Building Reserve and Using KWH

[J.P.M.]

This area usually dodges most of that, but we
did get hit with -10F temps and wind giving a chill of -30F (how much
of that applies to buildings?).
Bruce Roe

Bruce:

Strictly speaking, since wind chill is defined as what the air temp. feels like to exposed human skin, not much, that is, zero.

However, dwelling heat loss (or gain) is affected by dry bulb temp. difference inside to outside a dwelling and wind velocity as well as solar input and the radiant effects of the surroundings (including the effective sky temp.)
The higher the wind velocity is on a building element (with effects for wind direction relative to the building element under consideration thrown in), the greater the heat transfer component due to wind vector will be.

I believe I understand the physiological concepts involved with the concept of wind chill, but I always thought wind chill was mostly a bunch of B.S. hype whose only use was/is to make people feel more catastrophic.

If I was out shoveling my driveway in Buffalo w/10F. air temp. and 30 MPH wind (which was pretty common), about the only parts of my body exposed to the air was my nose and eyes. Kind of like who in their right mind opens a window in a blizzard, who's out running around outside butt naked in the cold anyway ?

Give me the dry bulb temp. and the wind vector and I'll dress appropriately for the circumstances.

[bcroe]

So another year, Nyle periodically says the unit will
be available, but once again failed to deliver it. Bruce Roe

Once again Nyle announced the e8 water heating heat pump adapter,
might soon be available. It is still in the process of being Energy Star
certified, UEF tested, UL tested, and other things. If I ever get one,
the energy reserve might be exhausted, better than giving it away.

Although this property was purchased with an eye to eliminating the
building maintenance (painting, etc), there was one standard roof on
the house. The shingles, facia, and rain gutters got replaced in 2021,
but now it was so slippery I could hardly go up there. As discussed
earlier, clamps to attach are quite expensive, $5 and up each. After
a bit of experimentation, I came up with this DIY version, using the
same 6061 aluminum and 18-8 hardware as the ground mounts. I
put some special conductive tape over the roof ridge first, to avoid
scratching the paint too much.

This is not normally under much stress, it just gives me a handhold
and a place to connect a safety strap. Note the foot friction strips
which stick to the roof. Bruce Roe

IMGP2436.jpg

[DanS26]

hey Bruce...just wondering how those 7.5 Fronius inverters are holding up?

I wake up every morning and think I'm glad to see another day. My eleven year old Fronius transformer inverters must think the same thing........well maybe if they were AI.

[bcroe]

The pair of Fronius IG 7.5 are just doing their thing after 10 years.
The new-out-of-the-box spare is mounted next to them, just need
to move 2 wires and throw a breaker if backup is needed. Guess
it might be a good idea to actually try that some day, might take
commissioning to get it going. No more worries about high line
voltage programming since the heavy feed was installed in 2020.

Looking good so far this year, the 15KW inverter plant delivered
150KWh today. The previous year was rather poor sun, generation
was a bit under 28,000 KWh. I got to keep more of that, the 2020
heavy feed is delivering close to an extra 1000KWh of generation
to the meter for credit. I made it past 1 April reset with a 1700 KWh
in the black surplus (given to the PoCo). Most stuff here just ran,
one of the 6 heat pumps needs attention.

Some energy ideas, new mounts could boost output and reduce snow
accumulation. And more house insulation, windows and in attic.
Observation of loads is ongoing, but Energy Star and some mods
have brought efficiency to a high level. Design a clipping level monitor.

However most attention today is catch up on stuff ignored for the
first PV decade. Need to get a new antenna up before the old one
falls down, still considering J.P.M.s advice how to (not) do that on
the steel roof. Some really big chunks of snow slid down this winter,
I am building some clamp on slide restrictors using the same 6061
aluminum and 18-8 SS bolts that have worked so well holding panels.
Bruce Roe

[DanS26]

I recently added an antenna to my mid-1800's barn with a very slick metal roof.........

IMG-0756.jpg

[bcroe]

Here I am again, smoke from wild fires in the NW is sending haze over
the IL area again. While not terribly severe, it is enough to cause the
inverters to drop out of clipping (about 7600W each), to more like 7300
or 7400W. Bruce Roe

[bcroe]

After a decade the 15KW system here has again developed
wiring problems. The twin 7.5KW inverters normally are a
match to around 1%, but lately EAST was lagging some. A
quick check with the clamp on DC ammeter indicated all
strings were close to a match. More checking, after half a
day running full power (that is up to 8 hours with this
configuration) the EAST DC disconnect box was getting pretty
warm.

As usual I set up a night work light and waited for the darkness.
Inside the Square D 361 box a 6 gauge wire looked like it
was cooking its insulation. The 361 is rated 30A against
the 22 I run, and 600VDC against my 400, 3 contact positions.
Something about the plus array wire was making poor contact
and getting ready to burn out. It was not my wire clamp screw.

I had this same failure on another contact years ago, I had
just moved the wires to the spare position. Something was
not making good contact, not sure if it was the bolts holding
metal together, or the switch contact. Is there a contact lube
that should be used on these?

