Villa Systems Management
Seeing as Steve is and always will be a farmer and engineer at heart, we've got to display the systems that help keep our villa operating and a great place to stay for our guests. So this is where we geek-out and present data for those interested in the technology behind our particular vacation rental villa on St. John.
Water is life. It is the fundamental need of everyone and everything (besides air and rum) on St. John. While Cruz Bay has a city water system, most buildings out of 'town' are built around concrete (or sometimes plastic) cisterns and roof gutter systems that capture rain water. From there, some choose to use that for sinks and showers, but buy bottled water. Others, like us, have multi-level filtration and sterilization systems in place to provide clean drinking water at every faucet.
At Great Expectations, we have 3 potable water cisterns - 1 underneath the Guest House, and 2 under Building #3 of the main villa. The Guest House villa holds just under 11,000 gallons of water, while Villa East & West Cisterns hold 13,900 gallons each. This gives us a combined storage capacity of 27,800 gallons + 11,000 gallons = ~39,000 gallons.
We've installed 3 wireless cistern monitors from PTLevel in Canada that let us see how much water we have, as well as how much is being used and how much is being added from rain.
Great Expectations has 2 types of water filtering devices on both the villa and guest house water systems.
Directly off of the cistern water lines is a series of 3 canister filters that scale from a 25 microns down to 1 micron. They remove over 99% of all sediment, bacteria, other particulates, and tastes.
Immediately following those filters is a high-capacity UV light system that sterilizes the water, inactivating any harmful bacteria and viruses that remain.
Why take from the fuel-burning power station a whole island away (St. Thomas) when you can capture sunlight, use it, and store it for night time or emergency use?
In February of 2018, after losing 80% of the villa’s photovoltaic array during Hurricane Irma, we hired ProSolar to rebuild our rooftop solar system including 26 of the remaining 210 Watt (W) solar panels and 30 new 300W panels. This array gave us about 14,500kW of power generation at 100% efficiency. In January of 2019, we added another 18 x 300W panels expanding our system to 19,860kW.
26 x 210W = 5,460W
After monitoring continuously for 9 months, we average the equivalent of 5 hours of 100% production - which actually comes in over a 12 hour period from sunset to sundown of 0% to a peak of about 95% back down to 0%.
(26 panels @ 210W) + (48 panels @ 300W) x 5hours = ~99.3 kWh production per day
With island grid power costing almost $0.40/kWh, you can see the solar array produces about $40/day or $1200/month of electricity.
Power Storage, ReUse and Emergency Backup
Tied into our solar array is one of our tech pride and joys:
5 x Tesla Powerwall2's
Each Powerwall has 13.5kWh of usable energy storage with the ability to charge and discharge at a continuous 5kWh with discharge peaks of up to 7kWh at over 22A. With 5 of them together,
5 x 13.5kWh = 67.5kWh storage/backup @ over 100A of continuous power draw
The entire system is controlled by a web-connected gateway that constantly monitors incoming grid power (or lack thereof), incoming solar, Powerwall (dis)charging, as well as NetMetering of power back to the utility.
The beauty of the cloud-based control is that you can choose what how to use the energy:
Keep 100% of the Powerwalls charged up for backup power
Choose to “self power” the villa with 0-100% of all solar power generated (and stored in batteries for after the sun goes down).
Or create a time-based system for varying electricity rates, using solar and stored during peak times, and grid power during less expensive rate hours
Since the villa is setup for NetMetering with WAPA, and they credit back all power at the same rate (up to the amount consumed), we choose to leave the backup power set to 100% to allow the villa to run off solar during the day, send the excess power back for a credit, and have the ability to run grid-free day in and day out in the event of island power failure*.
*As long as there is moderate sun and we (or guests) smartly choose to not use Air Conditioning, the entire villa is self-powered.
The catastrophic infrastructure destruction from Hurricane Irma taught us all a lot of lessons. Communications were absolutely terrible for the first 2 weeks following the storm. Then Hurricane Maria hit and it didn't get any better. Probably 85% off all overhead wires were down or gone, and much of the wireless antennae on various peaks were damaged or destroyed.
We decided to double up and double down.
Since the hardwired and wireless internet options on island were not coming back anytime soon (it was 3 months before we got some sort of on-again off-again wireless), we shipped down a HughesNet satellite to use as the initial post-storm internet. Once poles were re-seated and restrung with fiber, copper, and coaxial cable, we got our VIYa 100/10Mbps hard-wired internet connection in late April 2018. We put the HughesNet in sleep mode and will save that for downtimes and future post-storm environments. With the solar panels and Powerwalls, we should be running off-grid with internet after a similar storm within hours, not days.
Wired + Wireless Infrastructure
We also decided having local WiFi access points that mesh wirelessly with each other was a mediocre solution at best. The villa and villa guests need to have consistent, high-speed internet to any and every device that is on site: SONOS music devices, Cistern monitors, weather station, Roku TV, and the grandkids’ iPads.
So we worked with Pirate I.T. to run conduit from the each of the main 3 villa buildings to a central network room built on the lower level of the Guest House. Each conduit run contains multiple ethernet and coaxial cable that allows us to send TV signal and currently up to 1000Mbps throughout the entire villa.
END RESULT: Primary Internet connectivity at 100Mbps with 35Mbps failover and >400Mbps wireless throughout our entire property. Surf on*!
*Although we’d recommend putting down the devices and enjoying the pool area!
In an island environment where you collect water from the sky, harvest energy from the sun, and live with the oh-so-real fact of future hurricanes, monitoring the weather is more than just a hobby.