Small solar PV

[tanner0441]

Hi

I have 3 x 20W solar PV panels total 60W with an EPIP20 PWM Charge Controler. Because of the way the manufacturers measure panel output, I was more than happy when it was outputting 40 to 50 Watts. Then the other day I looked at the Ammeter and it was nearly hard over, 4.5 Amps rapid poking of the calculator buttons 4.5A x 13.2V and found out it was managing just over 59 Watts.

I kept monitoring the meter and watched as the batteries 3 x 115 AH sealed lead acid became more charged the controler dropping the power back to just over half an amp over 3 hours, then the sun moved too far to the side of the panels to be of use.  The controler takes the batteries to 14.5V before it starts cutting back, you can see the meter dip every few seconds.

Combination of the PV panels and the intermmittent bursts of useful output from the wind turbine and I have managed some 30KwH from the inverter (600W pure sine wave) since the start of the year. Pity it all cost so much, but it is good fun and even just running the lights on an almost nightly basis never fails impress the doubters.

Brian

[Ungrounded Lightning Rod]

The output will drop somewhat, on hot days and as the panels age.

Glad it's working out for you.

[taylorp035]

My 15 watts solar panel never gets close to its rated output.  The most I have ever seen was about 11 watts, even when perfectly positioned on a 60 degree day and super clear sky.  I think someone should have an independent testing lab for solar panels for consumer awareness.

[DamonHD]

PV will typically need to be dynamically operated at the maximum power point (ie by hunting for the right V to maximise V*I) with an MPPT controller to hit the ratings: a dumb battery load will lose a little of the potential available power.

Rgds

Damon

[Jrmobb]

Sounds like you got lucky. Congrats

Lets see some pics of the new setup!

[Yyrkoon]

We have ( in eastern Arizona ) roughly 2KW peak worth of panels up on our two story building. With the panels being angled to winter maximum, and the heat of the sun on them, we're lucky to see 800W when the sky is cloudless. Most of these panels are very old commercial panels; branded by Arco. 2 are brand new last year, and first installed summer this year, and 180W peak per ( not sure of brand ).

Anyways, we store this power into ~1600 AH worth of batteries ( yeah, definitely not enough ) which powers lights, a 7A startup / 2A continuous draw freezer, and 4 laptops through the night. Some nights we make it, some we do not, and have to fire up a small generator to charge batteries.

Anyways, the point I am trying to make here is that the idea of solar is great, and it works most of the time. However it is not for those who require tons of power on a daily basis. Unless you can afford to spend what you need for your power needs. I am not sure what we here would have done if a good portion of the equipment here was not free. On the flip side; We recently met a lady not far from us when we were at her place on business. She had 5KW peak worth of panels, roughly 48 L-16 batteries, and a very nice outback inverter/controller( sorry did not get the model ). Anyways, she invested A LOT of time, and money into this system just to run 2 refrigerators, and it was not working for her a lot of the time. So I suppose this type of person would benefit less from such a great system; and she was saving money, although still unhappy about it.

Still, it is great to be completely off grid, and we have yet to tap into wind  of yet ( too many other priorities ), but we will. Then I suspect, things will become much, much better concerning power. Especially since the wind is so plentiful ( with a utilities wind farm being built within 15 miles from us, and in view ).

Oh, and about the controller watt meter being inaccurate ? I have been told this is a common occurrence, and that you should pay more attention to the AMPs out, and do the math yourself.

[tanner0441]

Hi

To measure the amps I have an analogue ammeter inline with the feed from the panels.  The whole setup has been in place since last year but only recently been in a more optimum position, south facing and at the correct angle, no problem, but now I dont have the shade from a neighbours tree on it half the day. No one has ever had my attention so fast as when he asked if I had a chainsaw and winch.

As I said I was happy with 50W. I tried 2 controlers but the epip20 seems to do what it says on the box it is PWM not MPPT so I never expected anything like the panel rated output.

The thing is realy a hobby with  me but with the wind turbine I have (chinese Bergy look alike) I have had a lot of fun and learned a lot, and re remembered a lot of stuff I learned at school and college, and a lot of new stuff from this site.

Brian.

[Yyrkoon]

I think I misread your post. I thought I had read something about a watt meter disagreeing with your calculations. Sorry about that. At the same time, I also did want to relate two other "stories" on the subject. I think I did that

Another thing I did not mention was that when your panel surface area increases, or perhaps just more powerful panels ( many of them ), you can also get an amazing amount of power when it is even raining. Of course "amazing" is subjective, but in our case pulling in 300W + on all but the darkest days is still very cool. That is, until the sun goes down, and then you just know the generator is going to have to be started. Also in our case though, we use a shop type battery charger ( 2,4,10,40, and 200A selectable ), and a very cheap ( sub $150 USD ) 1250W peak 2 cycle generator. It'll run 4 hours on just short of 1 GAL of mixed gas, putting out 20A according to the meter on the charger its self. 80AH may not sound like much, but it keeps the system running. Anyways, the good news is that two of us are small engine mechanics, and have maintained the generator to last a year so far. Probably the best money spent here so far concerning keeping the batteries in charge.

Also, we did install this system ourselves, so we saved another "boat load" of cash there. Luckily one of my buddies who also lives here is an Electronics Engineer, and has years experience with that, and electrician type work. Now, we're trying to work out the details of pumping water 500 FT up from a well, to fill 3-5 small ponds for irrigation. Lots of back yard "engineering" going on here I am not sure what I will do with my time after all of it is done, but it will probably will have to do with wind power.

Most of our batteries are also the 115AH filled lead acid type. Wal-Mart deep cycles that have managed to last 3 years ( some of them ). Just temporary though, until we get enough cash to get "the good stuff". We did mix in 4 L16's but they were free, and make an obvious improvement in our storage. Not something I would personally do if I were paying for everything, new, but they all do their job.

Anyways, it is nice to see other people having fun with solar, and I have rambled on long enough . . .

[OuttaSight]

Trees...  The day my neighbour planted some horrible really fast growing coniferous things at the end of her garden, my heart sank.  It's been there one season and is already 2m high.  I might have to have words with her about keeping it in check or else bill her for building a 30m tower in my garden to put my solar array on...

[OuttaSight]

If they're the same cheap Chinese amorphous ones that I bought at first then that's as good as they get.  After a few months in the sun they decayed to 64% of their day one power (on a MPPT controller).  They've stabilised now but the manufacturer declared the 15W as the day one power (not the stabilised power value). Cheaters!

Now, I've got some Sharp panels and a couple of Kyocera ones and a BP one.  A pair of 170Wp Sharps I bought new but the rest have been much cheaper used ones off of eBay.  They are all polycrystalline ones and all put out at least their rated power (on a good day, despite some being used for 4 years already).  In fact, on partially cloudy days the new Sharp ones can put out 118% of their rated power due to light diffraction focussing at the edge of clouds.

Depends on where you live as well (not just latitude but how hazy and polluted the air is above you).  We live out in the countryside away from the brown haze of London.  If we lived 25 miles further south on the south coast they have a micro-climate there because of a ridge of hills to the north that means they get the least clouds and most strong sun in the whole of the SE of England.