The equation was proposed by Paul Basore in his white paper on LCOE, whereĬ mod( η) = C mod( η ref) ⋅ ,
In 2020, we added a new equation to account for how the price of the modules C mod depends on module efficiency η. Hence, the BOS costs can be represented by the equation, These can include some administration costs and other aspects to labour, the inverter, and cabling between modules and inverter. Inverter costs are indpendent of the system area.Ĭ F, BOS costs that are fixed and independent of the system size or power. This includes aspects of the inverter since it typically becomes more expensive to transform more DC power into AC power. In this calculator, they are simply represented by four variables:Ĭ M, BOS costs that scale with the number of modules in $/module, like the cost of bolting down and wiring up each module.Ĭ A, BOS costs that scale with area in $/m 2, like the land or roof area.Ĭ P, BOS costs that scale with system power in $/W p. The balance of systems cost C BOS is rather complicated to calculate as it is comprised of many factors: e.g., labour, frames, cabling, inverters, insurance, transportation, land. The number of modules N mod is equal to the system power P sys divided by the module power P mod, where the latter depends on the efficiency η mod and area A mod of each PV module: Where N mod is the number of installed modules, C mod is the cost of each module (assuming all modules are identical), and C BOS is the cost of the balance of systems.
The installed system cost C sys is given by: Thus, the installed PV cost is one step superior to comparing module prices in terms of $/W p, but more analysis is required to give a complete assessment of a module's value to a PV installation. These operational aspects are not encompassed by this calculator, which is specific to installed PV costs. Different types of modules also repond differently to changing operating conditions (temperature, spectra, intensity), they degrade at different rates, they have different failure modes, they require different degrees of maintenance, and so forth. It is pertinent to note here that the value of a PV module does not affect the installation cost alone.
Nevertheless, BOS costs should not be neglected because they typically contribute to more than half of the cost to install a PV system. For example, lighter panels might incur lower transportation and framing costs, annd flexible panels might be quicker to install.īOS costs vary significantly from one application to another, and from one country to another, so they cannot be evaluated with a generic value or fraction. There can also be structural differences that make one panel superior to another, but which are not entailed in the $/W p metric. It would clearly be cheaper to use the 20% modules, since that would require less land, less labour, and fewer frames, all of which make up a significant fraction of the cost of an installed system.
One could either install 100 m 2 of the 20% modules or 200 m 2 of the 10% modules. Yet this does not mean that a PV installation using the 10% modules would cost the same as one using the 20% modules.Ĭonsider the installation of a 20 kW p PV power plant. In general, comparing the price of PV modules on a $/W p basis makes higher efficient modules appear less cost-effective than they really are.įor example, if one could purchase a 10% module for $100, or 20% module for $200, and both modules had the same area of 1 m 2, then on a $/W p basis, the modules would cost the same: 1 $/W p (see equations below). These BOS costs depend on the efficiency and the structure of the PV modules. A PV installation also requires land, frames, labour, wiring, inverters, and other electronics, all of which are lumped under the term, Balance of Systems (BOS). The problem with comparing modules in $/W p, however, is that PV electricity is not generated by modules alone. The benefit of this metric is that it is simple, and that it helps to compare modules of different sizes and efficiencies. It is common to compare PV modules in terms of dollars per peak watt ($/W p) that is, by the price paid for a module divided by the power it produces under standard measurement conditions.