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161
Solar / Re: Free Panels !
Last post by SparWeb -
At first glance it would seem like the string voltage would run up to about 350V if I put 10 panels in series.  Here's the label to see where that comes from.
20260215_213507_Label - Copy.jpg

Based on that, I might think that with higher voltage, there's less current, allowing for a cheaper wire run.  But that's the STC rating, and it doesn't seem to happen in real life.  The panels already on my garage roof have about the same specs, though different construction.  They usually don't go past 300V and in fact spend a lot of time between 240VDC and 290 VDC. Lower in the summer.

The upshot is that the current will be almost the same in AC or DC.  I won't save much money on wire, but to run DC I must dig up the old trench, probably damaging the existing wire, and lay down two new conduits of wire.  To run a separate trench causes me to circumnavigate a number of trees, making the dig much longer.  I'm not seeing the advantage.

The feed from the house to the barn is already 240VAC, 30A.  It's enough that these panels won't overload anything.  I'm not sure about back-feeding the 30A breaker with (up to) 25A, though.
163
Solar / Re: Free Panels !
Last post by bigrockcandymountain -
Would it make sense to run new lines and run high voltage DC to the house and put the inverter there?  Then you get to watch it.  A bit of digging, but cheap wire at least.  Then you could charge an EV right at the house with a string inverter / EV charger.  I know of at least one of those, and they look pretty slick. 
164
Solar / Re: Free Panels !
Last post by SparWeb -
Quote from: bigrockcandymountain – on
Well that's a huge win.  Will you do a ground mount?  That should cover the Ev charging and then some.

After the time it took to load up the truck, I'd recovered from the surprise a little, and I told Pierre that "when I get an EV, you've just fueled it up for ever."

I'm having so much fun figuring out how I want to set them up.  Right now I'm concentrating on the barn roof.

That would put these panels 200 feet away from the house, and over 400 feet from the utility pole.  That could cause a voltage RISE which is the opposite of voltage drop which we're more used to hearing about.  The panels will raise the voltage on the circuits in the barn, possibly too high and trigger the high voltage threshold shut-down.
166
Solar / Re: Free Panels !
Last post by SparWeb -
I first met Pierre almost 10 years ago when I started going to meetings of a group of RE enthusiasts, and started shooting my mouth off like I was doing on Fieldlines at the time.  Then this charismatic fellow got up and told me about HIS impressive system, and I sat down humbled but impressed. 
He's been a cheerleader for my projects for a long time, too.  Whereas I had several ideas who would be a good local installer for my solar panels, he knew the best, and he was right.  When I was switching to a new retailer for my electricity contract, he already knew the right ones.
167
Solar / Re: Free Panels !
Last post by MaryB -
WOW! I need friends like that LOL

3600 watts of panels is huge!
168
Solar / Free Panels !
Last post by SparWeb -
A good friend of mine has just gifted me something amazing.

20 Longi LR4 360W panels.

Wow.  I'm lucky to have the friends I do.

169
Electronics, Controllers & Monitoring / Cumulative Wind Energy
Last post by SparWeb -
Last December, I put in an energy meter to keep track of production from the wind turbine.
It's installed just below the battery charge controller, on a custom bracket I made, to give it a fairly nice look. 
The meter isn't measuring 2-way traffic on the battery, as it's designed to.  It's just measuring inputs from wind that charge the battery, only.  There's a a little "0%" digit in the upper corner that you just have to ignore because it's meaningless.

The meter looks like what it is: a little energy meter I bought off of Amazon.  It's from one of the very few sellers that doesn't seem fly-by-night, because they haven't changed their name 6 times in the past year.  The name DROK doesn't inspire much, but it's been selling on Amazon for a long time and I've got several of their meters installed here and there, and happy with them all.

Anyway, it's been counting the kilowatt-hours for two months and it's been a pretty constant 4 kWhr per day for the whole time, except one week with no wind (or sun = Dunkelflaute).
The trend won't hold up through the rest of the year - I've already had an energy meter tracking my wind production years ago, and it was obvious that summer has less wind than the winter.  A safe forecast is 1000 kWhr per year. Same as what I measured several years ago, which is also showing in this trend so far.
170
Solar / Re: My first year of solar
Last post by SparWeb -
Quote from: MaryB – on
Relay module I use https://www.morningstarcorp.com/products/relay-driver/ can monitor battery voltage then have 2 triggered events.
Thanks! That device looks very handy.  Seems to do the thing I am trying to do in my other gadget idea.


