Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

What do you do with your excess solar power?

Llama.

Member
Jan 25, 2021
178
88
Leeds, UK
For those of you with solar panels, what do you do with your excess solar power?

Ive returned from a 190 round trip journey to the Lake District in my M3 Long Range and it’s all charged up again from solar power after a couple of days. The battery storage system is topped up too. I’ve got the immersion heater on and it’s up to temp now. Octopus tariff has been optimised.

Im sitting like a geek staring at my Zappi display showing 2.5 kWh of excess solar just slipping back into the grid. Over 27 kWh exported this month already!

Is there anyone else out there feeing like you need to put a load of wash on or put a jacket potato in the oven for lunch to use up your solar power?

Or am I better just giving it to the grid for free as part of some contribution to offsetting our nation’s carbon footprint?
 
  • Like
Reactions: Neilio

GlynG

Member
Apr 26, 2021
40
80
Wigston, Leicester
I assume your displeasure at giving back to the grid means you don't have a fit tariff?

I only use the 13 amp socket charger on mine but connected to a Hive Smartplug - When my solar has fully charged my home batteries (13.5Kw) I activate the smartplug to send the excess power to the car, If the car has reached its full charge (90%) then i will increase the house consumption - so a wash will go on, the tumble dryer, start cooking / baking etc, Get every battery charger charging up the power tools/lawnmower etc.

I dislike giving energy back to the grid but sometimes its unavoidable and with a FIT tariff I an getting paid a few pence for each KW I generate in total plus a few more pence for 50% of the generation as deemed export.

I would like to add more home batteries but you have to draw the line somewhere
 
  • Informative
Reactions: Jez_GB

Mrklaw

Member
Mar 5, 2020
398
207
Berkshire
honestly if you're all topped up including a big car battery, home battery and water, in this relatively poor May, and only exported 27KwH 2/3 the way through the month, I think that's just about as optimal as you can get before you start doing as GlynG mentions
 

Llama.

Member
Jan 25, 2021
178
88
Leeds, UK
No, not lucky enough to have a feed in tariff. That would be great..

Yes 27 kWh isn’t that much to export, but it’s frustrating that I’ve actually imported / purchased almost 100 kWh in the same time. Albeit at off peak rates.

But still…

That’s my 27 kWh of electricity. I made it!

I will admit to being tempted to put the kettle on for a cup of tea, but I draw the line at using the tumble dryer on sunny days. The laundry has to go on the line.
 
Last edited:

Dilly

Active Member
Feb 24, 2020
1,871
1,533
Norfolk
May has been a bit poor. I’ve generated 590Kwh. Exported 121Kwh. Drew 3Kwh from the grid (Powerwall balancing)
charged both cars, two Powerwalls and ran the dishwasher daily. Tumble dried the washing, Ran the electric floor washer and did a pyroclastic clean on the oven every week. Charged up the new bikes yesterday.
my 7Kw array gets FIT and export payment but not the 3.9Kw array which shuts down if export occurs.
i can’t help but export sometimes and we haven’t even hit a 60Kwh day yet!
 

Llama.

Member
Jan 25, 2021
178
88
Leeds, UK
I’m on Octopus Go for cheap off peak grid usage. I don’t think I make enough solar with my 4.2 kw PV system to justify the switch to Agile.

So I just tank up my battery at cheap times
 

Dilly

Active Member
Feb 24, 2020
1,871
1,533
Norfolk
I’m on Octopus Go for cheap off peak grid usage. I don’t think I make enough solar with my 4.2 kw PV system to justify the switch to Agile.

So I just tank up my battery at cheap times
Agile is too much like hard work to me. Is the further saving enough to spend time on. In my case I doubt it.
 
  • Like
Reactions: Llama.

LukeUK

Member
Feb 25, 2020
379
226
Shropshire, UK
Mostly run the immersion heater in the hot water tank. In summer, I change the boiler timing to only come on after sunset, and the thermostats are staggered, so it means that the boiler hardly runs for about 4-5 months of the year.

I've pretty much given up charging from solar, unless it's a completely cloudless day. My 3 kWp array means that there's only a couple of hours in the middle of the day when it will consistently produce enough power to get the charging current, and efficiency, up on the car, and all it takes is a cloud, then the 6A minimum means that I'm paying a lot, compared to the 5p/kWh that Go offers.

With so much working from home over the last 18 months, we now run the dishwasher, washing machine, etc over lunchtime, so that makes better use of the PV, and the immersion heater soaks up the rest.

I can't get the maths to offer anything like sensible payback on batteries, so that will have to wait for a while.
 
  • Like
Reactions: Llama.

