The house is 2,600 square feet (242 m2), passive solar, and super-insulated, with a gorgeous view of the surrounding valley. They were told that the house had an “off-grid” electrical system. Being from the city, they had no idea what that meant. Nor could anyone vouch for its reliability.
Eric Westerhoff of Innovative Energy, the PV dealer from nearby Breckenridge, was contacted by the realtor to inspect the electrical system. What Eric found was that nightmare known as “the handyman’s special!”
A Bit of History
The power system for the house was initially installed back in the mid-1980s, but evolved through the years. When we arrived on the scene, it consisted of twenty Kyocera 50 watt PV panels mounted on the roof. The PVs were series-paralleled, configured in five arrays with four panels in each array. Three of the arrays were regulated by one Trace C-30 charge controller, and the other two arrays passed through a second C-30. Maximum output of the 24 volt PV system was 35 amps.
The batteries and some of the controls were replaced in 1988. The new 24 volt battery bank consisted of twelve Trojan L-16s, series-paralleled for 1,400 amp-hours of capacity. Backup power was originally supplied by an 8.5 KW Onan LP (propane) generator through two Todd 75 amp battery chargers. Three 2,500 watt Heart Interface inverters supplied AC power to the house.
When the property changed hands in 1992, the new owners ran a small jewelry shop out of the house. It was during this time that the system fell into disarray. In order to meet production, the owners had to max out the system on numerous occasions, which eventually damaged the battery bank. The system was well used, but obviously with little preventive maintenance. Entropy set in, and system output declined. The owners depended on the Onan genset more and more.
Upon inspection, Eric found that the L-16s were more or less dead after only five years of service. During the day when the sun was shining, battery voltage climbed to 28 volts. When the sun set, however, the system voltage quickly fell to 19 volts. As a result, the inverters shut down due to low battery voltage at night, and power had to be supplied to the house by the LP generator. Eric characterized the installation as “basically a direct drive system. You’ve got solar lights during the day, but LP lights when you most need them.” Just prior to our arrival, the worn out Onan was replaced with a Generac 5,500 watt gasoline generator.
Eric remembers first approaching the battery/ inverter/controller room and being overpowered by the smell of battery fumes. There was obviously something wrong. Among other things, Eric discovered that the Trace C-30s were operating continuously in the equalize mode. This resulted in the batteries merrily boiling away on bright sunny days.
Needless to say, the battery room was a toxic waste site. Battery acid had boiled over onto the concrete floor, etching canyons into the cement. Battery acid wicked up one wall of the room, dissolving the drywall in the process. The battery box hardware had begun to vaporize from the acid fumes. The previous owner had covered the spills with various layers of indoor-outdoor carpeting. As the carpeting decayed in the acid, bits of rubber and tuft were tracked away by visitors. Fortunately, most of the acid had been neutralized by the dissolving concrete.
Eric’s inspection report to the realtor indicated that not only did the batteries need replacing, but the battery room also needed a complete overhaul. Once they closed on the house, Lou Ann and Kelvin bought new batteries from Eric. They also requested a general tuneup of the RE system.