Quote from: MaryB – on
Main reason I installed this was to not be starting a generator when it was -20f! 
That's also what indoor plumbing was invented for :/
171
Solar / Re: My first year of solar
Last post by MaryB -
Quote from: SparWeb – on
Quote from: MaryB – on
My panels are fixed at 45 degrees

Are they arranged in 2 rows?  I've noticed some people with 2 rows of panels like I do, opt to have the upper row tilt up and down, depending on the season, but always leaving the lower row down.  When you think about it, it's obvious you don't want to tilt up a lower row because it will shadow the upper row.

2 rows fixed... I have plenty of solar year round, In the 10+ years since I put them in I have yet to use the outboard charger. Using a programmable relay module to monitor voltage and solid state relays I can drop the 2 inverters offline as needed and their loads drop back on grid. Keeps batteries happy and those loads have transfer switches on them so it is automatic. I run 2 2KW inverters(and a third 1kw that can feed the TV /audio system but I rarely have that one on). Typically see the inverters shut off 4 and 6 hours after sundown. I only run the fridge, 2 chest freezers, and some lighting(that is direct to the battery but LED so draw is minimal).  What I deem my critical loads that need to survive power outages.

Main reason I installed this was to not be starting a generator when it was -20f! 

Relay module I use https://www.morningstarcorp.com/products/relay-driver/ can monitor battery voltage then have 2 triggered events.
172
Solar / Re: My first year of solar
Last post by SparWeb -
Quote from: MaryB – on
My panels are fixed at 45 degrees

Are they arranged in 2 rows?  I've noticed some people with 2 rows of panels like I do, opt to have the upper row tilt up and down, depending on the season, but always leaving the lower row down.  When you think about it, it's obvious you don't want to tilt up a lower row because it will shadow the upper row.
173
Solar / Re: My first year of solar
Last post by SparWeb -
I came about 70kWhr away from finding out if the utility (or the retail company that bills me) cuts off the annual export rate if my annual production exceeds the imports.  I've wondered...  does it happen like that?
174
Solar / Re: My first year of solar
Last post by SparWeb -
A couple of reasons not to have tiltable panels on the garage roof.

Unfortunately, I am bound by a contract that does not have flexibility to reposition panels, unless I want to go back and re-negotiate with the utility company.  Not out of the question, but the thing's in balance now, so I'm fine.

Also, the racking the contractor used is simply not adjustable without replacing a lot of parts. 

Lastly, there's a a lot of snow blown-in and packed under these panels, now so I figure increasing the angle will increase the snow-load on the garage roof.  Even though I got a contractor to set up the panel arrangement, I did some back-of-the envelope math on the roof load and the (yeah yeah) cheap rafters on the garage.  Not a lot of margin, so having a higher snow load doesn't sound like a good idea.

That said...

I'm gonna get an EV soon.  That will throw off the precious balance.  Then, yeah, I'll need to do something!
175
Solar / Re: My first year of solar
Last post by Bruce S -
As you say, that's just about perfect!
Here in Missouri, the net-metering reset to zero on the 366th day of your start day, so anything left from the balance is freebie to the Mains provider.
The other cool part of the picture is catching the windmill on motion too.

Congrats!!
Bruce S
176
Solar / Re: My first year of solar
Last post by MaryB -
Quote from: SparWeb – on
Here's a picture of the finished PV panel installation.  They literally covered the whole garage roof.  There's barely a foot of space around them on all sides.

If you could angle them almost vertical in winter you would gain quite a bit... 18 degrees is great for summer production, not so much winter. My panels are fixed at 45 degrees, cuts both winter and summer production somewhat but evens out the rest of the year. Why 45? I am at 44.5 degrees north! 45 was easier to measure LOL
177
Solar / Re: My first year of solar
Last post by SparWeb -
Here's a picture of the finished PV panel installation.  They literally covered the whole garage roof.  There's barely a foot of space around them on all sides.
178
Solar / My first year of solar
Last post by SparWeb -
System spec: 6.5 kW of monocrystalline panels (Longi 440w) on my garage roof facing due south at 18 degrees from horizontal.  All PV managed by one Sol-Ark 12k hybrid inverter with grid-tie connection.
In years past, I consumed about 8100 kWhr per year +/- 300 kWhr.
This system was switched ON 19 December 2024 (yes, two days before winter solstice) so it's pretty easy to baseline my system's production whether you want to use the solstice or the new year.

