First, we always like to preface jobs with this thought…
The best measure to minimize utility costs begins with an energy audit on existing buildings, or an energy efficient design and select construction materials for new buildings. Only after this, can solar plays its proper role. As we calc a system design, we may find solar will have little impact, but at least you will have the factual information to help with decision making.
When a building’s history of kWh usage and cost data are available from the utility company, we can provide supporting calculations as to how a PV solar system will perform, especially as it relates to the economics. With new construction we need energy modeling data to properly size the solar system and substantiate the performance. This certified modeling data must also be submitted to utility companies and/or the California Solar Initiative to obtain any applicable incentives.
Energy studies take into account occupancy criteria, lifestyle, insulation, windows, mechanicals, electrical loads, temperature zones, body heat and etc, to produce an estimated consumption model as an important benchmark needed to reasonably quote a PV solar system.
From this data we design the system to the sweet spot for the best return on investment. This factors hardware costs, labor, maintenance, financial incentives, DC and AC power losses, energy rate tiers, and utility cost increases over time, among many other key drivers.
So for these reasons and more, we hope you understand it is not possible to accurately quote a PV solar system that will authoritatively state the reduction in utility kWh usage and cost without this data. A solar quote would simply be invalid… and this is where good homework begins!