If you've used my Excel sheet for sizing solar power

[papaof2]

You need to download the latest version. Several oversights in the process of moving from 50% DOD as the default battery parameter have been corrected and some of the notes have been improved. Also a suggestion about powering certain items while charging the battery bank from a generator. Some of the changes will make the spreadsheet more accurate in predicting runtime for known loads - more accuracy is always better, even if the number of hours is smaller. At least you won't be surprised when the lights go out the second time...

www.jecarter.us/files/My-Solar-Generator.xls

[papaof2]

If you downloaded the spreadsheet before 6:40AM EDT 8 July, you need to go back for the even newer and more improved version. This one won't barf if you put 2000 watts of solar panels on your 12 volt, 420AH battery bank. It also flags things if you don't have enough battery bank to run the selected load for at least 24 hours. If the battery bank doesn't support 24 hours, a 20 hour outage followed by a rainy day will put you in the dark. You can still use the spreadsheet for a "Wait until daylight" backup system, but now highlights the cells that don't show 24 hours of capacity at the specified load. copy and paste

www.jecarter.us/files/My-Solar-Generator.xls

[techsar]

Going to have to go through it a bit, but it looks like it has potential

Over 740 Ah @ 48vdc (nom) LiFePo4 kind of skews things. Hopefully it won't make the spreadsheet barf! lol

[papaof2]

There's a separate spreadsheet for higher voltages. It's not as detailed as the original 12 volt spreadsheet but it is functionally similar - although not updated with all the bells and whistles of the original (copy and paste):
jecarter.us/files/My-Solar-Generator-Voltage-Set.xls

You probably would be using the "Charging With Load" page the most. I tend to follow "rabbit trails" (called "learned digressions" by a professor I knew) when designing spreadsheets (and writing stories) because "It's just a few more minutes" to put another idea on paper. Then whichever part(s) of that idea is(are) most useful to me will get most of my attention over time.

When I have a day or two that I feel like tweaking numbers, I might get the higher voltages spreadsheet updated. My last check of cells in use and blank cells in the 12 volt spreadsheet's total column area came up with 505 cells with numbers and 991 cells that were blank or had overflow content in them from an adjacent cell, so updating just that one page is a major undertaking - and then there's testing :-( At least Excel has a function for counting used and empty cells so I know how big the update job will be.

You also could multiply the AH by 4 and use the 12 volt spreadsheet - the power and hours should work out the same: 250AH at 48 volts is the same amount of stored power as 1000AH at 12 volts. The higher voltage system is a bit more efficient as its losses through the cabling is likely to be less - some folks have a real problem with the price of #2 and larger wire... The biggest wire in my backup system is the #4 between the batteries and the #4 to the main breaker. The 2000 watt pure sine wave inverter came with two red cables and two black cables so they did the "just big enough for the load" wiring that way. Parallel cables are 3 sizes bigger in capacity than the single cable would be: two #10 equals a #7, for example. But I know the maximum wattage of the loads the system will have, the efficiency of the inverter and the lengths of the wiring involved so #4 is adequate where it's used. I have a couple of 4 foot #2 cables if I need to move the inverter from its place on the outside of rack at the end of the shelf which has the batteries. It looks odd to some people but the wiring is short and the inverter has excellent ventilation. It's seen intermittent use for 5 years and still works every time the breaker is turned on. Sold by reliablepower on ebay and the case matches the current WZRELB inverters - but no name on the case. Doesn't matter when it just keeps working and I have a spare of the same inverter ;-)

I'm functional at the moment because the Rx pain med I took about an hour ago is reaching it's full relief level. On a good day, I'm almost where I was several years ago, just a lot more cautious about what I attempt to do and how long I spend doing it, such as I can walk longer than I can stand and work in one place and there are few seats in the house that provide proper support. I've been dealing with chronic (and occasionally debilitating) back pain for a couple of years: lots of epidural injections, MRI, SI joint fusion surgery and my current pain management regiment includes a 7 day patch (continuous release pain med) plus 75 tablets a month of Norco (5/325 hydrocodone / acetaminophen) for "breakthrough" pain that the continuous release pain med from the patch doesn't always cover. And the option of adjusting the Norco as I see the need because I've been keeping a pain + med diary for more than a year with multiple daily entries of what hurts, what might have influenced that (rainy weather is a factor as are too many trips up/down stairs and too much time standing on concrete or ceramic tile floors - 15 minutes walking slowly (1.6MPH) on a treadmill is not as bad as 15 minutes standing on a concrete floor while working on something) and how much pain med I needed when. And there are the semi-regular urine tests the doctor's office does to monitor the level of Rx pain meds in my system. I think the trigger for the patch was two events earlier this year when there was somewhere I needed to be but I hurt too much to walk to and sit up in a vehicle long enough to get there. I'm almost back to the level of driving again, just need to have the bottle of Norco with me so I can pull off and take one and curl up on the "almost a seat" behind the front seats until the pain drops enough for me to function again. Gettin' old ain't fer sissies ;-)

[papaof2]

The spreadsheet has been updated again. There's a cell at the top right with the "last update" date in red.