In its first year, this system exported 5806 kWhr of energy to the grid, and my meter tracked a total import of energy of 5876 kWhr.  An almost perfect balance.  I have digital energy meters installed on the electrical panel of my house, which recorded 7858 kWhr used by the house during the year.  As the PV panels produced 7790 kWhr during the year, here is another near-perfect balance. Because only 5878 were imported from the grid, that means that PV supplied 1980 kWhr of the energy consumed by the house, or 25%.

This 25% reduction in consumption from the grid significantly reduced the costs of energy that I imported, but it gets better.  All of the energy I could export was paid with a premium rate.  Basically, when exporting to the grid, I am paid 3x the going rate for electricity I buy.  From May to September, my system was exporting much more than my needs (in addition to supplying much of my own needs). During this time I accumulated a credit on my bill which I have not yet used up (by the end of February I will).  What this all means is that my energy costs have gone from about 2500 dollars per year to nearly nothing.

I can't tell you all how pleased I am with how well the system has been performing.
179
Inverters & Grid Integration / Re: Interfacing wind turbines to the grid
Last post by bigrockcandymountain -
Quote from: SparWeb – on
Quote from: bigrockcandymountain – on
...my diversion load is a 500hz 12v signal that goes to a ssr and dumps the 48v battery voltage through an approx 10ohm resistor (water heater element) I assume the 48v comes out of the ssr at 500hz, not exactly as dc.

48v/10 ohms = 4.8 Amps
60v/10 ohms = 6.0 Amps

Hmm surely you'd dump more than that?  I think your WT is bigger than mine is, and I need a 2kW diversion load (and I admit mine turns out to be only 1.8kW).  It may not matter in your case if you're using your batteries most of the time.


Hmm I think it's 1 ohm or a bit more not 10 ohms.  I did the math in my head and that usually means it is wrong.   It dumps approx 2kw at 60v.  The math on that makes 1.8 ohms. 

I also have 3 resistors that dump straight off the 3 phase so when it makes over 2kw, i can still control things.  I don't have any logging on those, so I'm not sure what my peak production is.  4kw maybe.  Anything over 2kw and i start thinking about shutting down or half furling to limit power. 
180
Inverters & Grid Integration / Re: Interfacing wind turbines to the grid
Last post by MaryB -
Quote from: SparWeb – on
Quote from: bigrockcandymountain – on
What if all you did was add a very large capacitor (or a few of them) with a resistor in series to limit charge /discharge amps between positive and negative between the ssr and the micro inverter? Would it smooth the dc power enough that the micro would be happy? Would it store enough that when the mppt swept up it would drop a bit of amps and mimic a solar panel?

Funny you mentioned the SSR just when I was getting frustrated with designing my circuit with a MOSFET, and tonight I've been replacing it with a SSR.

I think I have the microcontroller signals figured out.  What's really bothering me now is that I've made some assumption about the inverter and I don't like the way things go bad if I am wrong.  I've been using Falstad's site to simulate this, and it suggests I will be blasting the 0.5 ohm power resistor with brief bursts of 90 amps.   Probably just something I have simulated wrong, but...

To your suggestion BRCM, yup, a big capacitor soaks up a lot of nuisance noise.  You just have to make sure it doesn't drown out the signal you want to measure.  Circuits that combine resistors and capacitors have a "time constant".  If the constant is long (in the electronics world 1 millisecond is long) then the time for the capacitor to charge up is longer than the time for a 1 kiloHertz signal to arrive, and you probably won't measure the signal.  On the other hand, if the capacitor is too small or ineffective, then the microcontroller is measuring pulses and it may pick up the pulse on the Hi during one reading, and on the Lo on the next.  From the microcontroller's perspective, the signal went from on to off, and in a sense, it would be right.  But in another sense it failed to detect what the power resistors are doing.  It missed the next Hi peak which has a different voltage than the last Hi peak, and that was the information it's looking for.  So there's a balance, when Goldilocks finds the right oatmeal.

Quote from: bigrockcandymountain – on
It sounds like a thread hijack when I read through it, but it kind of applies to sparweb's setup too.

Nah, you're forgiven

Most resistors have it buried somewhere in the spec sheet for a certain time it can handle an overload...

1.7 Pr 5 s for R < 2 Ω this example is 1.7 times the power rating for 5 seconds for a .5ohm 35watt

If you have a part number or maker/value used I can look up the spec....