We moved to our retirement lake home at the beginning of 2020. In fall 2021 we installed a large community backup power system for lake residences, resorts, restaurants and marinas on the lake. The lake we now live on is a quite large lake with over 100 miles of shoreline. The layout is such that county roads run on the south and western shores of the lake for 47 miles. The lake has a large island with about 30 residences on it. We own a large estate on the east shore with 640 acres and a mile of shoreline property. My wife is president of the Lake Assn.
This area is very rural and the condition of the power distribution is not very good here. It was run by an electric utility with purchased power from Xcel Energy. The HV interstate transmission lines are extremely vulnerable to lightning strikes, which destroys substation equipment and knocks out power to large areas. The economic impact of an extended power outage is quite severe for the businesses on the south and west shores of the lake.
So my wife spearheaded the effort for the Lake Assn to form our own power cooperative serving 1,337 members. We purchased two Caterpillar 3516B generators, 2.25MW apiece on prime, 2.5MW apiece on standby at a cost of $1.3 million each. We installed them at the substation that feeds the lake businesses and residences. These are distribution voltage generators operating at 7,200 volts. The switchgear bypasses the substation transformers that are usually damaged by lightning strikes. The Lake Assn covers three townships along the lakeshores, so we also got financial help from the townships. Previous to formation of the new power cooperative the uptime of the system was 94% with 22 days per year when the system was down. The generators were installed in Sept 2021 and to-date have accumulated 96 hours of running time with an uptime of 99.9% for the cooperative. I maintain and operate the diesel generating plant for the Lake Assn, and am president of the power cooperative.
Localized grid backup systems have been largely ignored in modern times. The system we purchased and installed powers about 270 miles of lines in three townships and is very cost effective, easily competing with cost of power purchased from Xcel. It is much more environmentally friendly, cost effective and efficient than the 1,337 services it powers all putting in their own individual backup systems. The only downtime involved when a transformer or HV fuse link is blown, is the time it takes to start the generators and bring them online. The cost of its installation, maintenance and operation is paid for thru Lake Assn fees to members, so it is a true community owned and operated cooperative that covers several hundred square miles.
In the engineering world this is called "economy of scale". "Economy of scale" is why standalone off-grid power costs many times more than utility power. The environmental impact per kWh also goes hand-in-hand with "economy of scale". When the backup system is online, we power 1,337 electrical services on only 0.15 gal/hr per service, which costs that homeowner or business less than 12 cents/kWh at today's diesel fuel prices. With vastly improved uptime over the old system that relied on central power generation from Xcel in another state.
When we purchased our lake home it was off off-grid. Typical with off-grid homes, especially those the size of ours (3,200 sq ft split level), it was very expensive to operate the power system costing us about 62 cents/kWh. After forming the cooperative we laid an under-water cable 1.5 miles across the lake from the big island to our place and 7 other residences on the east shore to provide utility power services. All the new services were buried so there is no unsightly powerlines on poles. It was one of the best moves we ever made as we can now enjoy fishing and boating, working in my shop and going about our life without worrying about batteries and cleaning snow off solar panels.
The seven residences on this side of the lake, including ours, are all 1.5-3.0 million dollar lake homes originally built by doctors, and they were built off-grid because the utility power didn't exist here. We bought our property from an estate and weren't really too worried about the off-grid aspect since we were used to that. But the cost of operating it, and labor time required, was astronomical. After we got the utility power, over the winter we sold our twin Outback Radian inverters, forklift batteries, solar panels, controllers, etc. to somebody who can make better use of them. The only thing we kept is our 150KW Caterpillar diesel generator which now supplies power to the cooperative when the standby system is running at the substation. It reduces the overall load on the Cat 3516B's. There are 46 other cooperative members that also have standby generators, which we incorporated into the standby system much like we did ours.
it is testament to the reliability, efficiency and cost effectiveness of distributed local power generation managed by communities instead of large utilities. The six other residences that were off-grid still have their solar panels, inverters, batteries, etc.. But it is very difficult for us to integrate that into the cooperative system because their output is not reliable or constant, and it is insignificant in the big picture. As president of the cooperative I have worked with those homeowners on a solution to allow them to use their systems to receive a break on utility rates. But the fact is, they can't generate power at the same cost we can, and as a small cooperative we can't subsidize them like the government can with taxpayer money. So at the present they use their systems to disconnect from the utility at certain times. But they are on the utility more than off it, even though each one of those homes has $70,000 worth of off-grid power equipment. Previous to the utility power they just ran generators like we did.
