Small Cabin

Small Cabin Forum
 - Forums - Register/Sign Up - Reply - Search - Statistics -

Small Cabin Forum / Off-Grid Living / General Solar Questions
<< . 1 . 2 . 3 . 4 . >>
Author Message
paulz
Member
# Posted: 17 Jul 2020 10:29
Reply 


Thanks Brett, I'll check out the calculator when I get home this weekend. Been wondering about that drop figure.

I was just about to start mounting and hookup when this new panel deal came along. Better wait and see what that is. I'm guessing grid tie systems are usable off grid, there was no mention of batteries though. Don't they provide power when the grid power shuts down?

ICC
Member
# Posted: 17 Jul 2020 13:00
Reply 


Quoting: paulz
I'm guessing grid tie systems are usable off grid, there was no mention of batteries though. Don't they provide power when the grid power shuts down?


The typical grid tie solar system has no batteries. When/if the grid goes down that house goes dark. A grid tie system can be built with batteries, like the Tesla powerwall system.

Nobadays
Member
# Posted: 17 Jul 2020 15:03
Reply 


Paul you must have been born at the end of a rainbow... you always find the pot of gold.

I won't pretend to know a lot about grid tie solar systems but I have been researching them for our house in Arizona.

Grid tie inverters generally require a 220vac feed to operate. They use the grid power as a reference to match phase/frequency and voltage for their output back to the grid. They are not Charge Controllers in the sense as we use off grid. They just invert the DC to the correct AC to feed back to the grid.

That said, in some cases it is possible to use another inverter tied to your battery bank to supply the power needed to operate the grid tie inverters. That is how they make these systems operate during power outages.

If I understand it correctly, solar panels - to - SCC - to - battery bank.... just like off-grid... then battery bank to inverter to create the 240vac/ this output wired to your grid-tie inverters - plus- battery bank to grid-tie inverters with this output to your load center.

I'm guessing the SCC to handle the volts/amps coming off that array will set you back a few pennies!

This is a good place to recommend a solar engineer draw you up a schematic and recommend equipment to make this all work.

The good thing is you likely have a lot of what you need.

ICC
Member
# Posted: 17 Jul 2020 17:20
Reply 


Quoting: Nobadays
The good thing is you likely have a lot of what you need.



Maybe, but the power companies are all very particular about the hardware that is used as the frequency and voltage must tightly match the power grid to prevent their equipment from being damaged by an unapproved "something". So no bargain basement hardware.

A few friends of mine who are on the grid and have grid tie solar solar panels have found that a good auto start generator with auto transfer switching was more cost effective than a bunch of batteries that mostly never get used. An exception is a friend in CA whose power company does much lower rates overnight. Their system can use low cost grid night power to charge when necessary. That system also switches to battery during the high cost daytime periods. I'm not sure what all special equipment was needed for that to work. It does apparently save $$ on the power bill.

paulz
Member
# Posted: 17 Jul 2020 18:44
Reply 


Thanks Guys.

Hmm, sounds like this could be a can of worms. Well I agreed to take it so we'll see what happens. Hopefully, at least if I can't use anything I can sell it to pay for my gas.

Wish I could take a look but don't have the address and apparently it's a gated community.

ICC
Member
# Posted: 17 Jul 2020 19:48
Reply 


I missed one of the previous posts. Those are Sunny Boy inverters. Good for grid tie only.

Panels good for both.

paulz
Member
# Posted: 17 Jul 2020 21:36
Reply 


Thanks ICC. Well that's good I can use the panels. If there are as many as claimed to be (you would need a lot for two inverters I suppose) it may be time to step up to serious battery power, like EV stuff. Then maybe a washing machine, dryer, welder..

But I'm getting ahead of myself. Got a week to wait.

Brettny
Member
# Posted: 18 Jul 2020 09:08
Reply 


Any large solar pannel like those for a grid tie system can be used off grid. There usualy just bigger and higher voltage. Your CC can take 150v input so you should be able to series connect about 3 of them.

So st roughly 130v input and maxing out the 40a controller your pushing 3.25a. This allows you to run longer distances with smaller wire...but you need very little shade on the pannels.

You will be able to run 200f with less than 3* drop and 14 gauge copper wire.

Nobadays
Member
# Posted: 18 Jul 2020 09:40
Reply 


If push comes to shove, at the very least you will have a couple of grid-tie inverters to sell, and possibly a few panels depending on how many there are. Your property is pretty limited for good solar locations.... though I love all those big trees!! If they give you everything you may get the transfer switch and other various boxes and... hopefully a bunch of wire!

