C1 BER House - How to approach upgrades?

[CharlieMac]

...and a battery!

@conor_mc What do you use your battery for? You can't really run just any appliance off it can you, like a cooker, fridge or electric shower?

I don't have solar, yet, but considering getting a battery, charge it up overnight on EV rate then run an oil filled electric space heater off it during peak times. Probably a long payoff given cost of battery mind you.

 

[conor_mc]

What do you use your battery for? You can't really run just any appliance off it can you, like a cooker, fridge or electric shower?

It’s a household battery connected to the PV system’s hybrid inverter. Gives your PV system considerably more options to make savings depending on the tariff regime in place. For example, at the moment I fill the battery overnight at 14c and allow my solar to export earning me 20c a kWh when I’m not consuming it, this avoiding daytime 28c units. Just in process of swapping out my 5kWh battery for a 15kWh battery which will allow me to switch to an EV tariff, filling the battery overnight at 5c and exporting at 25c but avoiding (for the most part) the very expensive 38c daytime rate that comes with that tariff. We also have 2 EV’s but fairly short commutes so don’t do a huge amount of charging the cars overnight.

If the currently generous feed-in tariff that I can sell electricity for is reduced, eliminating that 25c-5c margin, I’ll switch to filling the battery with daytime solar instead of exporting it, making sure I self-consume more of that generation. You really can’t lose by attaching a battery to a solar PV system unless you pay too much for it.

Some of the prices of installer-provided batteries are very expensive but can be gotten elsewhere cheaper. I was quoted €2250 for a second 5kWh battery but ordered a 15kWh battery from China for €2400. I thought I’d get at least €1000 back for mine but see the same model at 1yo is now selling for €800 or so. I calculated a payback of 4-5 years on the incremental cost of attaching my battery. Thinking of adding a second now and electrifying some/all of my home heating with a heat pump to replace gas.

Edit to add, you don’t run specific appliances off a solar PV battery, it sits on the solar side of the inverter and the inverter takes from it when the household demands more than the solar is generating at that moment in time. Can easily boil a kettle off it, i.e. a 1.5 to 2kW draw.

 

[CharlieMac]

That's very helpful info cheers. I did a bit more reading.. Ok, I can't just buy a 15kWh battery and charge it up by plugging it in to a power socket then run a space heater by plugging it in to that same battery. I would need an inverter and maybe other things too.

There are batteries with built in inverters, but anything with decent capacity is expensive. I'm probably better off just getting solar and get a proper sized battery integrated with that.

There's a guy in my work says never get a heat pump they cost a fortune in electricity. Says a regular oil burner is more efficient. Maybe there's a way to configure a heat pump with solar to reduce the running cost.

 

[conor_mc]

There's a guy in my work says never get a heat pump they cost a fortune in electricity. Says a regular oil burner is more efficient. Maybe there's a way to configure a heat pump with solar to reduce the running cost.

Don't get me started!

Well-designed heat-pumped heating systems (importantly, system means source AND emitters/radiators AND piping) are far more efficient than an oil burner - rules of physics and all that. There are horror stories for sure, but mostly caused by inappropriately designed systems - rads too small for low flow temps, plus sometimes an old on-off mindset rather than a leave-it-running-all-the-time mindset.

Worth watching this video to see some real world results of proper HP design fixing an absolute disaster of an install.
https://www.youtube.com/watch?v=gWB27SUgoVE&pp=ygUXaGVhdCBnZWVrIHNraWxsIGJ1aWxkZXI=