Fortunately I have a lot of spare parts, and these boxes are
designed so a few screws from the open door side allow
replacing whole units. I found a nice switch section, made
sure all its screws were pretty tight, and soon had it installed.
Hand test today indicated proper cool operation.

There are plenty of the 361 outdoor boxes on Evil Bay, some
with 600V fuses (that I do not need), and some with just a
switch. Bruce Roe PVburnedDC.jpg

[Mike 134]

After a decade the 15KW system here has again developed
wiring problems. The twin 7.5KW inverters normally are a
match to around 1%, but lately EAST was lagging some. A
quick check with the clamp on DC ammeter indicated all
strings were close to a match. More checking, after half a
day running full power (that is up to 8 hours with this
configuration) the EAST DC disconnect box was getting pretty
warm.

As usual I set up a night work light and waited for the darkness.
Inside the Square D 361 box a 6 gauge wire looked like it
was cooking its insulation. The 361 is rated 30A against
the 22 I run, and 600VDC against my 400, 3 contact positions.
Something about the plus array wire was making poor contact
and getting ready to burn out. It was not my wire clamp screw.

I had this same failure on another contact years ago, I had
just moved the wires to the spare position. Something was
not making good contact, not sure if it was the bolts holding
metal together, or the switch contact. Is there a contact lube
that should be used on these?

Fortunately I have a lot of spare parts, and these boxes are
designed so a few screws from the open door side allow
replacing whole units. I found a nice switch section, made
sure all its screws were pretty tight, and soon had it installed.
Hand test today indicated proper cool operation.

There are plenty of the 361 outdoor boxes on Evil Bay, some
with 600V fuses (that I do not need), and some with just a
switch. Bruce Roe PVburnedDC.jpg

Is that brownish color light rust on the rivets? Perhaps some condensation over the past 10 years leading to the poor connection.

[DanS26]

Bruce, I use silver conductive grease on every connection and a torque screwdriver or wrench. Not to be confused with dielectric grease. It’s expensive but we’ll worth it IMO. Use very sparingly as excess will short a circuit. If + and - are near each other.

Never had a connection failure in my system.

[bcroe]

Bruce, I use silver conductive grease on every connection and a torque screwdriver or wrench. Not to be confused with dielectric grease. It’s expensive but we’ll worth it IMO. Use very sparingly as excess will short a circuit. If + and - are near each other.
Never had a connection failure in my system.

I am again bringing the main PV wiring into a more regular review,
even using a temp gauge to check for a box heating up after a
few hours at max power. I will be using some kind of terminal
protection on everything now. And spare shutdown assemblies
are prepared and sealed, just in case. The post mortum hints to
me, the issue has been the aluminum terminal block that came
bolted to the DC shutdown switch assembly. I am replacing all
of these with copper terminal blocks + anti corrosion stuff.

This year the big solar item is the smoke. Usually not so common
here in nothern IL. Even smoke not looking so thick, has a big
impact on solar energy. I am used to seeing the 15KW system
peaked out for nearly 8 hours a day many times. But recently it
has trouble getting up to the full 15KW capacity. Even when the
sky is not cloudy, production might be down 20% or more. Still
the array is fighting it, energy reserve is about 7.8MWh vs 8MWh
best at this date.

Then there is air quality, worst numbers I have ever seen. But
smoke containts physical particulate, which my electronic air filter
can remove no matter how small. The furnace blower operates it
around 20 minutes every hour. This really works, even before the
smoke, I could see that the dust particles in a beam of sun were
way down. The overall PV system produces enough energy to
allow this luxury (?) at no extra cost beyond cleaning the filter.
The blower motor (a standardized direct drive) was recently
replaced as the original was about to fail. All motor wires were
the same, though I did need to touch up the impeller balance.

Bruce Roe

[PNPmacnab]

Once again Nyle announced the e8 water heating heat pump adapter,
might soon be available. It is still in the process of being Energy Star
certified, UEF tested, UL tested, and other things. If I ever get one,
the energy reserve might be exhausted, better than giving it away.

IMGP2436.jpg

A friend of mine just got a e8 end of May and finally got around to installing it. He is quite impressed. He got build #4, just after the ones sent off for regulatory testing. So, I guess that is still experimental as it has no certification. Surprised it is a 120V unit with the market being primarily commercial. He uses it in singe pass full temperature output.

[bcroe]

This has been a year of very little rain, but local farmers managed to
get an average corn crop anyway. There were a lot of clouds that
did not produce any rain, just hurt solar. As of 1 Nov NetMetering
winter reserve matched my past best, 14,000 kWh. Usually it then
starts to reduce, but record warm weather and a few more sunny
days have it still holding 13 Nov. With any luck there will be plenty
of kWh thru this winter. Equipment has been doing well since the
switch repair.

Bruce Roe

[Rade]

Question: What is a "POCO"? It's not an acronym I am familiar with.

[Ampster]

Question: What is a "POCO"? It's not an acronym I am familiar with.

POCO is Power Company.

[Rade]

POCO is Power Company.

Merci!