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Advice needed on adding a Wind Turbine (generator) to a DIY PV Solar System. Answered

I have bought a 12 volt FD-300 300 watt wind turbine to add to my 12 volt DIY solar setup. The solar setup consists of 3 home made 70 watt panels on a single axis tracker charging 6x 12 volt 85 ah batteries wired in parallel (510 ah total) through a 20 amp controller. I run a 12 volt fridge/freezer (120 liter) and my now 12 volt (was 240 volt) evaporative air cooler (cools our 3 bedroom house) off the controller load output. The wind turbine has an inbuilt regulator. The instructions for the wind turbine tell me to attach it's + and - wires directly to it's own dedicated terminals on the battery bank. This is of great concern to me. How can this be done when the batteries are already connected to each other and to my systems controller? If it can be done without damage to the batteries would I still run the appliances through the load output on my controller? Would the different charge limiters cause an issue? My controller cuts out at 13.7 volts while the turbines controller would want to allow a charge of 14.1 volts. The two controllers also have different lower limits. As you can see I'm confused and in desperate need of quality advice. Thank you for taking the time to read this.


Your solar panel system is actually a separate charger than the turban. If you have a charger for the solar system, you don't need a diode in line. The charger should have the blocking diode built in. Check the specs of the charger. The turbine will need a charger with a diversion feature of it's own in most cases. Again, check the specs of your turbine if it's 'store bought'. Some turbines have an auto sensor and shutoff built in. Some don't. If not: You'll need a controller to switch to 'diversion' once the batteries are fully charged because the turbine will continue to produce electricity after the batteries are charged and can damage your battery bank. Outback, Xantrex C series among others have this feature. The diversion load can be a 12 volt hot water element, light bulbs or a resistor mounted on a heat sink. Depending on the model of turbine you have, if it does'nt already have a blocking diode built in, you'll also need a blocking diode if the charger does'nt have one, when the wind stops, to keep the turbine from taking power from the batteries. The diode should be rated at twice the amperage and voltage that the turbine can produce. The turbine should also have it's own fuse box and emergency cutoff switch for saftey or for emergency shutdown. Hope this helped. Good luck..

You could always get a seperate controller and seperate batteries, and have an some kind of automatic switch that alternates between the battery banks...... Just a thought

connect it as if it's another pv panel. so your controller controls it too

basically it should be like parallel connection thru diode to the input bus of your controller. if you have an input resistor on the pv's then use separate resistor with the wind generator. this ensures the controller does not get satisfied with the voltage it gives and stops taking energy from the pv's

connecting it to its own independant battery may be more efficient due to the satisfaction effect

Thank you very much for your reply. The wind turbines onboard controller has it's own non return diode fitted as does the pv controller I am using. Would the two non return diodes conflict in any way? The instructions that came with the wind generator, fairly ordinary though they are. tell that running through an inline diode will cause malfunction of the onboard controller. Would the diode in the pv controller be considered an inline diode? Following the advice given in another online article I read I have not fitted diodes to the panels. Apparantly being a 12 volt system the diodes would potentially cause greater current loss to the batteries during the day than what would be lost back to the panels at night. On the same subject...... The recommended wire size to use over the distance I have between the wind generator and the battery bank is around 6mm. Does this have to be one 6mm cable or can I make up the wire diameter by using multiple runs of thinner wire (I have some 2mm 3 core house wire) without getting significant voltage drop? Thanks again. Rob.

if i understood right inline diode means diode connected in series with the wind turbine

most likely its cause the turbine conrol circuit powers itself from the battery. if thats the case maybe some hacking of its circuit or connecting it to a stepped battery (small battery and then diode and the real batteries) might work

if you connect it and the pv's in parallel to the battery then the diode on the pv's is not inline (the turbine sees only the battery anyway) but then you have even higher possibilities of satisfaction

do the pv's actually work without diode or you just wonder if ? i dont know if its good for the panels to get electricity instead of making it. it may be worse with the higher voltage from the wind turbine

you should have a fuse or breaker protection on the panels too. in case a panel goes short circuit the battery may output very high current that'll damage panels / resistors / etc (and may be a fire hazard)

to disconnect the panels at night you may try a fet (it may have way lower losses than transistor) or mechanical thermal relay that switches on or off depending on the sun that heats its contacts (cons are some wasted sunlight in the morning)

The pv's are currently each supplying 4 amps at around 16 volts (up to 19 volts when it's cool like in the morning) to the battery bank. I'm assuming the diode in the controller prevents power being fed back to the panels. Thank you. I will fit a fuse to each of the panels. Would a 10 amp fuse be adequate or would you recommend something else? Thank you. Rob.

it may be a bit too large but is ok

less amp is better but too less amp may ocassionally blow without reason

a fuse has voltage drop just like a diode but smaller. the drop is lower when fuse amps are higher

i'd prefer a fast magnetic 6 A breaker (one that trips imediately if current > 6 A) or something similar. 6 A is fairly above 4 A and you dont have to change fuse if it tripped (which may sometimes happen)

a diode prevents power from doing that. but if its efficiency does not satisfy you (0.7 V @ 4A = 2.8 W wasted energy per panel) you can try a fet instead

if the pv voltage drops cause they heat in the sun you can add heatsink (made of aluminium window frame etc) to the back of the pv's. blowing wind in it cools them down