As ICC and Brett said you can use the panels for sure.... how many you can series will be determined by the panel output which you won't know until you can flop one over and read the label on the back.

Something to consider because of all the shading you have is micro inverters.... rather than series strings. If shade falls on one of the panels in your string it cuts the output of that whole string. With micro inverters each panel is independent of the next, DC to AC is accomplished by the micro inverter at each panel then sent to a combiner box/load center. Enphase has a good PDF you can download to see how this is accomplished.

These are around $150 each but eliminates the charge controller.... you would still need some additional hardware. Wouldn't be cheap but with the panels in hand already.... maybe some to sell and inverters to sell... it's possible!

Hey I'm an optimist

Here is the link: Enphase PDF

Steve_S
Member
# Posted: 19 Jul 2020 10:18
Reply 


Just tossing this in here for consideration.
These Growatt All-In-Ones which have dual MPPT Solar Input, Inverter & can support Grid-Tie & Batteries are UL Listed. Growatt is a Tier-2 Company, not some value stuff shlock.

They are not crazy expensive, can have several connected to one battery bank (stackable) and have the communications, Management capabilities and more.

https://www.growatt-america.com/show-9-635.html

paulz
Member
# Posted: 19 Jul 2020 14:59 - Edited by: paulz
Reply 


I've been sent a photo of the panels, and the address, so was able to pull up an overhead on Google.

Look like big panels! And about 20-25 of them. Can you tell anything about them? Man am I glad someone other guys are going to pull them down. I'm supposed to pull the inverters. There must be cables running from structure to structure, I need to grab that too.
seaddri.JPG
seaddri.JPG
sead.JPG
sead.JPG


paulz
Member
# Posted: 25 Jul 2020 18:08
Reply 


Yesterday was the big haul. Here's the bounty. 29 panels - LG260S1C-G3. They are big, about 3x5. 260w I think. Also got 3 boxes that were on the side of the house, 2 are Sunny Boy, one has to be 150 lbs. heavy. Don't have their numbers,one at least is an inverter. And all the racking, a bunch of heavy wiring...

Hope I can use it...
IMG_20200725_125225..jpg
IMG_20200725_125225..jpg
IMG_20200725_125214..jpg
IMG_20200725_125214..jpg
IMG_20200725_125106..jpg
IMG_20200725_125106..jpg


paulz
Member
# Posted: 25 Jul 2020 19:00 - Edited by: paulz
Reply 


I found a photo of the heavy box online (only 97lbs., guess I'm just old..) It's a 'battery inverter' and can apparently be used off grid. Have a look at the link and tell me what this thing does.

https://www.mg-solar-shop.com/solar-inverter/sma-solar-inverter/sma-sunny-island-si/s ma-sunny-island-si-4-4-m-12-battery-inverter.html
IMG_20200725_125115..jpg
IMG_20200725_125115..jpg


paulz
Member
# Posted: 25 Jul 2020 20:03
Reply 


The other Sunny Boy box is this

https://www.foreverpureplace.com/Sunny-Boy-2500HFUS-Single-Phase-Grid-Tied-Inverter-p /sb-2500hfus-30.htm

Grid tie only, apparently
IMG_20200725_125201..jpg
IMG_20200725_125201..jpg


FishHog
Member
# Posted: 26 Jul 2020 09:04
Reply 


That is a good find Paul.

Nobadays
Member
# Posted: 26 Jul 2020 09:11
Reply 


What a score! Looks like the big inverter can be used off-grid.... 3000 watt and able to charge Lithium. Looks like you need to download the manuals and do some studying! We can provide for all our power needs and we have an electric fridge, freezer, washer and of course lights and ceiling fan.... with 6, 245 watt panels. We did just added 3 more mainly for bright cloudy days and winter when the 6 on the roof are snowed over. All that to say you have a bucket load of panels to sell or barter with as well.... way to go!

paulz
Member
# Posted: 26 Jul 2020 09:43 - Edited by: paulz
Reply 


Thanks guys. Yeah I found an online manual for the big inverter, have a lot to learn. I have time though, the panels will go on the roof of my shop, which is 40x60, and right now is only about 90% sheathed and no membrane. So it looks like solar will by my winter focus this year. Guess maybe I should start looking for a Chevy Volt battery.

Unimportant back story: The owner of the house was there, along with a 4 man crew, and I got the story. The previous owner had the system installed, and was leasing it for $250 a month. The new owner, a wealthy developer, only uses it for a weekend getaway and didn't want to pay the $250. The solar company got paid off (maybe in escrow) and that ended that. He's paying about $50 a month for grid power now.

