PV invertors

[graeme210375]

I am of the understanding that the invertors used in a PV instal have a life expectancy of around 15 years.
Is the replacement cost factored into the payback figures?

 

[whinmoor]

Generally speaking, no.

Some inverters will last for decades. Some will fail sooner. It depends on a whole range of factors like its build quality, location (cooler = better), how well matched it is to the panels, etc. All inverter manufacturers I've come across offer at least a 5 year warranty and some will go up to 20 years. Extended warranties are usually available if the customer wishes to go down that avenue but we don't encourage them to do so.

 

[FB.]

I am of the understanding that the invertors used in a PV instal have a life expectancy of around 15 years.
Is the replacement cost factored into the payback figures?

Unlikely.

I generally allow 1/20th of the purchase cost each year as a set-aside to cover repairs or replacement as the system ages. This 1/20th allowance also reflects that, unlike cash in the bank, the money spent on solar can't be "cashed-out" and spent along with all the interest (Feed-in-Tariff) received.


So if I'm paying £6000 for a 4kWp system
- and -
It generates 3600kWh per year
-
then I'd expect to receive about £600 per year in FiT and export payments.
- and -
use about one-third of the power in-house (£150 bill saving)
-
For a total "profit" of £750 in year one.

But I need to offset 1/20th of the £6000 against longer-term repairs or replacement, and to reflect that once spent, I can't cash-out as I could with an ISA.
That's £300 per year "loss" against £750 "profit" for a net gain of £450 per year, or about 7.5% annual return on investment.

 

[graeme210375]

Offsetting some of the income is a wise idea. A bit out of touch with PV, sold PV systems for Everest (via Eaga) about 2 years ago but FIT's were far more attractive back then. However, the market still seems quite buoyant despite the FIT reduction. Got part P assessment in 2 weeks and may consider taking additional training to move into PV installations. Had concerns about the inverter life spans as I tended to be a stumbling point in the sales process (i was very honest). But it appears that you pays your money and takes your choice. Mind you, it will be a great additional income stream in the next 10 year's or so, replacing invertors.