Wind, solar, storage and back-up system designer - Page 5

 On Sun, 7 Jul 2019 16:34:14 -0700 (PDT), Scottish Scientist


I've noted the line on the link and will check it out.

I'm also aware that the tree cover here precludes a whole-house solar
system.  I'm aware that I probably wouldn't live long enough to see
payback on a whole-house system, notwhen including the cost of
removing those trees and the increased air conditioning costs if that
shading was lost.  

This also isn't an area where alternate energy is a selling factor for
houses, which becomes obvious when you look at the number of used
solar panels that are available - for me, that's the local
craigslist.org where panels that are one or two years old are
available in quantity, as are AGM batteries of similar ages.

My primary use of solar power is stand-alone small systems (lighting
in a shed out back that would require boring under a driveway to run
AC power) and my short term solar-charged backup system - my "solar
generator" - see a previous post for the details.

Small systems have their uses - and I do have gasoline generators as a
fallback, from an efficient 1600 watt inverter generator (6-8
hours/gallon at 800 watts)  to a large, loud, heavy, thirsty 5000 watt
gen that can run the table saw or the wire welder and angle grinder if
I need to do serious work when commercial AC is out.

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Is that the Harbor Freight inverter generator? I have the older 2200W  
model which I load-tested to its limit with electric heaters and a 20A  
Variac, just before the warranty expired. The output held a solid 120V  
right up to the 19A overload trip and it recovered when the load was  
reduced.

I found by experience that I need at least a 3KW generator (bigger  
would be better, but see below) to handle the starting surges of my  
washing machine and air compressor motors, and to power woodworking  
tools to quickly repair roof damage from the storm that caused the  
power outage. The 3KW generator only starts them if I push the  
spring-tensioned washing machine motor inward to loosen the belt or  
depressurize the air compressor head, so I made a manual opening lever  
for the pressure relief valve.

I hadn't planned on needing compressed air during a power outage but  
it was necessary to blow out the clogged carburetors and inflate the  
flat tires on neighbors' generators. I intentionally don't own a  
generator large enough to supply anyone else's needs but I'll help  
them get their larger one running in exchange for tapping into it.

So far I haven't needed to weld or run machine tools during an outage.  
My main and backup snowblowers both have stronger home made metal  
replacements for flimsy failed parts so it could happen. Both were  
$
00 fixer-uppers; carb rebuilds and a couple of new belts, shear pins  
and bushings etc saved me over $
000. During and after a snowstorm the  
town's road crews do a fine job of keeping the streets clear but we  
have to hack through 3-4' high packed snowbanks to get out of the  
driveway.

The smallest generator I know of is the Kohler PowerPlay 500, a loud,  
poorly voltage-regulated 500W 2-stroke.
https://www.ebth.com/items/3587795-kohler-gas-powered-powerplay-500-watt-generator  
It was all I had the first time an ice storm dropped tree branches  
through my roof. I ran it on my roof's level chimney-cleaning platform  
and used it to keep a Makita battery drill and 4" panel saw charged to  
cut out and replace punctured roof plywood. I cut and notched the ends  
of the replacement rafter with a saber saw.

When I removed all the loads from the Kohler its voltage rose above  
140VAC, frying the surge suppressors in an outlet strip in a cloud of  
purple smoke. Afterwards I tamed its output with a Variac. I also  
installed Home Depot roof safety anchors that attach under the ridge  
vent in case I have to work up there again when it's covered with ice.  
When you desperately need to hire someone to work on your roof they're  
all booked solid for other peoples' roofs.

 On Mon, 8 Jul 2019 09:40:03 -0400, "Jim Wilkins"



The inverter gen is a Wen that ended up costing me $
50 because FedEx
damaged it in shipping.  When it didn't start after 10 pulls with
fresh gas, I checked the shipping cardboard box for damage (nothing
obvious on the gen housing) and found what looked like a fork lift
puncture.  Opening the clamshell (only needs 3 hands ;-) I found the
bracket on top of the carb that holds the stepper motor that controls
the throttle was broken.  Filed a claim with FedEx, including pictures
and sat back for a long wait.  Meanwhile, I checked online for a
replacement carb and none of the distributors had it listed as "In
stock" so I sent emails.  One distributor had *one* carb on the shelf
but that's not enough to list online.  Called and got the carb ($
0
and free shipping).  Got a check from FedEx the next week.  The
shipper hadn't listed a value on the shipping docs so I got the basic
$
00 and a refund of the shippoing cost.  That paid for the carb and
took $
0 off the price of the gen.  Spent more than an hour finishing
the disassembly of the gen so I could replace the carb - and lost less
than a teaspoon of gasoline in the process ;-)  After getting it back
together (also needs 3 hands as the gas tank is held in groves molded
in the clamshell halves and you have to put that back together by
feel), it started on the second or third pull.  I checked it with a
500 watt halogen light and a 1000 watt electric heater and it works
fine.

The 5000 watt gen was a Craig's List deal.  The seller was asking
something over $
00 but he couldn't keep it running after getting it
started.  I thought the throttle linkage looked a little bent so I
offered hin $
0.  A little time with pliers to get the right angles in
the throttle connections, adding an oil filter, changing the oil and
it works.  I don't have a 220 inlet for that gen, just a 220 plug for
the gen and a split 120 quad outlet at the end of some 12 gauge cable.
I can honestly tell a neighbor that I don't have the cable to provide
them 220 for their heat pump, dryer or central A/C but they can run an
extension cord over for the fridge and some lights if they provide
some gas.

There's also a 3000 watt Champion gen that I got from Northern Tool
for a reasonable price at the end of that model's production run.  The
waveform isn't the best - more like a lowercase "u" and a lowercase
"n" with curved top and bottom and mostly straight sides - and some of
the UPS units won't power up on that gen - but the battery chargers
for the solar system don't care about the incoming waveform so I can
charge the battery bank if there is no sun.

You've probably guessed that I have buckets of beans and rice in the
basement ;-)

 On Sun, 7 Jul 2019 16:34:14 -0700 (PDT), Scottish Scientist


Some questions for you:

How far do you plan on discharging those batteries?

How many days of little or no sun do your calculations include?

I know that we can easily have a week or more of cloudy, rainy days in
winter and my best solar panel only produces about 5% of its rated
output on a rainy day.

The past two weeks, we've had summer thunderstorms almost daily, with
there being less than 50% of "normal" sun most of those days.

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Under those conditions I see more charging current from the PWM  
controller than the MPPT, because the MPPT consumes more internally.

I just replaced the (11 year old) battery in my car after a single  
accidental full discharge significantly reduced its cranking capacity  
and increased its self-discharge. It would drop below 12.2V a week  
after fully charging it, and the car's key-off current drain hasn't  
changed.