Posted by dolmen on June 3, 2018, 10:08 am
On Saturday, May 26, 2018 at 4:24:17 PM UTC+1, Johnny B Good wrote
Thanks for the detailed reply, I'm in no way educated in the workings of th
ese, but rely on kind folks like you on the web sharing their experience an
d knowledge to inform me, then I makes my choice. I do have a larger petrol
open frame chinese type generator, it works but not so refined. At least I
'm not stuck when the power does go off, and it drives everything freezers,
oil burner, pumps and lights etc However the inverter one caught my eye bu
t never managed to get one and the much higher prices quoted for the red on
es leave a bad taste for something that is going to sit for months on end!
Changing the subject slightly, I was considering a Li-ion battery bank and
900W solar but having contacted 4 Companies not one was interested! and bec
ause its rather a lot of money I wasn't convinced I knew enough to DIY. I d
o have the generator changeover switch so a battery bank may well work with
the generator plus add solar at anytime. Run the generator to charge up th
e batteries and run quietly in the evenings.
Posted by Jim Wilkins on June 3, 2018, 7:37 pm
Changing the subject slightly, I was considering a Li-ion battery bank
and 900W solar but having contacted 4 Companies not one was
interested! and because its rather a lot of money I wasn't convinced I
knew enough to DIY. I do have the generator changeover switch so a
battery bank may well work with the generator plus add solar at
anytime. Run the generator to charge up the batteries and run quietly
in the evenings.
The problem I encountered with my solar battery system was the high
idle power of pure-sine inverters suited to 120VAC refrigerators. The
inverter I have runs continuously and consumes as much overall from
the battery as my small fridge. It needs to be sized for the starting
surge, which is 12A on mine.
I'm testing a Chinese Alpicool DC-powered fridge/freezer which can
operate directly on 12V or 24V. It has its own set of quirks to deal
with but so far it doubles the battery run time when it's the only
load, and may permit a smaller and more efficient modified sine
inverter for non-motor loads in the daytime.
Posted by ads on June 5, 2018, 2:04 am
On Sun, 3 Jun 2018 15:37:55 -0400, "Jim Wilkins"
Most commercial suppliers are not interested in relatively small
installations because the pricing they can give on big systems falls
apart below a couple of kw. There's similar setup time and labor for
a few solar panels as for 4 times that many as well as the wiring so
the costs for small solar don't work out.
I'm handy at finding good used and recycled gear, as well as finding
bargains in electronic equipoment. I put together a 12 volt, 540AH
(6480WH) battery bank with two 2000 watt pure sine wave (PSW)
inverters, a 500 watt PSW inverter, two 30 amp MPPT charge
controllers, 900 watts of solar panels and all the interconnect
wiring, fuses, circuit breakers and monitoring equipment for $100US.
The electronics were shipped but the batteries and solar panels were
sourced locally (no shipping, just gas for my truck). The solar
panels are not yet permanently mounted (still working out which of 3
possible mounting locations is the best location).
I do have 25 amps of precisely controlled battery charging equipment
that can be powered by a gasoline generator (NOT the $0 cheapie
charger from the auto parts store). An hour of that charging provides
1 to 4 hours of runtime from the battery bank, depending on the season
(more heat and light needed in winter and less sun available for solar
My design goal was "Wait until daylight" power so I would not be
setting up the gas gen in the dark or during a thunderstorm because
most of our outages are less than 16 hours. Depending on the season,
the system provides 10 to 20 hours of limited power. The design meets
my goal and I learned a great deal about solar power.
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Posted by dolmen on June 5, 2018, 10:01 am
On Tuesday, June 5, 2018 at 3:04:56 AM UTC+1, ads wrote:
Thanks ads, yes that was the conclusion I'd arrived at. Interesting that yo
u went for a 12V system I was thinking of at least 24V perhaps 48V and bein
g able to use lighter wire in the system, but like I say I don't really hav
e a clue. A similar setup to what you have built would probably meet my nee
Posted by Jim Wilkins on June 5, 2018, 1:52 pm
On Tuesday, June 5, 2018 at 3:04:56 AM UTC+1, ads wrote:
Thanks ads, yes that was the conclusion I'd arrived at. Interesting
that you went for a 12V system I was thinking of at least 24V perhaps
48V and being able to use lighter wire in the system, but like I say I
don't really have a clue. A similar setup to what you have built would
probably meet my needs too.
Mine can be configured as 12V or 24V, determined by the loads and the
nonfunctional 24V pure sine UPS I acquired for free. The Alpi can run
on either. I brought the solar panel wiring into the house as
individual 12V pairs and patch them in series or parallel at the
thunderstorm disconnect with nongendered 45A Anderson Powerpole
The circuit is conceptually very simple, basically wire it as the
label on the controller shows. However there are subtleties of fusing,
grounding, fault tolerance and battery care etc that I had to research
for myself and I doubt an electrician or electrical engineer would
know unless they had solar experience. I've discovered many times that
electricians don't know much if any theory and engineers rarely
understand the practice. As a tech I had to cover the overlap and know
which one to call and what to ask when I couldn't solve the problem.
For instance one of the input diodes on my 45W Harbor Freight
controller shorted, allowing battery voltage to flow back to the panel
where it could be a serious short circuit hazard. I had added cheap
analog volt and amp meters to the panel leads which showed the voltage
that shouldn't be there at night. A digital meter on the panel
downlead had failed, possibly from static voltage.
Another gotch is stray added resistance in the wiring, likely at loose
or corroded connections. One Ohm is hard to measure but is far too
much at 5A panel current. The Variac+welder power supply can force 10A
through the wiring which makes high resistances easy to find with a