SolaSave CIS thin-film case study

The project

The SolaSave team provide our customers with solar panel systems for a range of diverse property types. Our first step – along with chatting to our customers - is to go and see the property in question to provide a free survey, followed by a written fixed price quotation with no obligation.

On this occasion we received a request to assess the feasibility of installing solar panels on the roof of a south facing single storey property. The house was located next to a two storey neighbouring house. It had a tall chimney at the bottom of the roof and there was a telegraph pole in the grounds of the property extending more than two storeys high.

Together these factors resulted in shading on various sections of the roof throughout the day.

Shading analysis

The UK Department of Energy and Climate Change endorse the use of a Microgeneration Certification Scheme procedure. This generates a sun path diagram to estimate the predicted annual yield for a given property. This analysis is an absolute requirement for people to benefit from the currently available government feed-in tariff.

SolaSave created a sun path diagram with the shading objects and the result is shown below:


The Solution

Given these conditions, it could be argued that the property was not suitable for solar panels, and that the project should not go ahead. But what the MCS procedure for shading analysis does not account for is solar newer technology to mitigate the effects of shading. We were confident that we could design a system that exceeded the kWh levels predicted from predicted annual yield calculations.

We could have chosen the micro-inverter or power optimiser route but instead we opted for thin-film technology which we consider to be a far more effective solution. We used Solar Frontier thin-film panels. These have the advantage of meeting RoHS criteria as the modules are free of lead and cadmium.

We created 5 zones (strings) on the roof and used a dual tracking inverter which provides independent optimisation on each of its two inputs. The inverter is made by leading inverter manufacturer SMA and features opti-trac technology which we also enabled and configured. 


The system was commissioned 26th March 2014. By the end of February 2015, the customer gave a meter reading of 2,787kWh against a forecast of 1,823kWh, around 52% above prediction. The system was calculated at SF0.54 according to the MCS shading method but has performed as a SF0.89, just 11% yield loss despite the severe shading conditions.


We were asked to provide a solar survey for a property with a roof in the shade. Normally, this type of property would have been deemed unsuitable for solar panels. However, using CIS thin-film solar panels, we provided our customer with a system that out-performed the expected power output and generated a sufficient amount to power for a property of its size. Needless to say the customer is delighted with the performance.

This is one of many of these thin-film systems that we have installed and we are pleased to report that they are all achieving similar results. Recent years have seen advances in CIS thin-film technology and a decrease in the overall cost of energy. In an era when people are interested in switching from fossil fuels to renewable energy, we think that this form of solar panel technology will see an increase in its use – ideal for our cloudy British climate.