trimpots (103), while VR5 is a 500kΩ trimpot (504). Once the trimpots are in, fit PC stakes to test points TP1-TP4 & TP­ GND, then fit PC stakes to terminate the leads from inductor L1. That done, install switch S1 and the 3-way pin headers for JP1 & JP2. Transistors Q2 & Q5 are next on the list. Make sure that Q2 is a BC337 and that Q5 is a 2N7000. Mosfet Q4 can then be installed; it’s mounted horisiliconchip.com.au 10 µF 35V 100k R1 100k 100nF Solar Lighting 100Ω VR1 20k LDR Light Threshold NTC PIR 470Ω 4N28 OPTO1 TP4 Timer mV/ C THERMISTOR 100nF 1 1k 68k (51k ) TP3 A Fig.7: follow this parts layout diagram to assemble the PCB. Power devices D1, D2, Q1 & Q3 must all be mounted on 10mm lead lengths, while LED1 is mounted on 20mm lead lengths so that it can later be bent over to protrude through the side of the case. Refer to the text for the winding details for inductor L1. DAY NIGHT LDR VR2 20k 10k 8.2k 22k 1 LED1 10k CON2 470pF ZD2 30V 1W 1.5k SWITCH R2 * * see text S1 2.2k 2.2k 100nF PIR TRIGGER SUPPLY – TP2 Q4 IRF1405N TPGND VR4 10k 4.7k 16110161 SET 5V <at>TP1 TP1 VR3 10k 10Ω SET BATT. + 1 JP2 – 330Ω VR5 500k LAMP Note: Lamp supply =battery voltage + 10nF ZD1 30V 1W 10nF – C 2016 16101161 Q2 BC337 JP1 M205 F1 10A CON1 BATTERY + Rev.0 D3 4148 2 x 100nF X2 Class 470Ω 0.01Ω 100 µF – ZD3 18V 1W L1 5 µH (10 µH) REG1 TL499A SOLAR PANEL 2200 µF/25V (Values in brackets (470 µF/63 V) are for 24V version) IC1 PIC16F88 + 10Ω 2200 µF/25V (470 µF/63 V) TIP31C 1k 1W Q3 Q1SUP53P06-20 100Ω + + D1 MBR20100CT D2 MBR20100CT 1nF CON3 10Ω 100nF zontally on a small finned heatsink with its leads bent down through 90° so that they go through their respective holes in the PCB. Be sure to secure the assembly in place using an M3 x 6mm machine screw, washer and nut before soldering the leads. There is no need to electrically isolate Q4’s tab from the heatsink, so an insulation washer is not required. Now for the fuse clips. These must go in with their retaining tabs on the outside, otherwise you will not be able to fit the fuse correctly later on. Once these are in, install the 0.01Ω 3W resistor. The next step is to fit all the capacitors. Be sure to orientate the electrolytic types correctly. Note that the values and voltage ratings of the two large electrolytic capacitors at top left depend on whether the unit is built for 12V or 24V operation. Follow with screw terminal blocks CON1-CON3. Note that CON1 uses large screw terminals in order to handle the heavy current requirements for the solar panel, battery and lamp connections. CON2 and CON3 are smaller units and are made up by dovetailing separate connectors together. In Q5 2N7000 INSULATING WASHER INSULATING BUSH M3 x 10mm SCREW M3 NUT TO220 DEVICE BOX SIDE PC BOARD Fig.8: power devices D1, D2, Q1 & Q3 must be electrically isolated from the case using insulating washers and insulating bushes. After mounting each device, use your DMM (set to a high Ohms range) to check that the metal tab is indeed isolated from the case. particular, CON2 uses a 3-way and 2-way connector, while CON3 uses two 2-way connectors. Make sure that CON2 and CON3 are orientated with their openings towards the outside edge of the PCB. Power devices Power devices D1, D2, Q1 and Q3 are all installed with their mountMarch 2016  61 Inductor L1 is made by twisting six 416mm-long strands of 0.5mm copper wire together and then winding on seven (or 10) turns – see text. The ext­ernal leads are fed into the case via cable glands. Additional cable glands will be required for the optional lamp, PIR and external switch connections. ing tab holes about 22mm above the PCB. In practice, this means mounting the devices on 10mm lead-lengths and that’s best done with the aid of a 10mm-wide cardboard spacer slid between the device leads. Be careful not to get these devices mixed up and note that the metal tabs go towards the outside edge of the board. LED1 (centre, right) must be mounted so that it can later protrude through a hole in the side of the diecast case. It’s just a matter of soldering it in at full lead length, then bending its leads over at right angles about 8mm above the PCB (eg, by bending it over a 8mm cardboard spacer). Be sure to orientate the LED correctly; its anode (A) lead is the longer of the two. Winding inductor L1 Inductor L1 is wound using six strands of 0.5mm enamelled copper wire that are all twisted together. Begin by cutting 6 x 416mm lengths of wire, then strip about 15mm of enamel off each wire at one end. Lightly tin these wire ends, then twist the ends together and solder them. Next, secure this