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 The
most popular form of backup power is the engine generator. While it is
possible to use renewable fuels such as Methane gas or Biodiesel, most
people opt for the less benign petroleum fuels such as propane or gasoline.
In a well designed solar system, backup power will be necessary less than
5% of the year. This translates into running the generator for a few hours
per week 2 to 3 weeks a year. Obviously actual run times will vary with
local site conditions and needs, but many of our more environmentally
conscious customers prefer to reduce their power usage rather than run
an often loud and pollution emitting generator.
INVERTER-GENERATORS
are a whole new type of fossil fueled electric generator.
They are lighter, quieter, more fuel efficient, and put out cleaner AC
power. Unlike regular generators that vary the voltage and frequency of
the electricity as the engine speed changes, the engine on Inverter Generators
can change speed considerably to meet power demand while voltage and frequency
remain stable. What does this mean? No dangerous power surges that can
ruin some appliances and best of all : These generators run AC battery
chargers much more efficiently, so a 2800 watt Yamaha inverter generator
(for example) can put as many amps into your batteries as a 5000 watt
or larger generator of a lesser brand. Inverter Generators are available
from 1000 watts to 3000 watts (3 kW)
 Portable
Generators
For larger loads and 220 vac output, we offer Yamaha's line
of Premium generators. They range in size from 4000 watts to 12,000 watts.
We also offer a 6600 watt diesel.
Wheel Kits, outdoor covers, and Propane conversion kits
are available for most Yamaha models.
 Stand
alone PROPANE GENERATORS
We have supplied Kohler generators for years on our larger
projects. Kohlers are available in up to 300 kW models. When we design
power systems that will auto start the generator, we won't use anything
less. Why? Other generators don't have the reliability of a simple 2
wire starting system. Other generators don't have the built in protection
features. Other generators might not be propane fired and so they may
have difficulty starting in cold weather, when you need them the most.
These generators all feature their own outdoor enclosure and mounting
base, so installation is easy, and permanent.
Autostart vs. Manual start
Some solar power systems can automatically start a generator
when the batteries get low, or to run a large load (like a deep well
pump). However, its much less expensive and simpler to start and stop
the generator yourself. If you do decide on autostart, we only recommend
the stand alone propane generators. Our Ranch & Commercial Systems
feature autostart generators.
Derating for Altitude
Since there is less air at higher altitudes, generators
make less power. Typically, we derate 2 to 3% per 1000 ft above sea
level.
Diesel: We do not recommend diesel for autostart in cold
climates, because the glow plugs and block heater necessary take too
much electrical power. For those in moderate climates that want to use
Biodiesel, this may be a good choice.
Our
Experiments in Biodiesel
What size generator do I need?
As a backup for solar power systems, a generator's continuous
watts (after derating for altitude) should be slightly larger than the
cont. rating of your inverter, or AC battery charger.
If a generator is too small: it will run for days
to recharge the batteries, or it will overload and shutoff.
If the generator is too large: it will use more
fuel, be louder, and cost more to operate.
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