Many homeowners are interested in photovoltaic (PV) solar systems to supply their own domestic electricity. But how many PV panels are needed to achieve what? And how much should you spend on a system for a sensible return-on-investment of 7 years?

 

Panels (250W)	kW capacity	Est. monthly return €	Price of system for 7-year ROI *
1	0.25 kW	€6.50	€575
2	0.5 kw	€13.25	1.150,00 €
4	1kw	€26.50	2.300,00 €	Beware any exaggerations
8	2kw	54,00 €	4.600,00 €	beyond these figures
12	3kw	82,00 €	6.830,00 €	- false claims abound!
18	4,5kw	120,00 €	€10340
28	7kw	188,00 €	€16310

* Based on current EDP rate of 19 cents per kW (incl. IVA)