What should I expect from a 4kw system

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Andy1733

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Hi all. I'm in the process of fitting solar PV. As I mentioned on the other thread I'm fitting 15 X 255w panels South facing with no shading. Inverter is a 3.6kw Solis hybrid. I intended to add a 5-10kw (ish) battery backup in the next few month (funds depending)

My supplier ATM is EDF and according to the EDF meter app I have a base line of energy use.

This baseline usage from approx 11pm to 6am is I'm guessing when I'm asleep.. I've done a AVG over the past 2 month and it's 0.55kw per hour.

I presume I have this same baseline usage through the day though it's more difficult to asses due to additional daytime usage..
I have a koi pond with air and water pumps plus fridge/freezers running 24/7 add to this my standby items so I guess this is where my min baseline usage comes from.

My hope is the system I'm fitting will cover at least this base line figure. Am I being realistic? Will the system be enough?
If not, What should I add to meet this min?
 

binky

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you have 3375kW of panels so that should generate around 3375kW of leccy over the year, possibly a bit more depending on roof pitch and your exact location in the UK. You should get the majority of your leccy for around 2/3rds of the year from your system / batteries provided you are smart about using it. ie set appliances to work at peak times of day, watch the weather forecast etc etc. Having batteries makes it far less necessary to watch the weather, but it's still worth doing this. Your Solis can be connected to an on-line portal via a dongle which will really help you max the gains from your system.
 

Andy1733

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Quick update from my 3.6kw set-up

I finished the install on the 19th may except the battery which are still on order

So figures from 20th may to 20th June (1 month) the figures are

solar power generated 496kwh
Self use 278kwh
Sent back to grid 218kwh.

Total Power consumed 531kwh
Imported from the grid 253kwh

Peak gen per day 24.4kwh
Low gen per day 6.1kwh
 

binky

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Quick update from my 3.6kw set-up

I finished the install on the 19th may except the battery which are still on order

So figures from 20th may to 20th June (1 month) the figures are

solar power generated 496kwh
Self use 278kwh
Sent back to grid 218kwh.

Total Power consumed 531kwh
Imported from the grid 253kwh

Peak gen per day 24.4kwh
Low gen per day 6.1kwh
Sounds pretty good, what's the roof pitch and orientation
 
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I agree, not bad figures. Your winter poor light months will depress you.

I think depress is a bit harsh. Its winter the sun doesn't shine much from November to March so anything is a bonus and for us last year - April was the sunniest:), the previous year it was May :) and this year June is just going to beat May
 

binky

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I agree, not bad figures. Your winter poor light months will depress you.
the last 2 years have been particulalry bad, it seems climate change is making winters much warmer, but that is also giving us lots of cloudy gloomy overcast weather which is awful for the solar outputs.
 

Gian

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I think depress is a bit harsh. Its winter the sun doesn't shine much from November to March so anything is a bonus and for us last year - April was the sunniest:), the previous year it was May :) and this year June is just going to beat May
Huge smiles on my face this time of year. Free ev charging home battery's charging to 100% everyday, and a lovely fit payment.
 

Andy1733

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Tbh once I get the battery, if I can cover my baseline (12kwh) for 8 month of the year I will be chuffed. Esp for a system under 5k.
Looks highly likely when the price increase comes in October that payback will be around 4 years.
 

Chrisbee

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Huge smiles on my face this time of year. Free ev charging home battery's charging to 100% everyday, and a lovely fit payment.
Could you expand on the free EV charging please? (Does this need its own thread?)

I have Solar PV with 4.8kWh Li-Po batteries and a hot water diverter.

My EV charging is only via 13A socket at present. 2015 Nissan Leaf 30kWh battery.

EV takes a steady 2.6kW for hours on end, (12 if it's empty). PV output is up and down with every cloud that passes, house battery looks after the dips nicely and is always full by sundown this time of year. Unless the car is on charge.

My max ever daily PV production was 30kWh but that's very rare. We use say half of that in the house anyway. So a good proportion of car charging has to come from the grid.

Is there a smart way (charger?) to divert excess solar to the car?
 

Chrisbee

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Absolutely it is but at the moment that's a manual process that most often empties the house battery.

I'd swap the water diverter for an EV equivalent. I guess if they're available then they're not going to be cheap?
 

Chewbacca

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Absolutely it is but at the moment that's a manual process that most often empties the house battery.

I'd swap the water diverter for an EV equivalent. I guess if they're available then they're not going to be cheap?
This may suite your needs
 

Chrisbee

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Interesting, many thanks. Worth looking into. On a purely cost saving basis it would take a long time to pay for it's self. But it does appear to do what I'm asking.

Hopefully I'd be able to have a priority list. Solar generated power to house first, house battery next, then EV and lastly water heating.
 

binky

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Interesting, many thanks. Worth looking into. On a purely cost saving basis it would take a long time to pay for it's self. But it does appear to do what I'm asking.

Hopefully I'd be able to have a priority list. Solar generated power to house first, house battery next, then EV and lastly water heating.
it may be worth looking at EV tariffs on offer from the likes of Octopuss, then target daytime use and battery for the house to offset higher daytime charges, and charge car at night
 

Chrisbee

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I like this idea. Although, I'm on a fixed 21.5p tariff until end Dec 2023. Which I understand is pretty darned good and will be even more so after an October price hike?
 
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