solar panels

[W9LCE]

In the light of current advances and market

What is a good solar panel?

I am running a 100w rig off of deep discharge batteries.  What do you recommend?

Cliff
W9LCE

[W1ITT]

I'm about to drop the hammer and buy an AltE 140 watt panel from these guys.  A good part of the reason is that the Genasun $100 mppt charge controller that they offer with it is reputed to be radio-silent.  Many of the controllers, being solid state wonder boxes, make a nasty RF racket. 
I will be running a 100 watt station, occasionally, in a camper at a location where mains power isn't available.  With a fat battery and sunny skies, this should suffice.

https://www.altestore.com/store/solar-panels/alte-poly-140-watt-12v-solar-panel-p11564/

https://www.altestore.com/store/charge-controllers/solar-charge-controllers/mppt-solar-charge-controllers/genasun-solar-charge-controllers/genasun-gv-10-pb-12v-105a-mppt-controller-for-12v-lead-acid-batteries-p10626/

[flintstone mop]

Solar Panels and or their controllers....cause a lot of RFI... there was a good article in QST about whole house systems and the efforts to get rid of RFI.

Something has to protect the battery / batteries from over charging when the panel is active...

A small field day system and inverter / battery might still need the Charge Controller.

I'd love to go green and be off the grid,,,but the cost is out of this world.

[KD6VXI]

I do solar installation.

I prefer Enphase micro inverters and LG panels.   They are the most efficient I've installed to date.

Canadian solar is another good panel.   Less expensive,  but not an inferior product.

I much prefer micro inverter to a string setup.   Without using power optimizers,  a string setup is a very inefficient way to go.   With optimizers,  your adding a couple years to your ROI.

I use all aluminum racking,  rails and feet.   Flashing are all steel.   All grounding is run I SIDESWIPES of the piping,  and I require my guys to bind with grounded bushings both ends of the pipe.   Reduces rfi,  and will be NEC code on the next round (next year.   Bonding both ends means you don't have  choking effect of an open ended pipe with a conductor inside).   Some jurisdictions already require this.

If you have any other questions,  please feel free to ask.

This is a non battery system,  as well.   
--Shane
KD6VXI

[K6IC]

Cliff,

For 100 W 12 V powered radios,  would suggest one or two PVs.

The highest quality PVs for 12 V system voltage is probably Kyocera brand,  like this one:
http://www.solar-electric.com/kyocera-kd140gx-lfbs-140-watt-polycrystalline-solar-panel.html

Most of the less expensive real 12 V PVs come from China.   The Chinese CAN make good products,  just difficult to know about the current quality levels of many of them.

Would suggest a PWM Charge Controller (CC),  as they make much less HF radio noise.

MPPT CCs do work magic,  but they are switchers,  and because they only connect to DC cables,  FCC Class B emissions standards/testing begins at 30 MHZ.   So any emission suppression is focused above the HF bands,   and omits, by far the worst Emissions  --  Conducted emissions on all attached cables,  primarily from the PV module cables.

MidNite Solar has a smallish PWM CC,  the Brat for modest sized systems.  Morningstar makes a number of PWM CCs:
http://www.solar-electric.com/inverters-controllers-accessories/chco/misoclchco/midnite-solar-brat-pwm-solar-charge-controller.html

We do have two off-grid QTHes that each use a pair of MidNite Classic  MPPTs each.  These CCs are rated up to about 4 kW output,  each,  so without additional suppression of RFI they do make a bit of racket,  as do all other MPPTs  that I have looked at.

The emissions from large MPPT CCs can be well tamed,  but it takes a bit of effort.

FWIW,  I have no interests in any of the above companies.  GL,  Vic

[W9LCE]

Thanks

From net sources - one comment was - to use an American manufacturer  (which I have previously followed)

Other information (MIT) gave SunPower efficiencies at over 21% - and SolarCity slightly higher
but the comment was made that reliability was more important than efficiency

one panel or two? - I have 4 golf cart batteries (6v) - hooked up 2 in parallel - in series -to give me the 12 volts.
I know I don't operate as much as I used to - but I am very interested in being prepared for emergencies.

Cliff

[W6TOM]

  You might contact Palomar Engineers, the owner is a ham and he gave a good talk on RFI suppression at the Yuma ARRL Convention last winter, he told a few stories about RFI issues he was able to eliminate on some solar systems in Southern California.

[K6IC]

Thanks

From net sources - one comment was - to use an American manufacturer  (which I have previously followed)

Other information (MIT) gave SunPower efficiencies at over 21% - and SolarCity slightly higher
but the comment was made that reliability was more important than efficiency

one panel or two? - I have 4 golf cart batteries (6v) - hooked up 2 in parallel - in series -to give me the 12 volts.
I know I don't operate as much as I used to - but I am very interested in being prepared for emergencies.
Cliff

Hi Cliff,

Would not get too hung up on efficiencies,  and SunPower does not sell any PVs into the Retail channel,  essentially only to Pro Installers.   AND,  none of their PVs are real 12 V or 24 V (ie,  about 18.5 V Vmp,  or about 36 V Vmp for 24 V).

You can use the NREL PVwatts2 estimator for your QTH (or close to it) to estimate the Solar Insolation averages by month.  The dataset for this program has historic actual data,  including weather effects,  etc for many locations in the USA.  The data is much more oriented to Metro locations,  but is quite useful for PV array design.