soldered end in the chuck of a hand or battery-powered drill and twist all the wires together, so that each wire twists by 360° ap- proximately every 20mm (see photos). That done, wind seven turns (or 10 turns for the 24V version) through the toroid, spacing the turns evenly. Once they’re on, position the inductor on the PCB and bend the soldered end so that it mates with one of the inductor’s PC stakes. The other end can then be positioned to mate with its PC stake and cut to length. Finally, strip back the enamel from the leads at this end, twist and solder them together and install the inductor on the PCB. A couple of cable ties fed through adjacent holes on either side of the inductor are then used to secure it in place. Note that multiple strands of wire are used to minimise the impact of skin effect. If a single, larger wire had been used instead, its effective resistance at the switching frequency would be higher, leading to greater losses and more heating. The approach taken here to reduce Table 1: Resistor Colour Codes (12V Version) o o o o o o o o o o o o o o o o No.   3   1   2   2   1   2   2   1   2   2   1   1 (opt.)   3   3   1 62  Silicon Chip Value 100kΩ 68kΩ 22kΩ 10kΩ 8.2kΩ 4.7kΩ 2.2kΩ 1.5kΩ 1kΩ 470Ω 330Ω 270Ω 100Ω 10Ω 0.01Ω 4-Band Code (1%) brown black yellow brown blue grey orange brown red red orange brown brown black orange brown grey red red brown yellow violet red brown red red red brown brown green red brown brown black red brown yellow violet brown brown orange orange brown brown red violet brown brown brown black brown brown brown black black brown not applicable 5-Band Code (1%) brown black black orange brown blue grey black red brown red red black red brown brown black black red brown grey red black brown brown yellow violet black brown brown red red black brown brown brown green black brown brown brown black black brown brown yellow violet black black brown orange orange black black brown red violet black black brown brown black black black brown brown black black gold brown not applicable siliconchip.com.au Using The Solar Charger/Lighting Controller With 24V Batteries As stated last month, the Solar MPPT Charger/Lighting Controller can also be used with 24V batteries and 24V solar panels. However, this requires some component changes to the circuit and these are indicated in brackets on Fig.7. In summary, the required changes are as follows: (1) The 22kΩ resistor at pin 3 of lC2a is changed to 47kΩ, the 100Ω resistor feeding ZD2 is changed to 1kΩ and the 22kΩ resistor at the AN2 input of IC1 is changed to 51kΩ. (2) The 2200μF 25V low-ESR capacitors are changed to 470μF 63V low-ESR types. (3) The number of turns on inductor L1 is increased from seven to 10. (4) If used, R2 should be increased to 1.2kΩ. Several set-up changes are also required: (1) The voltage at TP2 (set by VR2) must now be the battery voltage x 0.15625 (instead of 0.3125). (2) The voltage set at TP3 for temperature compensation (step 8 in the setting up procedure) must be half that set for 12V operation. For example, for 38mV/°C compensation with a 24V battery, TP2 should read 1.9V (not 3.8V). skin effect is similar to that of using Litz wire, except that the twisted wires are larger. That completes the PCB assembly. The next step is to prepare the case. Case drilling The first step here is to drill two holes in one side of the case to accept two IP68 8mm cable glands, plus another hole in the opposite side for a 6.5mm cable gland. To do that, position the PCB inside the case and carefully mark out the positions for these cable glands. As shown in the photos, they are positioned opposite CON1 and CON3 and are centred vertically. The PCB can then be removed from the case and the holes drilled and reamed to size. Deburr all edges with a small round file. That done, the PCB can be temporarily repositioned in the case and the mounting holes for the four power devices (D1, D2, Q1 & Q3) and for LED1 marked out. Drill these holes to 3mm, then use an oversize drill to remove any metal swarf so that the area around each hole is perfectly smooth. This latter step is necessary to prevent punch-though of the insulating washers used with the power devices. The PCB can now be secured inside the case using the supplied screws and the four TO-220 power devices attached to one side of the case, as shown in Fig.8. Note that it is necessary to isolate each device tab from the siliconchip.com.au Table 2: Capacitor Codes Value 100nF 10nF 1nF 470pF µF Value IEC Code EIA Code 0.1µF 100n 104 0.01µF   10n 103 0.001µF    1n 102   NA 470p 471 case using