Spring is in the Air

[DamonHD]

It may be below freezing outside and still part of the coldest winter in the UK for 30 years, but it must be Spring because for the first time since I bought my Morningstar MPPT I got all the way to 'float'.  Hurrah!

And now I'm going wild using my 9W LED 12V desk light to work by.  My, how us youth burns the Joules...

Rgds

Damon

[Jon Miller]

Freezing weather + clear sunny days = MPPT joy.

 

[gotwind2]

Agreed.

Cold and sunny weather is the best for solar PV panels.

Add some snow, and the added reflection somehow increases output even more, that's what i found anyway.

I think we have had enough snow this year in the U.K anyway :-)

Ben.

[FishbonzWV]

It's been a nasty winter here too.

Last month we set a new snow fall record and the AVERAGE temp was 30 degree F.

(Freeze point is 32 F. for you Brit's.)

There were only four days in twenty eight that the sun even peeked out.

It got mentally tiring shoveling snow off the walk and vehicles every morning.

This weekend though was blue sky with nary a cloud in sight. Yeah!

Bonz

[richhagen]

Here's my take on it:

In the interest of full disclosure, I did a bit of tinkering with my system during this period, as it seems I always am doing, but that doesn't account for the overall trend upward.  This data is for my 48V system here in Chicago, and it is solar only.  You can really tell the rainy period we had at the end of March and the beginning of April.  This year, as last, I can tell the days are getting longer as more excess is dumped as heat.  Rich

[tecker]

Yes we would vote you as Mr Green Jeans If we were in the area.

  Wholesale solar will be shucking last years stock and I'll recycle to get a unit .I can relate .

[DamonHD]

Excellent point, which I hadn't fully considered!

Rgds

Damon

[DamonHD]

Time to change the year on your graph?  B^>

I'll bring my graph up to date and post it and we can compare...

Rgds

Damon

[DamonHD]

http://www.earth.org.uk/WW-PV-roof/data-PV1/E2010.gif

Rgds

Damon

[Capt Slog]

Yup, it's been nice to get a bit of sun on the panels this last couple of weeks.  January was a very lean time; almost no wind and little sun for a several days at a time had me connecting up a mains powered charger to save the batteries.

I'm running nothing like Damon (little out and only 2 x 80W of panels) but I'm pleased that I don't depend on it.

[richhagen]

Hi, I haven't captured daily data this year, so I only have last years to look at.  It looks like you had a bit of snow about January 5th or 6th there, and it also looks like your getting a bit more of seasonal bump there than I got here last year.  You are at a more northern latitude though, so I guess that makes some sense.  Either that, or you've just been experiencing an unusually sunny period the last few days.  At any rate, the trend looks good. Rich

[DamonHD]

We probably did have snow then.

Also, my PV sections are east facing (2/3rds) with some shading to the south, and west facing with no shading.

The direction and the shading increases the drop-off in winter to about 10+:1 c/f 5:1 for south-facing, but seems to reduce total year-round generation << 10%.

Rgds

Damon

[DamonHD]

I had to move my little ShivaPlug from my off-grid solar and back onto mains for half of December and most of January, partly to save my battery (it got right down to 11.5V more than once) and partly later to conserve some battery power for lighting if we did have the grid go out which looked possible.

The off-grid system has mainly south-facing panels but even with a big boost (having talked my local Maplin manager into a fat discount on their 60W kit) it just couldn't keep up.  Short of 6 weeks' battery to carry through the worst (4000Ah+!) I don't know what else I could really have done.  Until I make a server that runs on 2W I suppose!

Rgds

Damon

[DamonHD]

Sorry, brain-fart there.

10Ah is about a day's draw (10Ahx12V is 120Wh, device draws < 100Wh typically).

So 20Ah covers 1 day with less than 50% DoD.

My current 40Ah covers 2+ days in practice.

To cover 6 horrible weeks in winter = 42 days => 42*20Ah => ~800Ah.

And indeed I have considered such a monster, ~1/4 ton(ne) and £1200, ie more than the rest of the system...  And that wouldn't even run the ADSL modem (draws twice the power of the server) so who am I kidding?  B^>

Rgds

Damon

[DamonHD]

On the other hand, a couple of new MasterVolt MLi 12/320 Li-ion apparently SLA-drop-in-replacement batteries (2000 cycles at 80% DoD, ~3.4kWh) would be 2 months' of run-time for my little system even in the darkest.

Just saw these a few minutes ago...  Hmmmmmmm....

Rgds

Damon

[DamonHD]

£4,600 list price I am told, BTW...

So somewhat over £1/Wh.

Rgds

Damon

[DamonHD]

MasterVolt has just confirmed to me by email that their battery can be used as a drop-in replacement for an SLA with a PWM solar controller.  I'm now trying to get MV to suggest what round-trip efficiency it would expect in that configuration, ie will it be over 90% still.

Rgds

Damon

[DamonHD]

Going to have to take some of my 'winter' solar panels off since my battery is full most of the time and the wind turbine SCR crowbar protection is repeatedly triggering, which isn't very good though it proves that it all works I suppose!

At the moment to counter that I have this laptop, my ADSL modem as well as the server off-grid as a manual dump load, and it's still not really enough!

Rgds

Damon