Osceola Iowa, Solar Backup Generator project

[eyeinthesky]

   This is my new Solar Backup Generator project.  I got tired of looking at specs for systems sold on the market that talk up the capabilities of their systems like "2000 watt, can power a microwave and refrigerator at the same time!".  Great, so it can power it up for 5 minutes, and take a week to recharge... what a deal!  So, I decided to build my own with an actual purpose in mind .

   2000w Zantrex Pure Sine inverter
   500ah LiFePO4 12v battery bank (20 X 100ah 5000 cycle cells)
   720w 12v solar array (6 X 120w panels)
   MidNite Classic 150 Charge Controller

   My main residence is powered with an Enphase grid tied system (Self installed), 6.45kw via 30 roof mounted 235w 24v Sharp panels.  I also use the MidNite DISCO box for that system, can't beat it!  System provides 85% of yearly usage.  The backup system will also be used to power an emergency room in the house, and will also be used to power a freezer.  Future plans include using the AUX1 relay of the Classic to turn on a small backup grid tied charger when SOC is low, and shut it down when above 25%.  Also an auto transfer switch for other essential loads (furnace fan, fridge, etc.).  Anyhow, it was nice to see it light up, but, now I need some sunlight...

>> Bill

[Cniemand]

Nice, Bill.

What brand cells are those? Blue? Are they CALBs? I know CALB has a newer one after the SE & CA series which are metal cases with a plastic wrap of sorts, but those are mainly designed to situations where you need fast discharge rates.

As for 5000 cycle count Batteries. Are you suggesting that you designed your system with the intent of staying within 70%DOD to achieve those 5000 cycles?

100%DOD = 2000
80%DOD = 3000
70%DOD = 5000

Are the numbers generally tossed around for Lithium Iron Phosphate chemistry cells. It is the numbers stated by CALB and the research done by EVTV for their electric vehicle builds.

Cloud

[eyeinthesky]

Nice, Bill.

What brand cells are those? Blue? Are they CALBs? I know CALB has a newer one after the SE & CA series which are metal cases with a plastic wrap of sorts, but those are mainly designed to situations where you need fast discharge rates.

As for 5000 cycle count Batteries. Are you suggesting that you designed your system with the intent of staying within 70%DOD to achieve those 5000 cycles?

100%DOD = 2000
80%DOD = 3000
70%DOD = 5000

Are the numbers generally tossed around for Lithium Iron Phosphate chemistry cells. It is the numbers stated by CALB and the research done by EVTV for their electric vehicle builds.

Cloud

Thanks Cniemand for your comments!

   The brand cells seem to be Energetech, purchased from electriccarpartscompany.com, but have since disappeared from their website.  They had to be directly imported in.  The CALBs all showed as 2000 cycle, which is still great, but these batteries were rated 5000 at 80%DOD.  The part number was LY-100AH, and they in fact are metal cases with a blue plastic wrap.  I purchased 24, used 20 for this generator, and 4 extra to make a 100AH 12v portable backup battery.  They are still a lightweight portable battery bank, and allows me to be able to easily relocate the generator if need be, or if I want to use the system for a HAM radio field day or something.  The Aquion batteries sure look nice, but they don't appear to be very portable .

   I am still testing this setup, right now it is supplying a light load of 2.6A minimum, which powers my HAM radio equipment, and some small load items.  It is winter, and this year has been the worst year so far for solar, even my main system is doing poorly this year.  I will soon be adding a little more load as soon as I update the wiring to the "Green room".  During the other 3 seasons, I will be adding additional loads as needed to take advantage of its capabilities.  I will also add the auto transfer switch to power essential loads in the case of grid outages, that can be manually cycled in the case of extended outages (ice storms, occasional tornados, squirrels with nothing better to do than to chew on power wires, etc).

   Not pictured is the small 10A charger that the classic will turn on at 25% SOC, and shut down at 35% SOC to keep the bank from draining low, and also for now the MiniBMS is active to shut down at a dangerous level if all else were to fail.  I even have backups for my backup .  The system should automatically charge from the grid source at 25% (still 85% solar), and the classic should charge the bank up to a max of about 85 - 90% at this point.  I may still play with these settings after more testing and confidence is gained in the equipment and battery monitoring.