an insulating washer and insulating bush. Once they have been installed, use a digital multimeter (set to read ohms) to confirm that the metal tabs are indeed isolated from the metal case. If a low resistance reading is found, check that the silicone washer for that particular TO-220 device has not been punctured by metal swarf. If it has, then clear away the swarf and replace the insulating washer. Setting up The step-by-step setting-up procedure is as follows: Step 1: check that IC1 is out of its socket, then fit the fuse and apply 12V to the battery input terminals. Step 2: connect a DMM between TP1 and TPGND and adjust VR1 for a reading of 5.0V. Step 3: disconnect the 12V supply and wait for the 5V rail (measured at TP1) to drop to near 0V. Step 4: plug IC1 into its socket, then reconnect the 12V supply. Step 5: measure the voltage across the Miss this one? Big, bold and beautiful – and simply the BEST DIY loudspeaker system ever published . . . anywhere! Published in May, 2014 The Majestic Everything about this superb loudspeaker system is impressive: size, physical presence, power handling, efficiency – and most of all, performance. Compare them with commercial loudspeakers ten and twenty times the price! If you want the ultimate build-it-yourself loudspeakers, you want The Majestic! You’ll find the construction details at siliconchip.com.au/Project/Majestic Crossover PCB available from On-Line Shop INTO RADIO? How about SiDRADIO? Take a Cheap DTV Dongle and end up with a 100kHz2GHz SoftwareDefined Radio! Published October 2013 It’sDon’t yours with the 200W pay $$$$ for a commercial Ultra LD Amplifier from receiver: this uses a <$20 USB DTV/DAB+ dongle as the basis for a very high performance SSB, FM, CW, AM etc radio that tunes from DC to daylight! Features:  Tuned RF front end  Up-converter inbuilt  Powered from PC via USB cable  Single PCB construction Lots of follow-up articles, too! Want to know more? Search for “sidradio” at siliconchip.com.au/project/sidradio PCBs & Micros available from On-Line Shop March 2016  63 Lighting & Inverter Options As stated last month, jumpers JP1 & JP2 select the various lighting options. Here are a few suggestions: (1) Night-time garden lighting: the light sensor allows the lights to switch on at dusk and they can remain lit for a preset period of up to eight hours, as set by the timer. Alternatively, you may wish to have the lights lit for the entire night and to switch off automatically at sunrise, provided there is sufficient battery capacity. (2) Security or pathway lighting: the lights can be set to switch on after dusk but only when someone approaches the area. In this case, a PIR movement detector switches on the lights while the timer switches off the lights after the time-out period, typically 1-3 minutes or longer (8-hour maximum). (3) Shed lighting: in this case, you may opt to switch the lights on and off using an external pushbutton switch. The lights can remain on until they are switched off again or they can switch automatically after a preset period, or at sunrise (as detected by an LDR). Normally, the controller would be set so that the lights only come on when it is dark. However, you might want the lights on during day in a shed and this can be done using the third option listed in Table 1 last month; ie, JP1 in the night position, JP2 in the LDR position and the LDR left disconnected. Using an inverter As mentioned last month, you can directly switch up to 10A of 12V DC lighting via the LAMP terminals on CON1. Alternatively, instead of using 12V lamps, you can use an inverter to run 230VAC lamps. This latter option requires the addi- Battery size CON2 PIR POWER + PIR SIGNAL PIR POWER 0V REMOTE SWITCH CONNECTION + – POWER N/O CONTACT SOLAR LIGHTING CONTROLLER PIR SENSOR Fig.9: here’s how to connect the Altronics S5134A PIR Sensor to the unit. Note the link between the negative supply terminal & one of the NO contacts. Mounting & Connecting A PIR Sensor An Altronics S5314A PIR sensor was used with our prototype unit but other similar PIR sensors will also be suitable. The Altronics sensor can be configured for either a normally open (NO) or normally closed (NC) output. In this case, it’s necessary to select the NO option using the supplied jumper. Once that’s done, the PIR sensor is connected to CON2 on the Solar Charge/ Lighting Controller as shown above in Fig.9. Note the link between the PIR’s negative power terminal and one of its NO contacts. The PIR’s other NO contact connects to the PIR signal input on CON2. In operation, the signal input terminal is