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Solar PV and battery

 
Solar Photovoltaic (PV)
Last Post by atommyk 3 years ago
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 batalto
(@batalto)
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Joined: 4 years ago
Posts: 1091
Topic starter 26/04/2021 9:20 am  

Hi all,

Just to let people know we have reached the milestone (in early April) of being now almost totally off grid from our PV and battery system. Over the last few days we now buy token amounts of power, on the 24th we bough 0.08kw. Most of the power we buy stems from the fact that our system has a max output from the battery of 3kw. If we turn on a few power heavy appliances oven, cooker, tumble dryer at the same time we are basically forced to buy power from the grid. This tends not to be an issue later in the day as we have sunlight longer now.

The only issue we will have is rainy, cloudy days.

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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 atommyk
(@atommyk)
Eminent Member Member
Joined: 3 years ago
Posts: 12
09/03/2022 2:43 pm  

I've just come across this post as I'm trying to catch up on solar PV (had some quotes now) and gather you must be feeling rather chuffed with yourself given the current energy prices 😉 I'm looking into an ASHP plus solar as well, but as we might have to do that in steps, solar PV would be first.


   
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 batalto
(@batalto)
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Joined: 4 years ago
Posts: 1091
Topic starter 09/03/2022 3:50 pm  

@atommyk now we have the ASHP it's going to be a little different as that chews power. However it's good that we are basically free on the bulk of our power and heating as long as it's a clear day.

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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 atommyk
(@atommyk)
Eminent Member Member
Joined: 3 years ago
Posts: 12
09/03/2022 3:52 pm  

Ah fair enough, I wondered how you had achieved that with ASHP on a 8.4kW system in a house that's got a much larger footprint than ours 🙂 But I've only just started going down that rabbit hole...


   
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 batalto
(@batalto)
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Joined: 4 years ago
Posts: 1091
Topic starter 09/03/2022 4:55 pm  

@atommyk don't get me wrong, we are well down now on power use. Our batteries are full and much of the excess PV is heating our hot water at the moment. I imagine we'll make it to the low rates this evening before we buy any power.

It's why I'm considering more batteries at the moment. If you do go that way, just make sure you get a good hybrid inverter that's battery capable. Or you'll have to buy a new one down the line!

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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 atommyk
(@atommyk)
Eminent Member Member
Joined: 3 years ago
Posts: 12
09/03/2022 5:16 pm  

@batalto thanks that's really useful. I was definitely going to install a battery (currently considered 5 kWh for a 4-5 kW system) so the inverter would be hybrid from the start - correct? As any quotes should provide the correct inverter, and as I understand it, attaching further batteries would then not be a big issue? 

FYI, the best quote for 11x400W panels, 5kW inverter and 5.2 kW battery was around £8.7k which I understand would have been quite a bit cheaper last year (I gather the companies would have adjusted their quotes upwards too to reflect rising energy prices and therefore the margin for them could be greater...).

Looking forward to the heating engineer visit next week to give us a better idea of ASHP options in our house...sounds amazing that you can go into the evening with full batteries on a sunny day in March! 


   
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 batalto
(@batalto)
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Joined: 4 years ago
Posts: 1091
Topic starter 09/03/2022 5:23 pm  

What's the split on batteries and solar? I'm looking at buying in some batteries for $240/kWh from China. Just check your inverter can work with multiple batteries. Some might be proprietary if they are packaged from a supplier.

Screenshot 2022 03 09 16 21 15 95 55ef112fdffe44c65de534f40acb2de5

This is today - you can see the batteries being filled overnight and then since then, basically nothing purchased.

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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 atommyk
(@atommyk)
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Joined: 3 years ago
Posts: 12
09/03/2022 6:15 pm  

@batalto Yeah if I knew the split...they haven't split the quote up I'm afraid! I will make sure to add this to the list of questions re the inverter. 

 I see, you filled the batteries on the cheaper night tariff and then used throughout the day...for a moment, I thought you had managed to generate so much on your panels that your panels were full 🤓  


   
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 batalto
(@batalto)
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Joined: 4 years ago
Posts: 1091
Topic starter 09/03/2022 8:19 pm  

@atommyk once the heat pump was installed that was always our plan. Saved us a tonne of cash so far - hence the thinking on bigger and more batteries. With 4kw of panels you'll easily fill a 5kwh battery. From my experience, double your estimate lol

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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 batalto
(@batalto)
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Joined: 4 years ago
Posts: 1091
Topic starter 10/03/2022 10:48 am  

@atommyk got pretty close yesterday to not using peak power

image

Take off 3kw from anything "to grid" which gets dumped into my hot water tank via a Solic

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE


   
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4
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 atommyk
(@atommyk)
Eminent Member Member
Joined: 3 years ago
Posts: 12
10/03/2022 4:44 pm  

Nice work and thanks for sharing batalto! Have reached out to a few more companies for quotes, will keep you posted on how that's going.


   
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