More array? More Battery? More Generator?

morpho

Ok, forget the generator I am tired of generators!

so I was looking at the current panel prices (shockingly low) and the LA battery prices (still costly) and I have had a truly horrible grey winter so far and have had to run my little generator way too much for comfort.

So I was thinking (always a bad sign) that if on a grey day I have 5 amps coming in on my 3kw array...what if I just add a buttload of panels...say...quadruple my array. I know there are many things to consider, but if I have 5amps coming in now on a grey day and I quadruple my array...I basically would have the same amps coming in as I have on a sunny day. (throttled back to 25amps to keep my batts happy)

What are the downsides of this tactic instead of a better batt bank? 

Cheers.

Marc Kurth

I sell batteries for a living. But I send more customers down the road with the suggestion to buy more PV than batteries, after listening to their story.  The biggest single problem that I see is undercharging of batteries, because people all too often buy more batteries when they don't have enough power.......

There is wisdom in the old adage: "Make hay while the sun shines" 

morpho

+1 for more PV.

I don't suffer from lack of power for 8-9 months a year...but man alive those 3-4 months of darkness!
I try to never let my batteries to get below 80% SOC. Basically use the bank to keep the food from thawing through the night etc...and pray for sun in the winter and if there isn't any I fire up my little generator to fill the gap. Basically, I treat it like I don't have any days of back-up. If I could add panels to the system and put less burden on the generator, now this would be great. 

mcgivor

Generator : gas costs money, take into account losses you are probably throwing away around 70% of every dollar spent, there is wear and tear, maintenance, not to mention labor and noise.

PV: Sun, what little you have right now, is free, losses don't cost you $, maintenance involves cleaning, will probably outlast the generator, and that deafening silence.....+1 for PV? 

Photowhit

I'm 'over paneled' and likely even a bit more soon. I think it's smart, particularly if you can pickup deals as you go along....

Dave Angelini

There are 2 kinds of people, those who want solar, and those who want more. 
I spent many years repairing other peoples marine generators. That is the last thing I want to do now!

mike95490

I've overpaneled a bit, but still run the generator.  At least panel cost has come down some.

morpho

so far so good..nobody saying outright that I am on a fools errand.
Thanks everyone for your insights.

Hey Mike95490:
I see you have a lister cs 6. How is that treating you?

inetdog

Marc Kurth said:

I sell batteries for a living. But I send more customers down the road with the suggestion to buy more PV than batteries, after listening to their story.  The biggest single problem that I see is undercharging of batteries, because people all too often buy more batteries when they don't have enough power.......

There is wisdom in the old adage: "Make hay while the sun shines" 

There was a time, several many years ago, that system builders tried to make up for inadequate PV or turbine output by designing in larger battery banks. The predictable result was that either people actually cut back on their usage and got only the benefit of running occasional large loads from the battery bank or they ended up with chronically undercharged batteries and had to use a generator anyway.
Fortunately there are a lot more people now who know the folly of that approach.

Marc Kurth

I can assure you that I still see chronically undercharged batteries on a regular basis. Even a well designed system can suffer from load creep. Over time, typical homeowners always seems to find more "must have" items running on the inverter. Folks who design/build their own don't tend to do this, but others most certainly do.

Non technical homeowners don't tend to watch their battery banks like people here do!

morpho

Ahhh load creep...Yah I have added a strip of heat tape for my water line that is doing my head in! Sucks 3% from my bank through the night. And the Mrs wanted a TV. So we've got one of those now. STOP THE MADNESS!

Anawa

Looks like I will too be "paneling-up" in the few months. I'm at a marginally acceptable balance with what I have right now: good weather, sunshine, no problem. But, I don't like powering on the generator either on the gloomy days and I agree with everyone's statements above.

I thought morpho asked a very good question: would more panels on gloomy days proportionally increase the amps going back into the batteries? Anybody willing to opine?

softdown

"So I was thinking (always a bad sign) that if on a grey day I have 5 amps coming in on my 3kw array...what if I just add a buttload of panels...say...quadruple my array"

Are you being serious.....quadruple? I would strongly gear your panel addition, everyone agrees this is the right thing to do, towards optimal winter production. I believe that is latitude plus 15 degrees. Summer optimization is latitude minus 15 degrees of course. Plus the steep panels shed the snow and soak up the winter sun to melt the ice off.

Assuming 45 degrees latitude, (I have no idea), then 60 degree panels would be dynamite from Nov-Feb.

FWIW....only south facing panels gather enough solar heat to melt off snow and ice effectively. East and west panels just suck during northern winters.