normally pulled to +5V via R1 (100kΩ) on the controller’s PCB. However, when movement is detected, the PIR’s contacts close and the signal input is pulled down to 0V, thus triggering the controller and turning on the lights. When mounting the PIR sensor, be sure to position it so that it covers the desired detection area. You can test its coverage by temporarily mounting it in position, connecting the 12V supply from CON2 and watching the detect LED in the PIR sensor light as you move around the detection area. 64  Silicon Chip tion of an external relay (rated at 12VDC 150A) to switch the inverter on and off. Fig.10 shows the details. As can be seen, the external relay’s coil is connected across the LAMP terminals of CON1, while its NO (normally open) contacts switch the positive supply line from the battery through to the inverter. The negative supply terminal in the inverter is directly connected to the negative battery terminal. A 150A relay is recommended to cope with the surge currents drawn by the inverter. If you are using a 24V battery, you will need to connect a 47Ω 10W resistor in series with the relay’s 12V coil. Assuming that the relay has a 50Ω coil, this 47Ω resistor will effectively halve the voltage that’s applied to the coil. Note that the supply wiring to the relay and to the inverter must be rated to carry the inverter’s current. A 12V 600W inverter, for example, will need supply wiring that’s capable of carrying at least 50A. A minimum battery capacity of 80Ah is recommended. A larger battery can be used provided that you don’t draw more out of the battery than the solar panels are able to top up. If you do use more power than the solar panels can provide, the battery will eventually be discharged. LiFePO4 charging As mentioned, when using a LiFePO4 battery terminals and multiply this by 0.3125. Step 6: press switch S1 and wait for a few seconds, then connect a DMM between TP2 and TPGND and adjust VR2 so that the DMM reads the calculated figure. For example, if the battery terminal voltage is 12.0V, TP2 should read 3.75V. Step 7: determine the recommended temperature compensation (in mV/°C) for your battery by looking up its specifications. Usually, there will be a graph which show the battery’s fully charged voltage against temperature. You will need to determine the mV/°C figure from this graph. Step 8: connect the DMM to TP3, hold down switch S1 and adjust VR3 until the meter shows the required temperature compensation value. This reading will be in the range of 0-5V, represiliconchip.com.au + D1 MBR20100CT + TO SOLAR PANEL – + SOLAR PANEL 2200 µF/25V (470 µF/63 V) – LAMP LAMP– M205 – Note: Lamp supply =battery voltage + – BATTERY + 100nF 87A R2 * * see text 87 85 150A 12V RELAY S1 ZD2 1.5k SWITCH 30 – CON2 PIR TRIGGER SUPPLY 86 F1 10A 2.2k LAMP+ + CON1 –BATTERY – BATTERY + 0.01Ω 100Ω +BATTERY 2.2k Fig.10: an external relay is required if you wish to power the lamps via a 230VAC inverter. Note that the wiring to the battery and to the inverter must be rated to carry the inverter’s maximum current. ZD4 12V 1W 100nF 100nF (Values in brackets are for 24V version) (1k ) + SOLAR LIGHTING CONTROLLER – (85 & 86 = COIL; 30 = COMMON; 87 = NO CONTACT) 230VAC INVERTER battery, the mV/°C setting using VR3 must be set to 0mV/°C. This allows the correct charging cycle for this battery chemistry. senting 0-50mV/°C; ie, 1V = 10mV/°C. Note that this applies to lead-acid batteries only. If you have a LiFePO4 battery, set VR3 fully anticlockwise for a 0V reading at TP3. Thermistor connection Thermistor TH1 can be directly connected to CON3 inside the case if you are not too concerned about temperature compensation. However, you would then be relying on the temperature within the case being similar to that of the battery. The odds are that the case and battery temperatures will be different, though. So, instead of mounting it in the case, the best way to mount the thermistor is to tape it to the side of the battery and connect it to CON3 using single-core shielded cable (fed in via the cable gland). This lead should siliconchip.com.au In addition, a cell balancer should be connected to the balance connector on the battery. This is necessary to ensure that each cell that makes up the battery is charged to the same level as the others. A suitable cell balancer is published elsewhere in this issue of SILICON CHIP. Cable Resistance Must Be Kept Low When the Solar Charge Controller is used with a 120W panel, the charging current to the battery can be as high as 10A. Hence, the cable resistance between the Charge Controller and