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Building Reserve and Using KWH

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  • bcroe
    replied
    The PoCo bill came, I looked over the first 2 months of this net metering period. 2 years ago I was not
    running the 5 mini split heat pumps. By subtracting reserve built up from inverter generation, I have a
    pretty good idea of my KWH consumption. Going back 2 years, the consumption for April-May was
    about 46.3 KWH a day. The past 2 months consumption was about 31.6 KWH a day. I am going to
    credit this 32% reduction in use to the increased efficiency of the mini-split heat pumps, over the other
    heaters. It would be even more, except an additional building is now being temp controlled.

    Had a brief issue 29 May, both inverters went off and were having trouble getting back in service. Half
    an hour later things were normal again, doing about 50% of capacity under some clouds. I guess there
    must have been some kind of line fault, later I noted it was about 120/240VAC even with the inverters
    pushing, think that has dropped a bit.

    Meanwhile the new AC feed trenching is inching along. With all the rocks, that
    term may be too optimistic. Millimeters? Bruce Roe

    Leave a comment:


  • bcroe
    replied
    Generally by 9am this time of year, a visit to the inverter shed reveals the twin 7.5KW
    solar systems are both saturated at full power. That even if a slight bit of cloud is
    present, with this arrangement. But a couple days ago one system was down some
    hundreds of watts from the other. I decided to wait a day for better sun, got the same result.

    OK, a quick walk around with the clamp on DC ammeter revealed, String 9 was putting
    out ZERO current. I actually had been a bit suspect of somewhat reduced output from
    S9 before winter, but tests had not revealed any fault. I went to the combiner and pulled
    the S9 fuse, S9 was delivering zero volts.

    At the array, some test points I had left in place revealed substantial S9 output available.
    Apparently the string was not connected to the combiner. More checking revealed this
    failed MC4 connection of the string return connection.

    String9rtn2.JPG


    Why is that a 3 way connection? This 2 sided array has strings facing East and strings
    facing West. To save wire an E and a W string share a common return, since they could
    not both deliver peak output at the same time. Even if they had, the return wire would
    not be overloaded. I decided to wait for dark for a simpler and safer repair job, an
    outdoor outlet on the end of this array would power a light.

    So what was to be learned from the 7 years of experience with several hundred MC4s?
    First my ability to compare the 2 systems at a glance had immediately demonstrated this
    serious fault.

    2nd the output difference between the saturated system and the faulted system showed
    that the total number of panels facing E (in this case) was about right. A properly
    operating system generated enough power to saturate the inverter, but not enough to
    mask the loss of any section.

    3rd my past warnings about MC4s were not excessive. Perhaps this one got a bit
    of weather exposure, and/or perhaps the seals were not moisture tight, and the
    heating/corroding daily cycle finally escalated and destroyed it. In the future all
    MC4s here will receive a dab of anti-oxidant compound as insurance.

    4th this will probably not be my last MC4 failure.

    Meanwhile, the weather is improving, and the project to trench 4/0 aluminum wire
    out to the inverters may start soon. Conduit coming out to a trench is near
    complete, and some dirt has already been moved. Bruce Roe

    Leave a comment:


  • bcroe
    replied
    Originally posted by Mike90250 View Post
    Wow, that's just awesome Bruce, Thanks for all your documentation and information.
    It is not as awesome as being off grid, but I am way too lazy for that. Bruce

    Leave a comment:


  • Mike90250
    replied
    Wow, that's just awesome Bruce, Thanks for all your documentation and information.

    Leave a comment:


  • bcroe
    replied
    With net metering resetting my reserve KWH to zero at the end of March, the challenge is
    to get through April generating more KWH than used, so I do not need to buy any. To add
    more challenge, this is my first April with 5 heat pumps on line keeping 2 buildings comfy.

    Sat and Sun each generated 149 KWH, amazing in these parts. That requires the 15 KW
    plant to run flat out saturated some 9 hours and 48 minutes each day. That is only 8 KWH
    short of my best June day record. Not to worry, I am not only breaking even, but my
    spinning disc reserve meter shows more than 800 KWH reserve already built up. Those
    heat pumps are just so efficient. Bruce Roe

    Leave a comment:


  • bcroe
    replied
    Another solar year, the PoCo reset date was reached 30 March. I gave them my surplus of 4,240 KWH.
    That is a surplus of around 18% over usage. No propane heat was used in keeping 2 buildings in a
    very comfy temp range. The winter might be summarized as having relatively cold fall and spring, but
    relatively warmer winter. No resistive or propane backup heat was used, the heat pumps did it all. It is
    easy to imagine a much more severe winter using up all my energy reserve and more.

    The heat pumps have reduced to a NEW LOW, my labors and attention to managing energy. Things
    pretty much run themselves, with some snow removal required by me, just a part of the cleanup of drives
    and walkways here. Sort of like those Medallion Homes after the war, but I have even more stuff and do
    not pay for energy. A few problems not originally anticipated have been solved, some using technology
    not originally anticipated.

    Future improvements anticipated include recovering close to 800 KWH annually lost in transmission
    between buildings, by burying much larger aluminum wire. The prep work is in place at both
    ends, on site are the 24 inch deep trencher, and the 300 lb of wire on this cart to avoid much manhandling.

    RelCrt1Ma20.JPG

    Also possibly install an electric water heater, with a propane unit remaining as power outage
    backup. 5 rooms are prewired to get ceiling fans, or at least high efficiency overheat lighting.

    I am waiting to see if a certain tree is dead, before making a final revision of best array placement.
    Foundations can be worked on half the year, above ground stuff longer. This is not high priority,
    but each section completed will give an incremental decrease in snow removal efforts and some
    additional energy. In one case I just drove the snow blower by the newest array with
    blown snow hitting the top, and the little snow just fell off without manual effort.