Gatsojon

Member
Aug 4, 2019
627
609
Manchester UK
I’m on the Tesla plan currently so get 8p per kWh for feeding back. I still prefer to use the spare electricity if I can but that’s not been possible with such low mileage. We are at least helping in a small way to decarbon the grid.
 
  • Like
Reactions: Jez_GB

Dilly

Active Member
Feb 24, 2020
1,871
1,533
Norfolk
Mostly run the immersion heater in the hot water tank. In summer, I change the boiler timing to only come on after sunset, and the thermostats are staggered, so it means that the boiler hardly runs for about 4-5 months of the year.

I've pretty much given up charging from solar, unless it's a completely cloudless day. My 3 kWp array means that there's only a couple of hours in the middle of the day when it will consistently produce enough power to get the charging current, and efficiency, up on the car, and all it takes is a cloud, then the 6A minimum means that I'm paying a lot, compared to the 5p/kWh that Go offers.

With so much working from home over the last 18 months, we now run the dishwasher, washing machine, etc over lunchtime, so that makes better use of the PV, and the immersion heater soaks up the rest.

I can't get the maths to offer anything like sensible payback on batteries, so that will have to wait for a while.
I forgot in my post that the hot water heats on solar too.
there is no sensible payback on batteries. It’s the convenience of having a buffer for when solar is intermittent, running the house/car charging overnight and backup for power cuts.
 

Gatsojon

Member
Aug 4, 2019
627
609
Manchester UK
Mostly run the immersion heater in the hot water tank. In summer, I change the boiler timing to only come on after sunset, and the thermostats are staggered, so it means that the boiler hardly runs for about 4-5 months of the year.

I've pretty much given up charging from solar, unless it's a completely cloudless day. My 3 kWp array means that there's only a couple of hours in the middle of the day when it will consistently produce enough power to get the charging current, and efficiency, up on the car, and all it takes is a cloud, then the 6A minimum means that I'm paying a lot, compared to the 5p/kWh that Go offers.

With so much working from home over the last 18 months, we now run the dishwasher, washing machine, etc over lunchtime, so that makes better use of the PV, and the immersion heater soaks up the rest.

I can't get the maths to offer anything like sensible payback on batteries, so that will have to wait for a while.
I tried many ways to justify my Powerwall 2 financially and all failed. In the end I decided I’d have it cos I wanted it and I have no regrets.
 

Drew57

Active ember
Apr 4, 2020
1,066
1,264
Chester UK
We plug the car in with a 90% max setting, leave the Zappi charger on Eco+ & that then tops up whenever there is sufficient surplus from the following:

  • Background house demand
  • House batteries filled to +95% (Zappi then continues to charge car as long as an overall +1.4kWh spare is available)
  • 5L hot water heater (for drinks 'on-tap')
  • Washing machine
  • Tumbledryer
  • Dishwasher
  • Battery charged lawnmower
(All except house batteries have a timer facility)

Not all are used every day & there are additional things like baking/cooking which often happen during a high solar period.

Note: In addition, during summer I sometimes boil sufficient water to pour on the patio/drive wherever weeds/moss have appeared & it does just as good a job as weedkiller. I've been known to use several 'free' kW in this way & it's pretty effective - moss turns brown & permanently dies, water seeps into cracks & kills smaller weeds right down to the roots, With care this works on areas of a flowerbed too where multiple small weedlings appear (...who would have thought someone would post this sort of stuff on a Tesla forum?! :eek:)
 

GlynG

Member
Apr 26, 2021
40
80
Wigston, Leicester
The case for home battery's? - I'm not sure if financially they make sense or the purchase was my Man maths kicking in with a desire to have them rather than need them because whilst there is a 10 year guarantee on them no one really knows just how long they will last. If they only last for 10 years then perhaps I will be close to break even - If they go on for 15 plus years then they were a super investment.

In my head (Man maths again) fingers crossed for 15 years and by then battery technology will have substantially improved and prices dropped - of course like many things in life - what seemed like a sufficient amount (KW capacity) now, you can be sure the density will rise and instead of looking like for like I would be looking for a lot more storage capacity.

I bought my first battery 4.5Kw with the solar so only paid 5% VAT on it - now you have to pay the full 20%. I added a further two 4.5Kw batteries and that is the maximum my system can handle (Solax triple power) - though initial advertising indicated 4 batteries could be linked - so i do feel a little cheated - but thats life.
I have a 12 LG Neon R panels (365 watts each) and an optimiser on every panel with 25 year guarantee on production and construction and my best day in the two and a half years they have been fitted is 34Kws - which I'm very pleased with, The house demand is about 14 Kws per day - so even on dull days I rarely have to pay for electricity - thought the wife is a very efficient waster with pretty much everything.