the battery should be made as low as possible, otherwise voltage losses will affect the changeover from the bulk charge to the absorption stage of charging. This will reduce the overall charging efficacy. To minimise these voltage losses, mount the charger close to the battery and use heavy duty cables. For a total cable length of less than one metre (ie, total wire length for the positive and negative wires), cables with a cross-sectional area of 1.29mm2 (eg, 41 x 0.2mm) can be used. This will result in a voltage loss of just 100mV at 10A. For longer wire lengths, use heavier duty cable. For example, 8-gauge wire with 7 x 95/0.12mm wire and a cross sectional area of 7.5mm2 can be used with a total length of up to 5.5m. be soldered to the thermistor and the solder joints insulated with heatshrink tubing (polarity is unimportant). Note that you must have the thermistor connected if the mV/°C adjust- ment, as measured, at TP3 is above 0V. If it’s left out, LED1 will flash to give the disconnected thermistor indication and charging will not take place. Conversely, if VR3 is set to give 0V at March 2016  65 Table 3: Setting The Time-out Period TP4 Voltage Time-out Period (Approx.) Adjustment Steps Timeout Calculation (Approx.) 0-2.5V 2-250 seconds (approx. 4 minutes) 2 seconds 2.5-4.9V 4-480 minutes (up to 8 hours) 4 minutes TP4 voltage x 100 seconds (2 seconds miniumum) (TP4 voltage - 2.5V) x 200 minutes (4 minutes minimum) Above 4.9V No timeout TP3 (ie, 0mV/°C compensation), such as when using a LiFePO4 battery, the thermistor can be left disconnected. Connecting the LDR The LDR will need to be connected to CON3 if you want the lighting to be controlled by the ambient light level. You then have to set jumpers JP1 & JP2 to determine whether the lights come on at night or during the day – see Table 1 last month. As with the NTC thermistor, the LDR can be attached via a length of singlecore shielded cable (or use figure-8 lead). The LDR should be mounted in a location where it receives ambient light only; not light from the lamps being switched by the Solar Charge/ Lighting Controller. An external switch can also be used for lamp on/off control. This should be a momentary-contact pushbutton switch. This is connected to CON2’s switch terminals using figure-8 cable (ie, it connects in parallel with switch S1 on the PCB). Another option is to connect a PIR sensor to CON2 and use that to control the lamp switching. An accompa- Positioning The Solar Panel The solar panel should be mounted on a roof or in some other position where it has an unobstructed view of the sky. In Australia, NZ and other southern hemisphere locations, it should be set facing north (or south for northern hemisphere locations). The panel’s inclination should be roughly 23° up from horizontal for NSW, SA, central/south WA and the North Island of NZ. Slightly higher angles are required for Victoria, Tasmania and NZ’s South Island, while slightly lower angles will be needed for Qld, NT and northern WA. If in doubt, check the inclination required on internet sites. In addition, take care to avoid any possibility of shadowing (eg, from a pole or tree) as the sun traverses the sky. nying panel in this artricle describes how to do this. Setting the time-out period Depending on your application, the timer will need to be set to an appropriate period. The time-out period can be adjusted from two seconds (2s) up to about eight hours using VR4. Table 3 shows the time-out with respect to the voltage on TP4, as set by VR4. This adjustment must be made while S1 is pressed, with a multimeter connected between TP4 and TPGND. For voltages up to 2.5V, the timeout period in seconds is simply the measured voltage multiplied by 100. For example, a 1V setting will provide a time-out of 100 seconds. For TP4 voltages above 2.5V, it’s a bit more complicated. The procedure is as follows: divide the required timeout period in minutes by 200, then add 2.5V to this figure and adjust VR4 until the voltage at TP4 matches the calculated value. Note that the minimum time-out SC above 2.5V is four minutes. Are Your S ILICON C HIP Issues Getting Dog-Eared? Are your SILICON CHIP copies getting damaged or dog-eared just lying on a shelf? Can you quickly find a particular issue that you need to refer to? Keep your copies of SILICON CHIP safe, secure and always available with these handy binders REAL VALUE AT $16.95 * PLUS P & P Order now from www.siliconchip.com.au/Shop/4 or call (02) 9939 3295 and quote your credit card number. *See website for overseas prices. 66  Silicon Chip siliconchip.com.au