No.
I am suggesting a 24vdc or 48vdc battery bank to store the power from the
panels. With panels like I have 24v bank requires parallel connection. 48v
requires two series panels then connecting parallel to produce almost 100v.
The bigger voltage difference helps the panels produce in other than optimum
conditions. The buck DC to DC converters in MPPT controllers worth their salt
change the voltage with only a small loss in watts. controllers that are of
the PWM variety just throw away the wattage created from the panel over the
bank voltage. Don't get any of the PWM controllers only the MPPT controllers.
I am suggesting an inverter to convert the bank voltage to the 120/220 vac. if
the controller requires vdc use a rectifier bridge, better yet a bridge using
fets to avoid loosing as much as one looses with diodes. Then filtering the
output with large capacitors.
If your capacitors are large enough they can supply the starting current of
the motor. I know soft start will not require large capacitors but why not use
them anyhow. Seems there are white papers listing large losses if the input
into the controllers for motors is not smooth. This is due to the power
required to produce the harmonic frequency.
As an added bonus I will give you more thought. Grid tie micro inverters could
be used on the panels. These MPPT controllers convert the panel power to the
line voltage of 220 ac typically. The source of the sine wave can be supplied
from a true sine inverter of small size. In my search I found such micro
inverters for around 100us each. The output is dependent upon a sine wave. You
have expressed that you want the voltage from the panels low. I agree with
you. The use of these micro inverters would defeat the original design plan.
I have not engineered a solution as described using micro inverters because
the system did not fit my needs, so you will have to do the job. What you need
to remember is special care will be needed with high voltage like 220. any
terminals exposed in any way while under way could end your life. I have been
thrown into a hot engine by a wake from a passing coastie. DC will not release
you the way AC will, you could be stuck to the thing until the power was
drained. Adding the danger that someone thinking they could knock you free may
join you. This is one reason I like the idea of lower voltage battery banks.
If you have problems with the high voltage capacitors you can just call for a
tow. The capacitors are much less likely to fail than a battery is, and it
serves nothing to reconfigure under way. Further a switch hooked up to a
resistor can discharge the capacitors before you work on them.
I hope I answered most of the questions you may have had. If not keep asking.
Kevin
On Monday, November 03, 2014 07:09:30 PM you wrote:
> Do you suggest using some sort of a solar 12/24Vdc to 120/230Vac inverter
> to power a 120V battery charger?
> The battery charger needs to be a variable power type, since input current
> will vary according to the sun conditions - and I dont know if such
> exists...(?)
> The motor controller for the 120V, 3 phace motor needs a input of between
> 110-350Vdc
Posted by: Kevin Pemberton <pembertonkevin@gmail.com>
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a New Topic | • | Messages in this topic (21) |
No comments:
Post a Comment