As you know,  PVs are rated using a Flash Tube,  with PV cell temperatures of 25 C,  this is referred to as Standard Test Conditions (STC).  In full sun,  the PV cells run hot,  and this reduces the output to about 77% of the STC value.  With warm/hot ambient temps,  this output is further reduced.  PVwatts2 takes all of this into account,  and usually errs on the side of showing a bit less power from an actual PV array than the typical user's PV array actually produces.

PV array sizing all flows from the loads on the system,  and to a small extent,  the nature of the batteries being used.  Your GC2 batteries are really very good  --  they are true Deep Cycle batteries,  and are a very good value for the battery Capacity.

In sunny weather,  most reasonable sites will get about 3 hours of good sun ...  often,  a bit less in Winter,  even on sunny days.

The amount of rated PV power that you will need,  really will depend upon the loads,  of course.

As you probably know,  you really do NOT want do discharge your GC batteries below about 50% State Of Charge (SOC),  as this can easily damage the batteries,  and will reduce the number of discharge cycles that the batteries will deliver,  before failing.

Parallel battery strings can be a challenge to manage,  as batteries characteristics will diverge over time,  causing poor current sharing on charge (the primary problem),  and also on discharge.

Using a DC Clamp Ammeter/DMM  will help you monitor current sharing on charge and discharge.   Sears and RadioShack have had 50-ish dollar DC Clamp meters that are quite acceptable for this monitoring.

And so on ...  just my take on things.     FWIW,   GL,   Vic

[flintstone mop]

Thanks

From net sources - one comment was - to use an American manufacturer  (which I have previously followed)

Other information (MIT) gave SunPower efficiencies at over 21% - and SolarCity slightly higher
but the comment was made that reliability was more important than efficiency

one panel or two? - I have 4 golf cart batteries (6v) - hooked up 2 in parallel - in series -to give me the 12 volts.
I know I don't operate as much as I used to - but I am very interested in being prepared for emergencies.

Cliff

Don't forget the controller (?)...it has to regulate how much the panel charges the batteries. The solar panel is relentless output when the sun is shining. The poor battery will boil to death, without a "watchdog" / controller

[K6IC]

And,  Cliff,  to finish a couple of thoughts;

If you choose real 12 V PVs,  then a Pulse Width Modulation (PWM) CC can be used with a 12 volt battery system.   PWM CCs are efficient,  and perfectly adequate at the power levels that you should need for running a 12 V radio,  and a light or two  --  just basic stuff.

The least expensive PVs are usually what are called 60-cell PVs.   These have a Vmp of about 29.5 - 31 volts.  The 72 cell PVs are becoming popular again,  often in the power range of about 280 - 300 watts.  These would require an MPPT CC for use on a 12 V system.  Real 12 V PVs have a Vmp of about 18 volts,  if they are currently produced models.

Many of us have run 12 v radios on 12 V batteries.   Many of these radios often do not make full-power,  and can have high IMD of the transmitted signal,  because a 12 V battery that is not being charged,  or maintained will  usually have a resting voltage of about 12.8 volts when it is at about 77 degrees F.   Some,  use a switching voltage booster to alleviate this issue.  Some of those boosters can create quite a bit of RF hash,  etc.

I believe that some transceivers that are designed for Mobile use,   might   possibly perform better at about 12.4-ish volt input from the battery,  than 12 V base radios.

Most fully-charged Flooded batteries (ones with easily-removed caps)  batteries that are good,  will have their terminal voltage sag to about 12.4 - 12.5 volts (at 77 F),   soon after a load of about 20 Amps,  or so,  is applied.   This seems to also be the case when using batteries with fairly high Capacity.   Your four GC2s in 2S2P configuration should have about 430 - 470 Ah Capacity.

If your batteries are in a place with fairly large temperature variations,  it is probably a good idea to use a CC that can use a Remote Temperature Sensor (RTS or BTS).   These would normally be an extra cost option on most PWM CCs.   Many Flooded batteries need to have charge voltages compensated at about  30 mV per degree C of battery temperature change from the Reference temperature (77 F,  or perhaps 80F  -- 25 - 27 C).

Regarding one or two PVs,  this really depends upon the amount of Ah that you will need from the batteries,  of course.  If you would be willing to wait several days for Solar to recharge the batteries,  then perhaps one 140 watt PV would be adequate.  Having a small generator that could run a TV,  your radio,  and perhaps a frig,  might be a good thing to have,  as it might also be able to do some battery charging,  if needed.

The Honda,  or similar Inverter generators can be very important,  especially in a prolonged outage.   An EU1000 Honda is amazingly capable,  and weighs only about 30-ish pounds,  wet.

Most Inverter gensets can create quite a lot of RF hash,  but it is fairly easily suppressed to acceptable levels ...   and so on.

Most/all of this is well-known.   FWIW,   Vic

[W9LCE]

Thanks again

While I had heard some of this, I've learned a lot - I think I will go with 2 panels - trees are nice, but there's only one place here, where there is space for a couple panels to get good sunlight, till about 2 PM.

I knew of the PWM controllers, and that they were "better", but not a lot of expanation, nor makes.

Cliff

[KD6VXI]

http://www.eham.net/reviews/detail/12862#141708


Maybe this will help.  Seems it's RFI free.

--Shane
KD6VXI