ROI on solar water heating vs PV

realmoonunit

We are coming close to kicking off a reno and are weighing up the pros and cons of solar water heating vs PV (electric heating).



The cost of the PV is close on 8 times what we are looking at for the solar water. In real terms the payback (presuming all our electricity comes from the PV) is about 20 years! What I cant grasp is how long would the ROI be on the solar water heating? We would be looking at installing a new tank in either instance, and a new boiler (oil). The roof on the property was replaced in the last 6 years but needs a small bit of work c €3k in either instance.



But if we go with the water heater we would have plenty left to do an air to water system and MHRV. This route seems to make much more sense to me than spending on the PV. That added to the fact that in 5 years we will probably see improvements in the efficiency of the PV systems. Are we just throwing money away here? We are a family of 5 with soon to be 3 teenagers. If we did go the water heating we would get night rate meter installed.



So boards, what say you?

froshtyv

Standard house with oil would spend on average €200 a year for their hot water. (assuming heating up a 300 litre cylinder to 60 degrees once a day)
Say your solar costs you €4,000 supply and install.
€150 service cost every two years (manufactures recommendation) you are looking at 20+ years of payback also.

Yes you have plenty of hot water most days, but that is because you have already paid for it via your solar panels.

Ubbquittious

Do people really pay 150 every two years to get these things serviced or can you get away with far less? I might be overly cynical but I find the only way to get ROI in a reasonable timeframe with any of these things is to install them yourself and use a lot of second-hand parts. For the craic I put in 240w of solar panels a few years ago but it cost me less than €200 to put in. At that kind of price range you can see the thing pay for itself in 5 or 6 years but you have to be lucky that you can find a slightly used inverter for a reasonable price and that you have a spot where you can put the panels without too much effort.

corkgsxr

I donno how PV is that much dearer.

Put plain and easy pv system that will take from all the little things running around the house.

You go full battery and all sorts then yes its dear.

Ubbquittious

corkgsxr wrote: »

I donno how PV is that much dearer.

Put plain and easy pv system that will take from all the little things running around the house.

You go full battery and all sorts then yes its dear.

Full battery as in off the grid?