Here's the odd part: The house is right on the Pacific coast, so apparently the installers thought the ocean was west. But it's not, the house is on a cove. So the panels ended up facing mostly north!

So on these grid systems, is he supposed to get back his $250 a month by feeding power into the grid? Not much point in it otherwise since there is no storage..

ICC
Member
# Posted: 26 Jul 2020 14:13
Reply 


Quoting: paulz
So on these grid systems, is he supposed to get back his $250 a month by feeding power into the grid?


Short answer, yes.

Leases can vary in their terms but are usually a bad idea, especially on a second home. The lease company owns the equipment and receives all the tax credits, etc. The lease normally has an annual % increase in cost. If you take a vacation you still pay the full amount even if everything is turned off. You are allowed to use up to a certain kWh of power and can usually bank unused prtions on an annual basis. If you buy more efficent appliances and actually use less power yo still pay the lease ccompany the same amount. There are also PPA's which are as bad, maybe worse.

Neither give any battery backup as a rule as that costs more. Having leased or PPA solar often makes a house harder to sell, even though the lease or PPA salesperson will tell you otherwise.

If one owns their own home it is usually possible to get a loan and own what is installed and save lots of money in the long run. But not everyone has enough equity in the home.


I'd say your panels are great and unless you want to become grid-tied sell the Sunny Boy hardware if you can. As for that inverter it appears on a quick look that it might be for 498 volt and higher battery systems.


There are alsp PPA's which are even worse, IMO.

Brettny
Member
# Posted: 27 Jul 2020 07:26
Reply 


Yes that's how the lease systems work.

When I looked at it for my house I would break even so basically was betting on the fact that electric prices would rise , we didnt have snow/ice that would stick to the pannels or a very cloudy/rainy spring/fall. We dont have pannels on our house. This is also baring the fact that it could be seen as a bad thing in a home sale.

paulz
Member
# Posted: 2 Aug 2020 22:14
Reply 


There is an ad in my area for new solar equipment, I think they bought it all at a bankruptcy auction last year. Among the items are Midnite Solar Classic 250 charge controllers. Anybody got anything to say about them? Thinking about getting one.

Here is the list of stuff


We are selling Brand New Off or On Grid Solar systems or individual components at a fraction of their retail price.
Please see the items list below

-SMA SUNNY ISLAND INVERTER, MODEL SI6048-US-10 INVERTER, MAX CONTINUOUS OUTPUT POWER 5750W, MAX CONTINUOUS OUTPUT CURRENT 47.9A RMS, OUTPUT POWER FACTOR RANGE OF INPUT OPERATING VOLTAGE 80-150V AC $2200 each

-TALESUN PHOTOVOLTAIC 270 WATT SOLAR PANELS TYPE TP660P-270W $150 each

-MIDNITE SOLAR CLASSIC 250 MPPT CHARGE CONTROLLERS $ 440 each

-MIDNIGHT SOLAR MNPV6-250 Solar Combiner box $70 each

-GNB TUBULAR LMX 24 CELL 48 VOLT BATTERIES MODEL M1902409013B $3500 each

Specs on the Midnite 250

250 operating voltage
Max current out: 63 amps
ETL listed to UL1741 and CSA
Type 1 environmental rating
Terminals are rated for 75 C
Exclusive HyperVOC extends VOC limits
12-72V battery
Built in DC-GFP and Arc Fault
Detector
Solar, wind and hydro MPPT modes

Nobadays
Member
# Posted: 2 Aug 2020 23:13
Reply 


Good charge controller and a good price... same with the combiner box.

paulz
Member
# Posted: 3 Aug 2020 10:18
Reply 


Thanks Nobs. I finally took a look at the DIY solar forum you mentioned. Wow, 6 pages of threads on a Midnite Classic search! The first thread was an Amazon link for the 250 at about the same price with free shipping. I'll be reading all the relevant threads in the next couple days but in the mean time if you care to comment on:

Are these an up to date tech controller or an older style being sold at reduced prices?

Looks like there may be more than one 250, a 250SL for one?

I see they are not lithium controllers but many use them with lithium and a BMS. Is that pretty much standard practice?

Is the combiner box something most folks use?

I need to do the math on how many of the 29 panels (LG260S1C-G3) I have it could handle, or if there is something larger I should consider. I'd like to use all the panels in different directions to capture what sunlight I get.

You mentioned micro inverters, that's something I need to read up on too. I didn't realize the shade/serial wiring issue, good point. Sounds like I would need a lot of them at $150 a pop though.