If doubling the array doesn't do it, I might take a closer look at a propane genset if you can buy bulk propane during the summer....I paid $1/gallon last August. Diesel just doesn't like weather below ~10-15F.

mike95490

The lister is the reliable genset, fired on the 1 compression crank this AM in the snow,    Panels covered, was getting maybe 100w from 5KW array, under 1" white reflective snow. Should warm up and slide off later today,

Mangas

Looking through the discussion, I think I'll also add a couple panels to one side of our system to bring charging up a little on that more heavily used battery bank.  

Winter overcast days and shorter charging hours are tough even here in Arizona.

Photowhit

morpho said:

"...and I quadruple my array..."

Let's see if that would work.... Yep, still be able to park...

cupcake

Size your panels for a grey-day on the winter solstice.  You'll be set the rest of the year.

morpho

I was thinking more like this...who needs room for a car if you have that much power? No power bill, I'd have enough power to run a 12 month greenhouse...I wouldn't have to actually drive anywhere! EVER!

morpho

I know quadruple sounds like a crazy thing to do, but if the cost is roughly equal to the cost of a proper diesel genset, and on a cloudy day I get roughly the same amount of power from the array as I would from the genset and the same amount of power from my current array on a sunny day...well then it seems like a no brainer.

morpho

Mike:
sweet looking CS 6/1. I love the sound those make. I have often thought about getting one and planting a couple of acres of canola and pressing my own oil to feed the beast.

westbranch

Morpho, you did not mention how the 5 amp array is set up...  Is it optimized for winter production, the equinoxes or summer production?  if it is not the first of the 3, then , yes, at least 2 more oriented and angled for maximum winter production (on Dec 21) would be my choice..

morpho

The rack is set for winter and I change it for summer. (I'm at roughly 65º Latitude.)

 

mike95490

I have array tilt set for winter, and leave it there,  summer there is more then enough sun

here's some numbers to size your panel with
Array 5Kw PV (2 arrays, 2 controllers, 3Kw & 2Kw)

Winter cloudy day  1,010wh  (Dec 15 2016)  rain
Winter sunny day 17,880 (Dec 16 2016, charging up that flat battery)

And we often have a week of solid clouds

average winter usage 7Kwh (house, shop, 2 fridges, 1 freezer)

softdown

morpho said:

The rack is set for winter and I change it for summer. (I'm at roughly 65º Latitude.)

 

Tough latitude solar wise. You get 4 times the sun during the summer solstice.

On the bright side, you could attach panels to exterior 90 degree walls and have good effectiveness with almost no snow/ice.....I would think.

morpho

It's true, my rack doesn't even extend to the suggested angle for the Lattitude.
But, today we have sun and I didn't have to fire up the gen. She will be all charged up and hopefully in float just as the sun sets. Then it starts all over again.

westbranch

and i thought my sunlight was severely limited by the mountains...  from Wiki... for 65* N

At this latitude the sun is visible for 22 hours, 2 minutes during the summer solstice and 3 hours, 35 minutes during the winter solstice.

morpho

ha...fat fingers...sorry... 55 degrees, not 65! Typing on a phone is pointless sometimes.
If I were at 65 degrees North I would be rapidly packing up and moving south...way south!

Estragon

morpho said:

ha...fat fingers...sorry... 55 degrees, not 65! Typing on a phone is pointless sometimes.
If I were at 65 degrees North I would be rapidly packing up and moving south...way south!

Even at 55deg those trees must cast some pretty long shadows about now.  Sun at about 15deg above horizon?  Would make the shadow nearly 4x as long as the height of the tree?

I once lived near 65N.  In the winter the sun is so low it's more like a twilight for the few hours it's out.  No trees to get in the way though.

morpho

Well Estragon, you are a far more hardy soul than I am. I am well past my comfort level this far north.
The sun is low on the horizon for sure and unfortunately/fortunately I don't have an over abundance of trees. Though the aspens are starting to make a go of it now that the cattle are not grazing this little section and I'm sure I'll have to cut some down at some point. For now, I am just happy to see something grow here.

Mike 870

Are you factoring in the cost of an extra charge controller or two, and wiring, combining and fusing?

morpho

Mike...that would be crazy talk!...factoring all the variables! HA!

Well, yes and no. I haven't run the numbers, but I know full well there are added costs.
But, I know I am currently dropping a bunch in gas and oil and parts and wear and tear on the generator.

Regarding more CC: I was wondering if it is possible to have the extra arrays on a switch that I can turn on when the extra power is needed - no different than I do with the generator - On a grey day I would only see 20-30 amps coming at me anyway so I don't know if I'd need another CC at all.

I have the whole thing throttled down so the batteries only see a max of 25 amps on a sunny day. (as per the Deka spec) so it may not be necessary to have the extra arrays on a switch. But I'd have to look into how it actually works.

Or...I just get rid of the fridge and the freezer and the TV...I would undoubtedly lose the wife in there somewhere.

HEY! Things are looking up! ...Just kidding dear. ;-)