>> Bill

[Cniemand]

Hey, Bill.

It has been a crap weather for solar this winter season. The previous couple years on this mountain in Colorado it has been beautiful. Very seldom would we have much for clouds. What typically would occurr is that we would get a blizzard, then it would pass, only to leave an hour or two left in the day to FLOAT the lithiums. I've managed to live easily on 100% solar as I haven't a backup genset.

This year I have had to keep more of an eye out of what I want to use up in the bank before going into a snow event the next day to make sure all is well.

You are a grid-tie setup?

Cloud

[Westbranch]

Cloud, sounds like you are in line for an addition to your array, 4 x 250PV... I was like you  but the winter blahs have hit.... we aren't getting the usual cold, sunny winters now, just week after week of cloudy weather up here in BC... and far less snow... good sun maybe every 4 - 6 days...

cheers, 6 more shortening days , then we are past the HUMP! 

[Cniemand]

I already have 8 -250 , but I guess I wouldn't object to eventually getting another set. ;-)  Actually, I think simply doubling the LFP bank to 32 cells rather than 16 would mitigate any concerns about weather. We manage to do quite well with a 5 kWh pack. A 10 would be a dream... or well a ten? Ha!

Now if I can find where I misplaced that $2500 USD to implement it....

Cloud

[Cniemand]

WB, Have you noted a substantial increase in Fuel Costs/increased gen run times this year over those past?

[Westbranch]

fuel price yes, but going down now, gen run time, not really as I re arranged my arrays so I get 1680W onto the main bank, did very well till the grey skies hit in late Oct, then I started to use the gen about once a week, just in case there s a long stretch of darkness...Sat internet is running 24/7 but having connection issues with MM, new control board to put in arrived yesterday,  . 

We have been in town mostly since end of Nov..., Dr. and social commitments, etc.

road snowed in last week... Skidoo time now I guess...Christmas travel next 2 weeks...

[eyeinthesky]

You are a grid-tie setup?

Cloud,

   Yes, my main system is grid-tie.  I live in town, and my house kind of stands out, as I believe that there are only 2 houses in the area that have solar, and mine being the only one in town.  I walked in on an awesome rebate pilot program with the local utility.  I chose to go with an energy efficiency program that allowed me to take advantage of insulation and home sealing rebates, and qualify for a higher rebate rate for the solar.  I chose the enphase solar microinverter design, and designed and installed the system myself saving a huge amount on installation charges.  With the enphase system, each panel has its own microinverter, so even if there is a panel failure, or shading, it will not affect the entire array.  I have 30 Sharp 235w panels attached to rails that are attached directly to the roof.  The inverters have a nameplate rating of 215w for a total 6.45kw.
   Since I self-installed the system, received the 30% federal rebate, the utility rebate, and the State rebate, I came out ahead on the deal, and that was prior to the system savings.  I also have a net metering arrangement, which banks the over production at full rate.  Last year I went 9 months only paying about $10 a month to the utility for minimum billing, cheaper than batteries!  Of course, the downfall of grid tie, if the grid is down, so is the solar system.  This is why I decided to build the backup generator with 6 120w panels for emergency power when the grid is down.
   I decided to make 1 room in our house run completely off this solar generator to make use of the resource, but still provide a standby means of power.  I'm not done with it yet, but this room will be extra insulated, and will be our emergency "goto" room for weather emergencies, or an extended grid outage, as we all know how safe the power grid is...  If things look to be even more extended, I can also repurpose a few more panels to the solar generator setup if need be.  I will also have the auto transfer switch set to run an essential loads circuit for the sump pump, refrigerator, freezer, and furnace fan for short term outages like a UPS. 
   I also have in the design a hand crank PMA that can also be driven by an exercise bike to provide some charging if things get really rough .  I bought a low wind PMA many years ago to play with, but never did anything with it, as unfortunately my house is not optimized for wind. 
   Funny, I was teasing my wife one day about tying a wind turbine to our chimney, and she said "absolutely not"!  I said "then I'm installing solar panels", and she said "I can deal with that".  She had no idea!  I ran with it.  She got nervous when the pallet of panels got delivered off the truck...  After now about 2 1/2 years later, she is much happier about it .