Updates are sporadic but usually at least once a quarter.

[techsar]

Just re-reading...as far as the price of larger wire, look for used but decent condition welding cable. That's how I got 4/0 cables for between the main DC breakers and the inverters. Even under large loads there is no appreciable voltage drop or heating. Half inch copper pipe works well for fabricating terminal ends. Aerospace and .mil would have a hissy but I crimped then soldered.

Thanks for the update!

[papaof2]

Creative folks look for "What will do the job?" not "What's designed for the purpose?"
That's sort of my outlook - certain things need to be done but I don't have the EXACT tool or equipment to do that.
However, I can probably... (and you put the creative answer here).

The batter half had a two-hooked shepherd's crook for holding two bird feeders. It was just a few inches shy of being tall enough that the squirrels couldn't jump up past the "no-climb" device. Solution: cut the rod and then extend it with welded-on pieces. I had no round stock the right size - but I did have some angle stock that fit the rod nicely. So I cut the rod, clamped on two pieces of angle stock that were long enough to extend the top of the crook where I wanted it and welded the angle stock in place. Chipped the weld then used a wire brush. Gave it two coats of no-rust paint and 10+ years later it's still together.

I'd like to have a PM-modified CS130 alternator (85+ amps) but I have the original version and while it doesn't produce as much power or works as efficiently as the PM version, it could keep the batteries of the solar-charged backup system charged when there is no sun - and it's more efficient to be using the alternator and its three-phase rectified DC than to run the AC generator to power the 60 amp AC powered battery charger. The available pulley ratios indicate the ~6HP lawnmower engine should be able to get the alternator up near its optimum 5000RPM or higher.


The lawnmower engine became available when the Toro walk-behind mower ate its drive mechanism one time too may and I replaced it with an electric-plus-manual start self-propelled Honda walk-behind. I have the sketch for a wheeled platform for the vertical shaft engine, the alternator and a 12 volt vehicle battery (so it can do serious jump starts if that is needed). The Toro's wheels and handle will make the wooden platform movable. There's a metal bracket for the alternator with the movable arm to adjust belt tension and I have some 3/4" plywood for the top of the platform.

That would be gen number 4 in my assorted backup power:
- 1600 watt inverter gen that's adequate for most outages.
- 3000 watt 120 volt gen for basic needs and running some repair/maintenance tools: circular saw, reciprocating saw, etc.
- 5000 watt 120/240 volt gen for basic needs, hand power tools and the 10" table saw, if needed. This was the bargain on Craig's List when the seller (who was asking maybe $150) could get it started but couldn't keep it running. I thought the throttle linkage looked bent so I offered $80 - and he took it. A little work with pliers and it started & ran fine - just needed a little choke (dirty carb jets?). I now have an ultrasonic cleaner big enough for that carb so that's a future project.
- adapted lawnmower engine and CS130 alternator - optimum for charging batteries when there is no sun.

I consider "crimp + solder" as the equivalent of "belt + suspenders" - and that's how I look at a lot of things.
Need to filter water? Have at least 4 options.
Need to cook? Have at least 4 options.
Need to Have at least 2 options for everything.

The new-to-me laptop I'm using has a glitch - the wifi card "goes away" with no warning - the network suddenly isn't there even though it was working five seconds ago. Reach back in my box of older wifi adapters and there's a USB 11AC network adapter. Plug it into the Win 10 laptop and within a minute the drivers have been found and the network connection is stable. This card has the gold mini screw-on connector and a separate 4 inch antenna so it sees more signal than a wifi card that's covered on one side by the metal chassis of the laptop - there was a time when the laptop makers put the wifi (and sometimes Bluetooth) card in the lid of the laptop (behind the screen) and gave it a good position of being "open" on all sides. I also have a multi-element Yagi antenna for 2.4GHz (wifi frequency - until 5GHz wifi came along) that could be connected to this wifi adapter and I could aim the Yagi antenna out a window and get to almost any router within a 100 yards or so. I don't plan on stealing the neighbors' wifi - but I might use it to report that my usual provider is out of service.