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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
Pink Duck
Active Member
Just noticed my PV proposal forecast for August was 30 kWh falling to 20 kWh daily average, the reality from smart meter nearer 42 kWh daily.
Probably installer system being on the conservative side of things. Total of 1,280 kWh exported, £72 net bill credit.
Probably installer system being on the conservative side of things. Total of 1,280 kWh exported, £72 net bill credit.
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Chimpy McChimp
Member
I'm currently fixed at 19.23p per kwh 20.67p standing charge. That's a flat rate until next year. No off peak. I haven't looked around much but I suspect I won't get better.
Even if I only get a few pence in my pocket for export it might buy a couple of beers or coffees. Better in my pocket than anyone else's. But Scottish power seem to be a bit of a *sugar* show based on that MSE forum thread.
WannabeOwner
Well-Known Member
I've switched from "Mid-Summer mode" where I play Rusian Routlet of trying to have the Powerwalls fall to 0% just as sun PV exceeds household usage (which is an expensive game to get wrong because failing to predict an overcast / "poor PV" day, just once-or-twice in the Summer, loses me all my gains ...)
... so now switched to Autumn Mode in which I assume that I am unlikely to have enough excess to charge the cars, so rather than charging the cars on Off Peak I charge the PowerWalls on Off Peak (e.g. 50% - even 100% if tomorrow's weather looks "poor", let alone "Shiite") and then that guarantee that I don't run out during the day ... and if it is actually sunny the excess will go into the cars. If the cars fall below 50% they will charge "a bit" on Off Peak. I suppose if the cars got to Full Tank I'll have to think again, but that hasn't been the case for the last couple of weeks
whole time since installation, I was playing with:
a) Solar will cover the house, batteries will be topped up.
b) I will charge my car at night but about 10% less than usual (I like to have 80% SOC every morning). and I will stop discharge of battery if IO is enabled. if car is charging and my battery is set for charging, I set the max amount my battery can charge from AC to 50% at the moment.
c) I will top up with any excess power to my car - usually those 10% on around 10-11 A power.
I still need to play around with logic.. but what I really want to know is how to set up Home Assistant with IO, Growatt and Tesla that once my schedule for IO is set up - then HA automatically set the Growatt to battery first :/
anyone got ideas?
a) Solar will cover the house, batteries will be topped up.
b) I will charge my car at night but about 10% less than usual (I like to have 80% SOC every morning). and I will stop discharge of battery if IO is enabled. if car is charging and my battery is set for charging, I set the max amount my battery can charge from AC to 50% at the moment.
c) I will top up with any excess power to my car - usually those 10% on around 10-11 A power.
I still need to play around with logic.. but what I really want to know is how to set up Home Assistant with IO, Growatt and Tesla that once my schedule for IO is set up - then HA automatically set the Growatt to battery first :/
anyone got ideas?
Chimpy McChimp
Member
Ooft. You guys are way ahead of me. I just got to a point where I figured "hang on, I'm covering house usage and filled battery by 1pm. Best get car charging!"
Still trying to get even that right. It's been very sunny here the last couple of days so plugged car in and reduced amps for the sun to disappear behind a cloud and I started drawing from the grid.... Sigh.
I'd love to see a day where my grid draw is nothing (or minimal) and Im not exporting for nothing/a pittance.
Ever the optimist.
Still trying to get even that right. It's been very sunny here the last couple of days so plugged car in and reduced amps for the sun to disappear behind a cloud and I started drawing from the grid.... Sigh.
I'd love to see a day where my grid draw is nothing (or minimal) and Im not exporting for nothing/a pittance.
Ever the optimist.
Drew57
Active ember
Doesn't happen with a Zappi though - zero manual intervention to charge the car & nothing draws from the grid regardless of sun or cloud or both.
Chimpy McChimp
Member
Sounds great. I have the Tesla charger. No real reason, just was naive and bought It when I ordered the car. That said. Back then I didn't know I was going to get solar and battery installed.