>> Bill

[dgd]

Bill,

So a 6Kw grid tie system  and now a battery and PV separate backup system in case the grid fails and you have 6kw PVs doing nothing. And  this backup now powers one room

You don't make a profit from the grid tie, ie an income from the power company? I assume not as you say you still pay a token $10 per month.

One of the more common additions to many GT systems here in New Zealand is to retro fit
a battery to provide an 'essential service' power in the event of a grid failure.
Those Tesla battery packs seem to be very popular for this as near all the GT inverters can accomodate them and have software to manage essential loads.
Certainly a lot cheaper than creating a whole new battery/pv controller/inverter/PV system

dgd

[Cniemand]

@ WB :

Indeed! It is definitely "Skidoo" time. I have this big 3 acre front yard with no obstructions and a tiny Cabin/Home towards the back. Plenty of room to get a little zippy with the tracks. ;-)

@ Bill :

Good stuff! I am off-grid so no rebates for me, however, still saved heaps of money by doing it DIY. You installed the panels, rails, wired it all to the Main panel, then simply paid an electrician to once it over and hook it to the mains so the Utility would write it off? I'm sure that saved you 10K.

The idea of micro-inverters is a neat one. Certainly useful when you are in the city with shading issues derived from mature trees and congested neighborhoods. My skies are wide and open so could omit them for just a single.

@ DGD :

What is the average solar insolation for Auckland? I was out there in 2001 for a short bit. Lovely place. I imagine it's akin to the higher latitudes in the US.

[eyeinthesky]

So a 6Kw grid tie system  and now a battery and PV separate backup system in case the grid fails and you have 6kw PVs doing nothing. And  this backup now powers one room

You don't make a profit from the grid tie, ie an income from the power company? I assume not as you say you still pay a token $10 per month.

dgd,

   Yes, it appears at first to not make too much sense, but worked out well in my circumstance.  Basically, by taking advantage of the utility rebate during the short timeframe that it was offered, it for the most part, paid for about 80% of my total cost.  Then the US currently offers 30% return on federal taxes, and the State offered an additional 15%... That came out to be about a 125% return.  Best of all, I own it, if I were to decide to move, it comes with me.  The $10 a month is charged to all grid connected customers to pay for distribution costs, I'm good with that.  Basically the utility is like a battery of sorts this way, I produce and push power to the grid during the day, then use power from the grid at night and cloudy days.  Although this arrangement is not completely "off grid", it was still a no-brainer to take advantage of!

   The backup unit was my "project".  I still had enough roof railing to add the 6 additional panels to the deck roof left over.  I was going to install 2 120w 12v panels, then bought 2 more, then again 2 more to make it complete.  I had a Xantrex C35 controller to originally play with, but decided to do it right and go with the Classic 150 since I was going to need a bigger controller.  Even though MidNite seems to be scared of LiFePo4 batteries, and seem to not want to be liable in any way by adding a LiFepo4 charge profile, other reviews showed that the Classic was fully configurable, and with the WBjr, it can be used accurately.  I decided to use the LiFePo4 cells because they are 1/3 the weight and size which makes the unit portable.

   I attached a picture of my main solar array.  This picture was taken just after the original install, and before we replaced the siding on the house.  The deck roof at the end is where I added the additional 6 12v panels for the solar generator.  Also, the big tree that you see to the right over the garage, is no longer there .

>> Bill

[Cniemand]

Beautiful array, Bill.

I would venture that Midnite Solar is not so much afraid of Lithium but rather waiting on a consensus of actual Lithium users to get the profiles squared away and see the commonality. Right now there is this back and forth about Bottom Balance vs Top Balancing.

[ralph day]

Bill,that vintage truck...is it an International?

ralph

[eyeinthesky]

Bill,that vintage truck...is it an International?

Yes it is, and its for sale.  Its the neighbors truck, and actually can't wait till its sold, as it is kind of in the way when I have to remove snow from the panels during winter.  I always have to work around it with the 35' pole.  Other than that, it is a neat truck!  It has a braking problem, but who needs those?

>> Bill