I'm retired so I can make full use of Solar and batts and my mileage is low - so the 2KW charger is perfect for me to keep the car battery charged and not draw from the grid. If I only bought things that made financial sense I would be living in a cave - my heart tends to overrule my head - a condition I'm very happy with.
 

Tony Hoyle

Active Member
May 7, 2019
1,072
659
Stockport, UK
I just feed back to the grid. This week I've exported 15Kwh.. it's tiny amounts on any given day, mostly available when I'm at work.. so might as well let the grid do something useful with it.

I used to heat an immersion with it but have since chucked the boiler installed a combi which is significantly cheaper to run even taking into account the solar heating.
 
  • Like
Reactions: VanillaAir_UK

Llama.

Member
Jan 25, 2021
178
88
Leeds, UK
We plug the car in with a 90% max setting, leave the Zappi charger on Eco+ & that then tops up whenever there is sufficient surplus from the following:

  • Background house demand
  • House batteries filled to +95% (Zappi then continues to charge car as long as an overall +1.4kWh spare is available)
  • 5L hot water heater (for drinks 'on-tap')
  • Washing machine
  • Tumbledryer
  • Dishwasher
  • Battery charged lawnmower
(All except house batteries have a timer facility)

Not all are used every day & there are additional things like baking/cooking which often happen during a high solar period.

Note: In addition, during summer I sometimes boil sufficient water to pour on the patio/drive wherever weeds/moss have appeared & it does just as good a job as weedkiller. I've been known to use several 'free' kW in this way & it's pretty effective - moss turns brown & permanently dies, water seeps into cracks & kills smaller weeds right down to the roots, With care this works on areas of a flowerbed too where multiple small weedlings appear (...who would have thought someone would post this sort of stuff on a Tesla forum?! :eek:)

I love the boiling water weed killer suggestion!
 

Mattallica

Member
Apr 2, 2021
137
97
Durham
We plug the car in with a 90% max setting, leave the Zappi charger on Eco+ & that then tops up whenever there is sufficient surplus from the following:

  • Background house demand
  • House batteries filled to +95% (Zappi then continues to charge car as long as an overall +1.4kWh spare is available)
  • 5L hot water heater (for drinks 'on-tap')
  • Washing machine
  • Tumbledryer
  • Dishwasher
  • Battery charged lawnmower
(All except house batteries have a timer facility)

Not all are used every day & there are additional things like baking/cooking which often happen during a high solar period.

Note: In addition, during summer I sometimes boil sufficient water to pour on the patio/drive wherever weeds/moss have appeared & it does just as good a job as weedkiller. I've been known to use several 'free' kW in this way & it's pretty effective - moss turns brown & permanently dies, water seeps into cracks & kills smaller weeds right down to the roots, With care this works on areas of a flowerbed too where multiple small weedlings appear (...who would have thought someone would post this sort of stuff on a Tesla forum?! :eek:)

I bet the neighbours think you've boiled some brutal Porton-Down mixture!

I wonder if that works on Ground Elder...
 

Drew57

Active ember
Apr 4, 2020
1,066
1,264
Chester UK
I bet the neighbours think you've boiled some brutal Porton-Down mixture!

I wonder if that works on Ground Elder...
My neighbours probably view me as some sort of eco-nut & the one opposite would even remove the word eco from that.

A couple of years ago on solar but using a corded mower, I was cutting the lawn as usual.... just as full batteries were due to force grid export. I had earphones in & was enjoying some very loud rock music but hadn't noticed that same neighbour standing with arms folded watching me with a puzzled expression.

After I had made about five passes across the lawn I realised that I couldn't feel any vibration in my hands - the plug had pulled out a couple of minutes earlier & I was happily taking the silent & lifeless mower for walkies back & forth, back & forth :mad:

(...some music really IS that good!)
 
Last edited:

Country Boy

Member
Oct 8, 2020
80
32
Herefordshire
I have a power wall and a deemed export of 50% of all I produce. It doesn't matter if I send juice back to the grid or not, I still get paid the same..... So

I have a series of electric heaters on remote controlled plugs. If it looks like I am going to start exporting, I turn on a heater or 2. It reduces the fossil fuel I burn for heating the house, and costs me zero. I have used more than 150kWh this way this year.

This works well in the spring when temperatures are low and sunlight (usually) good. This does not work in the summer or autumn, but then I can use the solar to power a portable aircon unit.. OMG I never realised just how much juice those things use!!! More than a heater!

It is not that I am an obsessive, but I do spend much more time than is healthy looking at the power wall app...
 
  • Like
Reactions: Tattersky

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top