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indicator |
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NKF
PV-power indicator. This one was shipped together with my own PV
panels. The indicator starts blinking as soon as the PV panels start
producing electricity. At high production levels the indicator light
is continuously on. Advantage: very simple. Disadvantage: too expensive
for what it does, notably only informing you that 'electricity is
being produced'; it does not say whether all panels are producing
and how many Watts each panel produces. Power consumption: nihil. |
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Indicator-meter |
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The
Variwatt (Beldezon)
measures the yield in kilowatt-hours. It is equipped with a LED
that blinks green when the panels produce electricity. Advantage:
simple and sensitive, and the production in kWh is being monitored.
Disadvantage: it does not display the load. The device does not
provide an indication whether all panels are active and how many
Watts each panel produces. Expensive gadget. Power consumption:
nearly nihil. |
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Experimentall |
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This
is a so-called Web'Log given on loan to a selected number of Dutch
owners of PV panels by Utrecht University. The project is called
PVSAT (www.pvsat.nl).
On the left is a kWh meter which is connected to the Web'Log. The
latter device is a logger and a modem. During daytime the logger
logs the performance. At night the modem part transfers the logged
data to a server in Germany (www.meteosat.de).The
server at Meteosat compares the performance of the PV system with
satellite data and local data on insolation, prepares a report on
the website of meteosat and rings the alarm if the PV system underperforms.
Power consumption: nearly nihil. Phone costs: one international
call to Germany each night. |
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OK4E
manager |
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| My first
six PV panels were equipped with NKF OK4E inverters. These devices have
a built-in communication module. Unfortunately two of the OK4E's stopped
working after three years. These have been replaced by Sunmaster 130's |
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NKF inverters
are equipped with a built-in communication module. All you further
need the odd-looking OK485 RS485-RS232 interface shown in the inset
(figure B), and connect this device with a PC. This device works
therefore only with NKF's OK4E inverters. The interface links inverters
(minimum = 1 maximum = 128) via two color-coded data wires with
the PC's serial (COM, RS232) port. Windows 95/98/ME/XP software
(OK4 manager by NKF) displays the data in a very user-friendly way
(figure A). Advantages: all important data: performance, production,
temperature, are displayed for each panel. Disadvantage: you need
a PC that may consume more electrical power than the panels produce
(!) The inverters don't work at night or under poor light conditions,
and it is then impossible to measure. Power consumption: nihil.
Bang for the buck (only if you have OK4E inverters |
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Performance
meter |
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One
solution is to plug the 230V AC inverter cable into an electronic
device like the Energy Check 3000. This device is part of Sun
Kit systems marketed in Holland by Oskomera Power Solutions.
that displays time, load level, yield in kWh, and it also calculates
the avoided emission of CO2. These devices are very accurate and
sensitive, and all relevant data can be displayed. Disadvantage:
quite expensive gadget (€ 75), individual PV panels can be
measured only when you plug this device into the outlet of their
individual inverter. Power consumption: 1.8 W according to the manufacturer.
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Easy
fix |
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The Conrad
company sells this meter for € 25. It looks exactly like
the one in the previous image. However, this meter is a consumption
meter, not a yield meter. Soembody found out that if you open
this gadgeta nd you swap two wires, the result is a genuine performance
meter, exactly as the one above. Power consumption: 1.8 W according
to the manufacturer. Cheap
and reasonably reliable.
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EM-600 |
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The
EM600 device is an electronic measuring device that displays time,
load level, yield in kWh, and it also calculates the avoided emission
of CO2. Advantage: very accurate and sensitive, and all relevant
data are being displayed. Disadvantage: very expensive gadget, individual
PV panels can be measured only when you plug this device into the
outlet of their individual inverter; there is no reset button (!).
Power consumption: negligible. I had one and it stopped working
after one year. |
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Telemetry |
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Wireless!
The LI-12 unit sold by ALL4Solar
consists of two parts: a small transmitter (a small black box plugged
into the wall outlet; the plug of the cord coming from the solar
panels is plugged into the transmitter box) and a receiver/display
(shown on the left). The display can be placed in any place, e.g.
the living room. It displays performance, yield in kWh, and it also
calculates the avoided emission of CO2. Advantage: very easy to
install, and absolutely no wires. Disadvantage: rather expensive
gadget, individual PV panels can be measured only when you plug
this device into the outlet of their individual inverter. The receiver
needs 3 AA batteries (battery life unknown). The transmitter consumes
very little power (<2W according to the manufacturer). Transmission
range depends on the local circumstances (objects, steel or concrete
between transmitter and receiver, etcetera). Maximum load is 2400W. |
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Indestructible
old hand |
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The old-fashioned
but unbeatable (used) analog kWh meter. Available (sometimes)
for little money in the 'Kijkshop' or in an emporium. Remove the
seals (this thing is yours isn't it), turn the dials back to zero,
and connect 'reversed' to the 230V part of your PV installation.
If everything works out fine, the device counts the kWhs produced
and the little horizontal wheel turns in proportion to the amount
of electricity being produced. Advantage: ultracheap. Disadvantage:
not particularly accurate, and it consumes some electricity, even
at night. WARNING! This is 230V equipment so this is stuff for
certified electricians.
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Watch
out! Do not tinker thoughlessly with electricity and electricity
meters. Ask a certified engineer This is stuff for professionals,
not for amateurs. |
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All
kinds of nice and fancy displays |
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| In addition to these
pieces of equipment there are fancy digital displays made on individual
order. These displays may provide the audience in a highly visible way
with all the data that are relevant: power level, kWhs produced, avoided
CO2 emission and so on. Examples are the 'Edisun' and 'Eclipse' displays
sold by Beldezon
and E-conergy or
the fancy PV-display 'Zonnestroom' marketed by Buro
Wilders. Advantages: Sexy, representative, irresistable, wonderful.
Disadvantage: prices are in a range not affordable by private persons.
These are displays that typically fit the mighty installations on businesses,
schools, public building and so on. Professional measuring instruments
can be appreciated as well at Leiderdorp
Instruments (site in both English and Dutch).
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