In Japan, new energy sub committee under Agency for Natural Resources and Energy, Ministry of Economy Trade and Industry (METI), formulated the goal to be established the total of photovoltaic systems - 48,200,000 kWp in 2010. Consequently, photovoltaic systems intend to be a main generation of renewable energy, and a large number of PV systems installed in Japan has been the top of the world. Technologies of the PV system, in contract, are considered to be still scant and are deemed necessary to improve more in tandem with penetration of PV. Especially technologies for reliability of operation seem to be the most important because somewhat troubles or effect have been informed from existing PV systems such as a system rate issue, maintenances, and system failures. Even though they are known as the maintenance free generation, PV systems have to be monitored and evaluated their output energy since certain troubles have been reported that PV systems could not generate energy as much as they are expected; for instance, effect shading around buildings and trees, problem the failure of system rating, the repression of output energy by over voltage control, and the failure of construction, and so on. Moreover, the output energy is more important than PV system rate if environmental issue is focused. As of now, output energy from PV systems is not clear due to that it is difficult to characterize actual performance of PV systems. As a result, an evaluation method for PV systems seems to be necessary because evaluations is useful and helpful for the management of PV systems operation as well as output energy.

Therefere, we have taken two approch to development such as evaluation methods and simulations. In addition, to develop the simulation, estimation of shading effect is very important study. our research include the shading by several approach. Simulation are grid connected system mainly, and it should be noted that grid connected PV system with battery. Moreover, we have studied the characteristics of areally distributed PV systems such as smoothing effect.

The SV method has been developed as an evaluation method, which is using monitored data. During converting input energy into output energy, the PV system has numerous kinds of losses, which seem not to be measured. The SV method, however, can estimate system losses from irradiation energy (optical energy) to system electricity output power (AC power). Evaluating needs typical four monitored data such as in-plane irradiation data, cell junction temperature - which can be estimable from ambient temperature, array output power, and system output power, so that the system losses are allocated the part of the total system loss. For the latest version of the SV method, classifiable characteristics of PV systems are eight factors: shading losses, optical losses, losses by load mismatching, temperature effect on module efficiency, power conditioner standby losses, power conditioner efficiency, DC circuit losses, and the other losses which reduce the fundamental system performance, for instance; soil on modules, depleted modules, and the erroneous system rate.