I just looked at my energy hub and noticed a couple of days this week my electricity usage from grid was 75p. So I've not quite got to £0.00 yet (nor am I likely to at this time of year I suspect) but it's a lot better than before the solar and battery.
Chimpy McChimp
Member
I am aware of the standing charge. I was meaning my usage
Ok so I will never get to £0.00. But it's great to see my usage going from maybe £3-4 a day to under £1.
I know not every day will be like that. But hoping to see some very good savings over the year
I'll need to get cleverererer than I am now when I have to change my tarrif and get on a cheap overnight rate.
I'll put my zappi on eco mode so it'll keep going even when the sun goes in, but drop down to 1.4kw (same as dynamically lwoering the amps). The battery covers those downturns as long as I'm confident the sun will top it back up again later.
I'm with Scottish Power for export. Took maybe 8 weeks. I have a solar battery system and just sent them a scan of the schematic from my installers handover brochure. Only pence I know but now letting excess solar go to grid at 12 p/kWh rather than putting it in the car which I can charge overnight at 7.5 p/kWh on IO
Since I had my Powerwall installed in April to complement the solar for which I am lucky enough to get FIT I have not used any peak time power. At an off peak rate of 4.5p which sometimes charges the cars and occasionally tops up the Powerwall my biggest expenditure on electricity by far is the standing charge of just over 50p. It may be different in winter with less solar input but I am still chuffed to bits with the system, which has put me easily in profit since April (if you ignore the initial investments,although solar paid for itself in 7 years).
Chimpy McChimp
Member
Did you get asked for the DNO confirmation reference number (starting ENQ or NC?) When you applied?
phil4
Member
Yep, I've got some automation in place using HA.
It uses SolCast scaled to 70% efficiency on their end, which has been close to my actual output.
Then run an automation during IO cheap rate, about 5 times, an hour or apart, checking the forecast, and setting the reserve on the battery. The reserve is set by a formula which turns the predicted solar value into a battery percentage... high solar, lower battery etc. This will then either dump excess into the car charging at night, or charge from the grid to get to it's target (while the car is charging).
Once out of IO set the battery target back down, so it receives solar.
Then in the afternoon if the battery is approaching 100%, start the car charging, which occurs at 1.5kW. This usually leaves the battery able to accept solar until the end of the day.
I've also got a couple of automations for IO outside the standard period (which hasn't happened much), it sets the battery target to it's actual current level, so no charge or discharge and lets the car get on with it, and then returns the battery target back down when the IO period has ended. With this watch out as Octopus IO API will report an intelligent slot until 05:32... not 05:30, so you could charge car/battery in that 2 mins, at peak rate (as they do charge it at that).
phil4
Member
All "hand coded", and it's a couple of tesla powerwalls as the battery. Here's an example of the Solcast rule in YAML:
trigger is the times it runs.
action kicks off a solcast update, then waits 1 minute.
Then calls the number set service, value being that formula I mentioned. The device being the device ID of the powerwall.
Happy to share any others, but I suspect with different batteries and the like you may need to tailor to suit your needs.
WannabeOwner
Well-Known Member
This has come up before, so I'm just recapping.
I have a Zappi, but I (now) think this is the wrong approach (of charging car when Export is detected ... and having a mode for "Keep charging at low AMPs when sun goes in - which might be lunchtime, and for the rest of the day ...)
My preference is for "something" to detect that export is occurring and start charging the car.
That can take into account the rate at which the battery is filling - my PV will generate more power than the car can take, so if battery fills and then export to car starts there will still be export. So I need battery to fill and car to charge at same time (when PV is generating those sorts of high numbers, and Solcast is predicting good sun)
I want car to charge when battery gets to, say, 95% and then keep the battery in the 95% - 100% zone (by altering AMPs), rather than (potentially) toggling charging on/off - which is not great for the contactor.
This approach also just needs a dumb charger, and any flexibility / customisation that is required is in the API APP. More upgradable if the Author / customer-feedback has any additional brainwaves
