Redland Rambles

At the Small Farms Conference, Nick and Margie Pikarsky of Bee Heaven Farm were part of a panel on solar power.

Nick Pikarsky

They gave a presentation on the two solar systems they have installed at their farm. One is a passive hot water collector, and the other system powers a water pump and freezer.

Water pump and freezer system

This system is used to pump water from the well for the bar, with extra power for the freezer. The pump provides water for everyday farm water uses. The system also does minor irrigation in a small area, consisting of a small mist house and a garden size drip system.

Solar panels mounted on roof of pump house

Two solar panels are mounted on top of the freezer shed, and were set at a compromise angle between summer and winter positions. Since the farm is so close to the equator in South Florida, the angle of the sun doesn’t change much through the seasons. They learned quickly that you can’t have anything obscuring the panels. A crawling vine once covered part of one panel and reduced the power output considerably. When nearby branches and a flowering bush grow too tall, they get cut back. After hurricanes Katrina and Wilma, the farm was without power two weeks and one week accordingly. The house didn’t have water, but the barn did, and the system was hooked up to supply for the house as well.

24V Dankoff Solar Force irrigation pump

Nick researched the literature, spoke with suppliers and decided on a 24 volt DC system as a compromise between efficiency and economy. 12V systems are cheaper but more inefficient, and 48V systems were a bit too expensive. Choose the type of pump based on your needs — depth of water table, amount of water needed, and duty cycle — then size the solar system accordingly, Margie advised. The irrigation pump is a 24V Dankoff Solar Force (now sold under the Conergy brand). The pump system runs off 2 deep-cycle batteries charged by a small controller unit. It also powers a Sundanzer 8 cu. ft. 24V freezer chest, and a couple of emergency lights in the barn and pump house.

Inverter and breaker panel mounted on wall. Batteries, pump and freezer on the floor of the pump house.

Passive water heater

Bee Heaven participated in Florida Keys GLEE a few years ago and learned about TCT Solar, which makes passive solar hot water collectors. This particular model is 50 gallons, and was mounted to serve as the roof of an outdoor shower stall. It provides plenty of scalding hot water for the shower, a washing machine, and the big sink in the barn. The passive system heats water only when there is sun, but the water stays hot! It requires no electricity and works really well.

Passive collector mounted on top of outdoors shower.

Barn system

There is a third system at Bee Heaven Farm that has not yet been fully implemented. It will someday serve all the power needs in the barn. The barn
has a Solar 5K 48V inverter which is designed to power the walk-in cooler, tools, lighting and standard 120V AC appliances. Nick and Margie calculate they need a total of 20 PV panels to power the barn, along with a complement of 40 batteries. It’s too expensive to do that all at once, so they’re hoping to implement in stages, and are excited about new government incentives to help with the purchases. There’s an A-B switch in the barn to go on or off the grid. Margie said their goal is to be completely free of the grid.

Barn breaker panels, A-B switch and inverter.

FPL has a net metering policy, but there’s a catch, Margie cautioned. They require you to be down when they are down, and you have to buy power from FPL at retail, yet they buy power from you at wholesale, and that’s a significant difference. FPL will give you credit if you generate more power
than you use, but at the end of the year, you lose any credit you’ve accumulated. Other speakers on the panel cautioned users to try to negotiate a contract with their utility that’s equitable.

Costs

These are the prices when the systems were built 5-7 years ago. Some things are now cheaper, and some things are more expensive.

Solar collector for hot water $1400 (copper piping and stand not included)

Pump and freezer system:
Batteries 400 x 2
Sharp modules (solar panels) 550 x 2
Rack for modules 200
Charge controller 140
Dankoff pump 2500
Pressure tank 200
Sundanzer freezer 1200
Total: 6200 + labor & shed

Download system diagrams for the solar water heater and for the solar pump.

Thanks to Margie for collaborating in the writing of this article, and Nick for the systems diagrams.