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y Philippines Retirement Solar Off Grid System
solarnewbee:
Thanks for the info TinyT,
I have a step down transformer I use for HVAC that steps down from 120, 208 or 240 to 24v. I have tried many configurations but get the same results. Any ideas where to head from here? You were definitely right about the voltage, as soon as I added caps the voltage jumped to from 122vac to 165vac.
Thanks
tinyt:
See attached picture.
solarnewbee:
Got it down to 146! The charger although doesn't seem to like that.
Would a high wattage 100r get it down to comfortable levels?, say around 125?
The 145v is the PV open circuit volts. PV array MPPT voltage range is 32-130v, so I will need to go lower.
maybe a voltage divider with 100w resistors. 22k x 3.9k = 124.015.
Watcha think?
tinyt:
It might work. But maybe shoot for 130vdc (92vac) so change the 3.9k to 6.8k. You might need a fan to cool down the resistors.
solarnewbee:
Hey tinyt,
Seems 100w 22k and many other values are not popular. I’m going for 6.9k x 6.9k for 73v. Since I’m using 36v 300w panels I am series them for 72v. I have a blown power supply that I put the high voltage dc supply in and it has a heat sink and fan. I had to put a 2 meg resistor across to drain the caps so I don’t get a bite. Got a screwdriver stuck to the leads taking a short cut ;D. If the system can’t keep up then maybe triple up for 108v. For now I’ve got 2 marine batteries and 2 1500w space heaters for testing.
Are you familiar with PJ inverters. My15kw has 2 power boards and one control board. Each has 2 smaller heat sinks with fets that are on the coil side and a large heat sink that the positive is connected to. If you had to label these, what would you label them. I have ds18b20 temp sensors on each heat sink that show on a dashboard to monitor temps and control the fan. I know Oz covered this somewhere and that thread is very long. Coil has one too.
Cheers!
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