Leave solar batteries out of the system until we have the house up and running?

[saveasteading]

We are fitting  solar and intended to include a battery system sized to suit estimated use.

But our electrician/plumber suggests we leave the batteries until the house is up and running, then size accordingly.

 

I was surprised, as it will take a year until we have reliable figures, and that's a year of not getting the benefit.

Plus we will not be getting in the habit of optimising.

 

The vat reclaim entered my reasoning until I twigged that it is zero anyway.

 

Is the electrician wary of estimating wrongly? Or wise?

Or perhaps undersizing or oversizing is more than a cash issue.

 

He also agreed we should get a 3 phase heat pump, which the solar people were resisting. 

On the principle that as we have 3 phase we should use it.

 

Thoughts please,

[JohnMo]

13 minutes ago, saveasteading said:

agreed we should get a 3 phase heat pump

If your putting a battery to cover your whole winter loads, it going to be huge and not cheap. I would size it now for an average winter day. But your tariff makes a big difference to the size, Cosy gives you 3 charge periods, a typical electric car tariff only one, so you would need a much bigger battery.

 

Just choose a battery that can be expanded, add more later if you want as slave units.

[SimonD]

It's funny you should raise this difference between heat pump installer and electrician. The electrician I use as part of all my heat pump installations called me a while ago pretty p***ed off. He'd completed a new house wiring installation plus solar & batteries on 3 phase. The heat pump people came along and just installed a single phase heat pump cascade, causing a bit of a headache. At least yours are talking about it. What is the size of your heat pump? And I'm guessing it's been confirmed the model is available on 3 phase? Probably a silly question.

 

I've had a similar experience with solar design for my place where the designer didn't seem to understand modular and phased approach. It's a bit infuriating. With the right system design there should be no problem scaling up if you need to, just as @JohnMo suggests. 

Edited 9 minutes ago by SimonD