    I am thinking of no longer making daily performance log entries, perhaps
    just record about the time of the monthly meter reading by the PoCo.

    Bruce Roe
    Last edited by bcroe; 04-10-2020, 12:06 PM.

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  • Ampster
    replied
    Thanks for the updates and demonstrating that we can all have different goals. The important issue is to have a well though out process to accomplish our goals.

    Leave a comment:


  • bcroe
    replied
    First time this winter the temp got down to minus 10F. The 4 heat pumps managed to keep
    the house in the 70s without any action from me. The out building (1 big heat pump) also
    managed to stay 55 degrees warmer than outside. The next big test is - 20F. Bruce Roe

    Leave a comment:


  • bcroe
    replied
    Overnight was a serious test of the car shop heat pump. With an output of up to 24,000 btu
    it has been set for 60F in the 1080 sq ft, modestly insulated building. This had been
    maintained in warmer weather. With 3F this morning the interior was 53F, so a 50F differential
    may be maintainable. It may do less well if we see Neg 25F outside, the pump effective
    limit, but any of these are way better than no heat. A propane furnace stands by to make
    up the difference if ever needed, but has not been used this winter. Bruce Roe
    Last edited by bcroe; 01-19-2020, 10:28 PM.

    Leave a comment:


  • bcroe
    replied
    With favorable weather (no snow), the adventure continues to install a heavy wire run out to
    the shed with the inverters. Already running out there Is a triple 4 ga, a phone style cable, a
    water line, and a cat 5E to the tower. So lets find existing cables with a cable tracer/wire
    locator and mark them with flags. Have a Tempo 508S and a Kolsol F02 which seem to have
    identical specs at 447KHZ. The former Ebay cripple had a bad transmitter, and the latter new
    unit had a bad receiver. I got results with the 508 receiver and the F02 transmitter.

    The breakers at both ends of the 4 ga were opened, and the tracer signal applied to one
    end of a de-enerized 240V wire. Return was to electrical box ground.

    Seems like you cannot have too many flags. Red is my 4 ga pwr, a couple feet down. Also
    detected, white flags, is my Cat 5E from the dish on my tower, barely below the surface. Not
    detected farther west, are the phone cables I buried in 2004 and a water line. I do believe I
    can detect a slight depression running along the ground from the original 4 ga trench. Think
    that sudden jog is a big rock?

    The plan is, start by trying to get a trench under a huge root for a big tree without actually
    cutting it, go from there to house wall. Unroll 4/0 triplex cable under the root and into the
    house, then work the other way to the shed. The current cat 5E will try to lift up and work
    under it, will also lay a new one half way down to the 4/0. Measure exact distance from
    buildings for future reference.

    I do have another tracer that operates at 125KHZ. Completely different ant, will see if it is
    useful in this situation. Need to build some kind of dolly for that very heavy reel of 4/0 triplex.

    Bruce Roe

    Cable6Jan1.JPG

    Cable6Jan3.JPG
    Last edited by bcroe; 01-07-2020, 10:26 PM.

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  • bcroe
    replied
    Originally posted by SunEagle
    They make "buried cable locators" that will send a signal down a buried cable that can be "sensed"
    by a receiver and avoided. Maybe you can rent one.
    Yes I have a couple different ones, but so far have not been able to follow the signal. I
    might set up lights for night operation, open all breakers at both ends of the run, and
    see if that helps. Bruce

    Leave a comment:


  • SunEagle
    replied
    Originally posted by bcroe View Post
    I believe another challenge for the direct burial heavy feed has been solved.
    The digger on my 18 inch deep trencher has been lengthened enough to
    reach 24 inches. Will not push it too hard.

    I still need to locate the original buried power cable, to avoid hitting it. Bruce Roe

    trencher243.JPGtrencher245.JPG
    They make "buried cable locators" that will send a signal down a buried cable that can be "sensed" by a receiver and avoided. Maybe you can rent one.

    Leave a comment:


  • bcroe
    replied
    I believe another challenge for the direct burial heavy feed has been solved.
    The digger on my 18 inch deep trencher has been lengthened enough to
    reach 24 inches. Will not push it too hard.

    I still need to locate the original buried power cable, to avoid hitting it. Bruce Roe

    trencher243.JPGtrencher245.JPG

    Leave a comment:


  • bcroe
    replied
    Originally posted by bcroe View Post
    The aluminum direct burial wire arrived, 288 lb for 300 foot Triplex. Looks like
    most of the connections can go straight into my box terminals, 2 of the 6 will
    need to be reduced to 2 gauge copper to go into a 100A breaker.
    Think I solved the transition of 4/0 AL to 1/0 CU house end of my triplex AL
    buried cable. These terminals are designed for AL or CU 200A circuit, mounted
    on half inch bakelite. They came from my 200A meter boxes, in the center to
    splice the neutral wires together. I removed them (as many probably do)
    because that wire runs straight thru, no connection. No bucks spent. The
    house end distribution box already has a suitable N terminal for that wire.

    Here the 1/0 is already wired to the (4 position) 100A breaker, 4/0 AL will come in
    on the right. Until the project completes next spring, the 80A breaker just above
    will continue to feed through adequate but less efficient 4 gauge.

    Oh I discovered a RANDOM blower operation mode for my electronic
    thermostat. I still would not use it, my unit is not random, can set and modified
    times as I decide

    Bruce Roe

    4010trans.JPG4010cover.JPG
    Last edited by bcroe; 10-05-2019, 12:44 PM.

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  • Ampster
    replied
    That was a simple solution for the inverter side. It also reduced the number of connections.

    Leave a comment:

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