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Photovoltaic Solar Electricity

Overview

The PV Solar system collects and converts solar energy to electricity. The system is tied to the grid, not independent or off the grid. Grid-tied means that generated electric power is fed back into the utility's power grid. As of 8 December 2014 the system comprises:
  • An array of thirteen ( 13 ) SunPower SPR E19/240 and eight ( 8 ) LG ELectronics LG-300-N1C-B3 panels.

  • Twenty-one ( 21 ) Enphase Micro Inverters to convert solar to DC electric power. Micro Inverters are more efficient than traditional single inverters, because each inverter continues to convert electricity even when only part of the panel is exposed to sunlight, i.e. not shaded.

  • Enphase's Envoy Communications Gateway with Ethernet connection for both central and local monitoring of solar panel operation over the Internet.
The PV solar array, installed on May 20, 2011 on the sloped, southern roof of the house, generates approximately 5,500 Kwh (5.5 Mwh ) of AC electrical power annually. The generated power is routed via a 200-Amp breaker panel to the City of Palo Alto's electric meter on the house. Due to underpowered design of the initial installation, five ( 5 ) SP-240-E panels and inverters upgraded the array to projected future electricity needs in March, 2012. Another eight ( 8 ) LG-300 panels installed on December 8, 2014, raised system power to nearly 6 Kw.

Electrical use on the premises averaged 2,800 Kwh ( 2.8 Mwh ) per year through 2010/11. Fossil fuel conversions ( esp. gas => electric heating ), and other electrical uses, are increasing our annual consumption to roughly 8,000 Kwh (8 Mwh ), on average 700 Kwh per month, with:

  • An on-demand, 20 Kw Tankless Water Heater for domestic hot water, replacing a 40-gallon gas water heater, that adds probably 2,000 KWh of usage per year.

  • An on-demand submersible cistern pump for potable water to the house, totaling 75 Kwh per year.

  • Submersible and sump pumps for distributing harvested rainwater to the yard and house.

  • The solar industry's rule of thumb is 1KW needed per year for every 5,000 miles driven. Our two 2017 EV ( Electric Vehicles ) are essentially sun-powered because charged entirely with 115V house current from solar generation. One overnight charge of 15 Kwh once or twice a week powers the vehicle. 'Fuel' consumption comes to less than $2.00 for every 100 miles driven, less than $10 per month. By comparison, at 50 mpg the Honda Insight hybrid's fuel cost nearly $40 a month for 10 gallons for about the same number of miles driven.

  • An on-demand, 12 Kw Argo AT-1226 Tankless Electric Boiler for home radiant heating (installed October, 2012), for probably 5,000 KWh of additional usage per year. The greater expense per BTU is more than offset by the increased efficiency of not maintaining boiler temperatures 24x7. The heating bill has dropped by $200 from the gas boiler's $700 per year.

Suppliers

Equipment & Service Vendor & URL
Solar Panels
  • SunPower Corporation
  • LG ELectronics
  • Solar & Breaker Panel Installer & Service
  • SunWork Renewable Energy Projects, Sobrato Center for Nonprofits, 477 Valley Way, Milpitas, CA
  • Real Goods Solar ( RGS ), San Jose, CA
  • Electrical Power Monitoring Software & Hardware Optimum Energy Products Ltd, Calgary, Canada
    The Energy Detective (TED 5000 ), Charleston, SC
    Roofer Bill Hamilton Roofing, Santa Clara, CA

    Resources & Links