A genuine quote, similar to three others, for achieving a 12kW (peak) solar installation on the east facing roof below, with an appropriately sized battery. All companies simply planned to cover the roof with solar panels.
Spot the problem! (none of the professionals did including two who were on-site). The shadow is even worse earlier in the morning and in winter.
The light from the sun is a an oblique angle to the 45 degree roof when this shadow is gone. Common sense says that this is also an issue – the effective surface area of the panels is significantly decreased. None of the professionals commented on this during the consultations, although it is widely known that steep roofs are more sensitive to the direction of the sun.
Stop – what about the garage?!
Just below the picture on the front of the house is a 36m2 garage roof with little or no shadow, facing south. Only one company of the four contacted showed any interest in the small, but near perfect place for a solar array. Why… because using it would not give great headline figures and would cost much less.
Plan and do it yourself
The plan-it-yourself and do-it-youself 3.5kW solution on the garage roof cost less than €10,000 including battery. How much difference is there in real-world output compared to the 12kWp system? I don’t know, but my gut feeling is “not-much”. This DiY approach was not all plain sailing, but the results, measured in return on investment are undoubtedly a dramatic improvement on the professional proposals received.
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