My panel specs:
Maximum power at STC (Pmax) 260
MPP voltage (Vmpp) 31.2
MPP current (Impp) 8.35Open
circuit voltage (Voc) 38.6
Short circuit current (Isc) 8.82
Module efficiency (%) 15.9
Operating temperature (°C) -40 ~ +90
Maximum system voltage (V) 1000 (IEC), 600
Maximum series fuse rating (A) 15
Power tolerance (%) 0 ~ +3

ICC
Member
# Posted: 3 Aug 2020 15:00 - Edited by: ICC
Reply 


Micro inverters are only used for a grid tie system where the power goes directly from the PV panels to the grid. Micro inverters take the PV panel DC and converter to AC. Each panel has its own. Makes it wasy to handle installations where some panels may get shaded for some of the day and the panels can be faced any-which-way to the sun.

Re the Midnite charge controllers... there have been fake (counterfeit, copycat, whatever term you like) Outback FM series and Midnite Classic series controllers coming out of China for 5 or 6 years, maybe longer.

You need a combiner box if you are connecting panels in parallel, including parallel connections of series strings. You also need to fuse or use circuit breakers at that combiner box if you have more than two panels (or series strings) connected in parallel. That is a safety thing and is needed to meet NEC.

I don't like fuses except for the smallest of systems.

I like the Midnite circuit breakers because MidNite circuit breakers are rated for 100% continuous duty. MidNite's breakers are rated to break the full rated load at the rated voltage repeatedly, with NO DAMAGE. THose ratings are only NEC valid when their breakers are mounted in one of their boxes or cabinets as that is how thay were tested.

MidNite has a panel string calculator that you will find invaluable when trying to configure parallel and series panel arrays. It will take cold weather into account if you enter the data requested correctly. http://www.midnitesolar.com/sizingTool/

Midnite also has the best surge protectors (SPD). I use them at the panels, charge controllers, inverters and service entrance to the ranch power center. They have led's that when illuminated tell you they are still functional. Lightning strikes do wear them out. Three different models for different voltage ranges. Don't build a system without them.

IF the lithium battery has a built in BMS there should be no problem with a Classic. If the lithium battery has NOT got a built-in BMS then an external BMS MUST be used. That has to be tailored to the batteries/cells.

ICC
Member
# Posted: 3 Aug 2020 15:16 - Edited by: ICC
Reply 


One more thing. I prefer using the same brand for the charge controller, inverter and monitoring equipmemnt. That is one reason I lean towards Outback or Schneider. Everything can be tied together and controlled by one master unit or on a web connected PC, phone, tablet, whatever.

I do like the MidNite stuff for its engineering and product quality. Midnite does sell some prewired sets using Schneider, Magnum or Samlex inverters, maybe others. SMA I think. I have not looked recently or very closely at them. Possibly they have mastered how to interconnect for controlling, setting and monitoring as a system. I have no idea.

Nobadays
Member
# Posted: 3 Aug 2020 16:21
Reply 


Quoting: ICC
Micro inverters are only used for a grid tie system where the power goes directly from the PV panels to the grid. Micro inverters take the PV panel DC and converter to AC.


This isn't entirely correct. They are "PRIMARILY " used on grid-tie applications but there are some used in off grid applications as well. They work both as micro inverters and can meet code where rooftop mounting requires rapid Shutdown. My solar engineer was going to use micro inverters for our application before his research turned up the Fire Raptors we ended up using for rapid Shutdown. Micro inverters really shine in areas with lots of shading issues.... why I mentioned them to Paul.

Here again is the link to the Enphase PDF for off-grid use of micro inverters.

ICC
Member
# Posted: 3 Aug 2020 17:42
Reply 


Tech never stands still, but often I do

paulz
Member
# Posted: 4 Aug 2020 10:11
Reply 


Man this solar education never ends! I played with the Midnite calculator. No matter how I enter the parallel/series fields, to use all 30 of my panels would need 3 Classic 250s. Are there SCCs made large enough to handle all my panels?

Nobs, I'm glad you brought up my shade situation again. Shade will only kill off the panels wire in series, another bank in parallel still in the sun won't be affected, right? If I had say 3 sets of 10 series panels, one east, one south, one west, in parallel, and only one was getting sun at a time, in theory one Classic 250 would do?

Did a little reading on the micro inverters. So what happens when the AC leaves each panel? How does it tie together, what box serves as a charge controller for the batteries? Is this a more recent technology that may become less expensive in the future?

Searched but didn't find any info on spotting fake Midnite Classics. Here is the ad for the sale near me:

https://sfbay.craigslist.org/sfc/for/d/san-francisco-off-on-grid-solar-panels/7170245 057.html

Nobadays
Member
# Posted: 4 Aug 2020 11:16
Reply 


If you want to use all 30 panels it's very likely you will need 2-3 SCCs .... a lot depends on how you wire them, how many in series/parallel. Regardless you have a lot of potential power there.

