Questions 12 Months On.

Mick-UK

Well it has been nearly 12 months since I made my last posting on this forum, since then the following has happened:

June 2009 a company called Solar Direct in Bradenton, Florida installed on the roof of our RV 3x 125watt Solartech Panels in frames that can be tilted.

Controlling the panels is a Morning Star Pro Star PS30M charge controller.

29th Aug 2009 both our RV & car taken to Brunswick port, Georgia, ship left port 3rd Aug.

We flew back to the UK on 24th Aug the same year.

Since then we have remained in the UK in order to attend two family events before resuming our touring adventures in Europe this Sept.

Now the solar array appears to be working correctly but then is it?

If you install a three bulb light in your home immediately you connect the light to power you see all three bulbs light or after time that one has failed, what about solar panels?

Now I appreciate a lot depends on our location, time of day / year and weather conditions as to what our three panels are producing.

I have sent a similar letter to Solar Direct but respect your views and opinions on a forum dedicated to solar power.

My only means of recording any output from the 3x panels is via the LCD display on the Morningstar Pro Star PS-30 but how accurate is that?

At 13.12pm 30th March 2010 on a bright sun /cloudy day the display showed 23.4 solar amps.

Can any forum members answer any of the following questions?

1. How do I know if all three panels are working?

2. What is the maximum power output of ALL THREE panels?

3. If one panel were to fail would the other two still operate?

Here are some technical details which mean nothing to me but may help you experts with my questions, please ask if more details are required.

Solartech SPM125P panels.
Power at STC (Pm) 125W
Maximum power voltage (Vpm) 18.0V
Maximum power current (Ipm) 7.11A
Open circuit voltage (Voc) 21.9V
Module efficiency 12.47%

Cheers Mick

BB.

Re: Questions 12 Months On.

Mick,

Nice to hear from you again (has it already been a year???).

Sounds like the three panels are working fine... 3x 7.11amps (Imp) = 21.33 amps in full sun on a clear day with a somewhat discharged battery bank.

Generally, if one panel fails, it will probably fail open (no electrical connection)--So you will simply have 2/3rds the current from the other two panels. Panels are pretty reliable--generally it will be obvious (rock through glass, "burned spot" under the glass, or a bad electrical connection somewhere.

If you can get to the wiring for each panel, the easiest way to confirm each panel's output current is to get a clamp on DC amp meter like one of these:

Extech 400 amp DC Clamp Meter

Around $100 in the US... Jeff (GreenPowerManiac) purchased one on EBay for $40. The meters are not perfect (DC clamp meters tend to drift from Zero Amps and you have adjust back to zero), but they are very handy.

The current meter displays on many solar charge controllers are not that accurate (can be off by 10-30%). At some point, if you want to know what is happening to your battery bank (current in and out, and estimated state of charge), a battery monitor is really nice:

NAWS Battery Monitors
Victron

-Bill

niel

Re: Questions 12 Months On.

as bb said it sounds as if all is doing well with the pvs. sometimes it isn't as simple as it losing an entire pv as the case of a cell or solder joint failing can cause a partial pv failure. shading a small portion of the pv can mimic this. the tolerance of the meters may overlook some problems, but most will be discernible by seeing the general trend of change that occurs in the readings during the same conditions as other times. this does not help you so much as it is only a cause for further checking, but the easiest test may be the short circuit current test during solar noon with the pvs aimed at the sun. they will vary a bit too due to solar conditions and even time of year so don't fret if it should show say .1a less than what the specs say as you aren't doing this under controlled conditions.
now i have to ask if they installed fuses for each pv as these should certainly be there? most cases could be a fuse failure causing a loss of an entire pv's output and you will generally see currents in the area of about 14a or so in such a case. if the fuses are good on the pvs then start suspecting wiring, connectors, or even the pv itself. checking the pv may prove easier than wires and connections, but we hope it never gets to that point. this will mean for you to purchase a good to semi-good digital multimeter and learn how to use it or the use of the clamp-on ammeter will take away some fears of doing it wrongly that could cause damages if done wrongly at the expense of accuracy at times. the isc test can be done with the clamp-on meter too, but this will need the wires to be opened to the rest of the system so that only this pv will be tested. it's rather difficult to explain everything in type and hopefully you understand enough to do this, but we will still be here if further questions would arise.

Mick-UK

Re: Questions 12 Months On.

Niel & Bill,

Thanks guy's for that quick reply to my question, yes doesn't time fly.

As stated in my original posting I also sent a similar email to my solar installer Solar Direct who gave me similar answers.

Since we bought the RV one device I bought before leaving the US but have only recently fitted is a Xantrex Freedom remote panel.



This device allows remote switching of the charger and inverter and is fitted as standard to some RV's.

Now since the better weather has arrived in the UK I have been able to switch off the RV's Xantrex Freedom 485 inverter/charger,and charge the 'house' batteries entirely with the solar panels, this allows us to use higher amperage items on out UK 16amp EHU*, however during the night with everything 'possible' turned off we incur what is called Parasitic Current drain.

Now at present I only know this due to the Xantrex Remote panel battery state display changing from green to amber and the battery voltage percentage having dropped.

I am considering adding a NASA BM-1 which monitors battery discharge as well as charge.



Boy's and their gadgets eh?

* Immediately on our arrival in the UK I had a step down transformer installed into our American RV, this allows all the RVs electrical devices microwave,fridge/freezer,kettle etc to work on 110v , in fact our UK 16amp @ 230v with the transformer equals 32amps, not quite the 50amp EHU we have been use to in the US but still good.

The problems start when we visit Europe with EHU's of 2,4 and 8 amps.



Mick

niel

Re: Questions 12 Months On.

you're right time flies.
as to this, "Parasitic Current drain" we call those phantom loads. like we turn off the tv with the remote, but it still drains some power to keep the sensor functioning to allow the remote to turn the tv back on. clocks are often overlooked too, especially on microwave ovens.
just to clarify and keep me on the same page here, just what is an "EHU"?
if i understand you correctly then i'm also going to say that if you use american appliances in the rv and just use a transformer to bring the european voltages in line that the frequency will not be correct. many items will work, but some are sensitive to the frequency difference. clocks especially.

Mick-UK

Re: Questions 12 Months On.

Niel,

I see why you are a moderator on this forum, yes you are 100% correct with our 230v UK supply being transformed to 120V US all the 120V appliances work okay that is unless they have a timer installed then they either run fast or slow because of the 60 Hz (US) and the 50 Hz (UK) difference.

However just to contradict the above whilst in the USA we purchased a US Pansat satellite receiver which has a clock and keeps perfect time

EHU means Electric Hook Up you get at camp grounds, you guys in the States & Canada are lucky to get 50 or 30 amp hook-up for your RVs here in the UK the maximum is 16amp.

Further to items other than those you mention which cause Parasitic Current drain in most RVs there are C02 detectors and smoke detectors.

Now our RV has a double Norcold fridge / freezer which will operate on either LPG or 120V mains electric, however the fridge / freezer will NOT operate on either if there is NO 12 volt input so that must be a further continual drain on the house batteries.

Mick