How do you guys keep track of ROI on your panels / battery?

QrizB

arty688 said:

If you are looking at PV in purely in money terms can be complicated as you need to consider how much you could of earned investing that money or how much interest you are paying if you loaned the money.

You don't know today what interest rates will be for the next 25 years, but you also don't know what electricity prices will be either.

arty688 said:

Also ROI usually means return on investment not return of investment.
so you spend £15k on solar and save £1.5k the ROI is 10%
Once installed the value of the equpment is i would say written off as probably not worth much second had as removing it would cost a fair amount.

Which is why Internal Rate of Return is such a useful concept.

https://en.wikipedia.org/wiki/Internal_rate_of_return

There's even an Excel function, IRR, that calculates it for you.

arty688 said:

The other unknown is how much it has added to the value of the house.

Zero, unless you find a buyer who values it above zero.

arty688 said:

What I do do is make sure I'm on the right tariff to save me as much money as I can which I think is more important. Just swopped to EON next drive as much cheaper for me than Octopus.

9p off-peak, 30p peak on Octopus Go still does it for me.

Last year I used something like 1350kWh off-peak and 150kWh peak. 90% off-peak. At current Go rates that's a weighted average price of 11.1p/kWh.

arty688

It was the best Tariff for me as my car/charger wasn't compatable with Intelligent .

Also let me know if you need a referral link

SuzeQStan

arty688 said:

It was the best Tariff for me as my car/charger wasn't compatable with Intelligent .

Also let me know if you need a referral link

Does the referral come with a bonus for the switcher too @arty688?

Netexporter

SuzeQStan said:

arty688 said:

It was the best Tariff for me as my car/charger wasn't compatable with Intelligent .

Also let me know if you need a referral link

Does the referral come with a bonus for the switcher too @arty688?

Both parties get £50.

SuzeQStan

ecraig said:

9.5p off peak charging + 16p export on eon is currently looking quite attractive…

That sounds pretty good 

Nick_Dr1

powerful_Rogue said:

I've been tweaking it as things have changed. Now I don't bother using the export rate to calculate, as it changes on flux, so just put the actual £ i've saved instead each month.

If you use Octo-aid it will allow you to download your export for every 30 mins, including the rate that applies at each 30 min period. So you can then see how much you have exported at what rate. Some people might be interested in that!

arty688

QrizB said:

arty688 said:

If you are looking at PV in purely in money terms can be complicated as you need to consider how much you could of earned investing that money or how much interest you are paying if you loaned the money.

You don't know today what interest rates will be for the next 25 years, but you also don't know what electricity prices will be either.

fdfdarty688 said:

Also ROI usually means return on investment not return of investment.
so you spend £15k on solar and save £1.5k the ROI is 10%
Once installed the value of the equpment is i would say written off as probably not worth much second had as removing it would cost a fair amount.

Which is why Internal Rate of Return is such a useful concept.

https://en.wikipedia.org/wiki/Internal_rate_of_return

There's even an Excel function, IRR, that calculates it for you.

arty688 said:

The other unknown is how much it has added to the value of the house.

Zero, unless you find a buyer who values it above zero.

arty688 said:

What I do do is make sure I'm on the right tariff to save me as much money as I can which I think is more important. Just swopped to EON next drive as much cheaper for me than Octopus.

9p off-peak, 30p peak on Octopus Go still does it for me.

Last year I used something like 1350kWh off-peak and 150kWh peak. 90% off-peak. At current Go rates that's a weighted average price of 11.1p/kWh.

There is a fair amount of historical data on investment returns so you can take a guestimate

IRR looks complicated I like to keep it simple

I would guess solar panels on a house is more attractive now than it was to buyer.

Its the off peak being 00.00 to 0700 that swings it for me as in the heating season I can heat the house up in the morning off peak.

SuzeQStan

That longer off peak term is more attractive 

silverwhistle

EricMears said:

Fitting solar panels was a 'no-brainer' in 2011. 

Similarly in 2013 when I returned to the UK and my house. If the tenant had been decent, the sort who paid their bills and answered the door they could have benefited for a couple of years. As it was I did my research abroad and the panels went in a month after I moved back in, using my rainy day Cash ISA, and losing naff all in interest.

My calculations on returns were pretty post-it note size, and the usual variables: how to value water heating from the iBoost, do I factor in less wear and tear on the boiler and so forth? Lack of worry about bills must be considered too, but I couldn't quote any overall figures for those so minded.

Although a small ex-council terrace I have bigger frontage and roof area on the South than the North so luckily space for 4kWp. With the savings I've made further investment is in order so maybe A2A HP. I've got a big enough battery in my MG4 so I'm holding fire on a domestic one for now, but think next time I'll get the spreadsheets out.