I don't want to imply I'm any kind of solar expert.... I just read a lot and am.... very much!.... still learning! Here is my take.

Yes you can aim a string this way and another that way, and yes this would "likely" reduce the amount of voltage/amps being delivered to your SCC.... but that is not how most engineers/solar enthusiasts plan a system. In general terms you have to plan for the maximum possible input, anything less and you could potentially "fry" some very expensive equipment.... or even burn your place down.

Think about your thoughts on strings of 10 in series.... those have a VOC of 38.6 so 10 in series 386vdc! That is going to require a pretty large SCC! Even at the VMP you are looking at 312vdc. Certainly SCCs out there to handle that kind of power but my understanding... and I could be wrong... is you want to balance your voltage and amperage. The 3 strings of 10 you mentioned would deliver around 312vdc in parallel but only about 25amps. If you look for a charge controller in say the 30-40amp range, you will find input voltage around 150vdc. Certainly look around but SCCs seem to make a big jump, either they are around that 150vdc input, or they jump up to 600vdc... And now your back to why you will likely need 2-3 SCCs.

All this said.... before you start buying charge controllers and batteries, you really need to back up and determine how much solar power you need! The folks at NAWS have a great calculator HERE. Go wild! Add everything you think you might use. Once done, then you will have a baseline to start from to build a system that will meet your needs.

Just for reference, we have 2,220 watts of PV, on a 48v system with 12kw of lithium storage. We use a 10cuft electric fridge, a 4cuft chest freezer, satellite internet, we watch a couple hours of TV in the evening (streaming), toaster, microwave, of course lights and also a window fan when it's warm in the loft. We can easily go 2 days without sun and can squeak 3 days if we cut back and conserve (no tv, limited internet). Oh, and most days we never drop below 46v... so using about 20% of our storage capacity and are floating by 11:30 - noon.

Do you really need 7,500 watts of PV? How big of battery bank would you need to store this potential power? Take a little time and start from the beginning.... I know, I know I just wanted to slap some panels up too... it will pay off to do the planning!

ICC
Member
# Posted: 4 Aug 2020 12:52
Reply 


Schneider makes 600 volt charge controllers. 600 volt DC max input from the array, 80 amps I think.

paulz
Member
# Posted: 5 Aug 2020 10:40 - Edited by: paulz
Reply 


Thanks guys. Neat usage calculator Nobs. But how much do I need? If I were to move my shop completely out here that's welders, lathe, mill, tire machines, compressors, but only one or two running at a time... If we could live here full time (a dream that is slowly becoming a potential reality) that means washer and dryer, microwave, TV.. I just don't know at this point. But I enjoy looking for deals that pop up locally (being close to a large wealthy metropolitan area) and also use it as a learning tool (well that and you guys!).

I won't be putting a single panel up for months, still working on the roof they are going on. Speaking of which, I was up there most of the day yesterday. During the course of the day, probably 2-3 hours total time the roof had full sun, some in the late morning and some in late afternoon. And that's mid-summer. In a month or two, when the sun gets lower I'll be lucky to get an hour, and non after that. No other place on my lot any better. So this whole project may prove fruitless.

But I have the panels, might as well try. The 10 panels sets I mentioned was just an example, could be 5 panels in series, 6 parallel sets. Point being the more parallel sets the lass chance one shady panel will kill the others. With the 4 35w HF panels I have now, often just one is is shaded by a tree at a given time.

So the only thing pressing at the moment is the stuff that comes up for sale, and weighing weather it's usable for me or a waste of money. The Schneider 600v controller ICC mentioned is $1,200-1,500, or about 3 of the Midnite Classic 250s. Which would be better for me?

How much battery? Good point. If I wait around long enough, somebody will probably give me a Volt or Leaf! Again hard to say without knowing how many days we'll stay at the cabin and how much charging power we'll have both when we are here and when away.

I really appreciate you guys bearing with me in my unorthodox way of approaching this. If my place was basking in sunlight and I had a good handle on my future needs things would be different. I don't mind blowing a couple grand on a potential bust, more than that would get disappointing.

<< . 1 . 2 . 3 . 4 . >>
Your reply
Bold Style  Italic Style  Underlined Style  Thumbnail Image Link  Large Image Link  URL Link           :) ;) :-( :confused: More smilies...

» Username  » Password 
Only registered users can post here. Please enter your login/password details before posting a message, or register here first.