[RE-wrenches] Buck-Boost transformer to mitigate high voltage drop?

Tue Aug 16 10:59:30 PDT 2016

Chris:

If you do provide transformers I think they are called step-up/step down.
Buck/boost transformers I believe are to make adjustments to voltages.

I have learned that you need to account for the current flow and
direction.  For one-way flow, the upstream transformer has a slightly
different turns ratio than the downstream transformer to account for
voltage drop.  With two-way current flow, you might want to consult an
engineer (application or electrical) to determine the best, most efficient
transformer pair.  You can incur a lot of losses with transformers so
design is critical.

One other complication can occur:  In-rush currents can cause nuisance
beaker tripping.  You may need to buy a breaker with higher AIC rating to
compensate for this.

Also, I bought a transformer from a reputable manufacturer that had
mis-labeled terminals.  The smell was hard to forget.  I suggest you
ohm-out any transformer to identify terminals on the same and different
windings.

In general, this kind of project can have some unforeseen complications.  I
am not that experienced, but the experience I do have has come at some
cost.  I hope to help you and fellow wrenches avoid some of that pain.

Sincerely,

William Miller

[image: Gradient Cap_mini]
Lic 773985
millersolar.com <http://www.millersolar.com/>
805-438-5600

*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Chris Mason
*Sent:* Tuesday, August 16, 2016 10:39 AM
*To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
*Subject:* Re: [RE-wrenches] Buck-Boost transformer to mitigate high
voltage drop?

How much of the power produced will be self-consumed, how much will be
exported?

On Tue, Aug 16, 2016 at 12:16 PM, Howard Arey <scot.arey at solarcentex.com>
wrote:

Good day,

I have a potential client that has an existing 1,000 foot run from the
meter and transformer at the street to the home. This is 4/0 Al and quick
calcs show the voltage drop at over 12%. He acknowledges that the wire is
undersized to keep voltage at/about 240 volts (I have not measured directly
at the street / transformer yet).

I know the wire has the necessary ampacity to carry his current service
needs and to carry amps from the to-be-suggested solar system.

My concern is that the voltage drop will change the 240 volts at the
street/transformer/meter to 211ish (or will I see a higher 268’sh voltage
at the far house end?) at the house. The inverter will try to synch to this
voltage but of course this is outside of typical inverter parameters.

So, instead of re-running much large wire, does anybody have experience and
comments about potentially using a buck-boots transformer at the home to
get us back to 240 volts? This would need to be service entrance sized.

*Howard “Scot” Arey*

Owner, Solar CenTex

254-300-1228

scot.arey at solarcentex.com

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-- 

Chris Mason

NABCEP Certified Solar PV Installer™

Solar Design Engineer

Generac Generators Industrial technician

www.cometsolar.com <http://www.cometenergysystems.com>

264.235.5670

869.662.5670

Skype: netconcepts
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