My 13 secondary panels produce a max of 3.9kWh. I’m not sure how it was achieved but my installer made some adjustments (I think to the Powerwall settings) so that if my system tries to exceed 7KWh export, the secondary panels drop back to keep within the limit. If much of the generation is being used, both lots of panels will run at full steam.
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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
Agree it’s physics and not conspiracy theory, but arguably the physics could have been better had the regulators required from the network operators a different balance between shareholder dividends and investment in infrastructure.
scdoubleu
Member
MrBadger
Badger out
That's not a significant issue. I don't know what your array size is that you are planning, but on our 4kW south facing array, we don't exceed 16A for particularly long periods on not that many days a year. The biggest advantage of an oversized array is that it prolongs the usable generation window. Getting peak power is really not such a big deal as for instance, if charging your car, you can turn down and/or track the spare power - I don't even bother with that. If I need to charge, I'll extend my charge window and just accept that I will be spending a few pennys when my generation does not quite hit my demand. I get that some may want to charge their car for free at highest rate possible, but it really only adds a small financial benefit.
Days like this are very few and far between and even with 4kWp, we were nowhere near exceeding 16a. This is April, a really good month for peak power generation are panels are often nice and cool, unlike summer when they suffer with overheating which often means that peak power is less than cooler April days. The advantage of summer generation is the longer days for extended generation time, a bit like an oversized array.
Nothing clever aiding this other than 6 years generation experience of looking out of a window and knowing when to make use of the solar. I take the attitude that I charge when I need to and not when its free. The overnight charge cost 33p, and intraday charges added 11% to battery on a LR. Combined they would cover a couple of return trips that time of year - less than 35p for ~50 miles of driving. I could have topped the car up a bit more but it was at 75% and didn't need any more. Thanks to TeslaFi to remind me of that days charge, drive and battery events, graphs are from homebrew data logger and pvoutput.org.
Fast forward 8 months! Even double our capacity would make no worthwhile impact. Around £1.10 for the same ~50 miles of winter driving. So nearly 3 x the cost and nothing that solar can do about it. Its been like this for days and days and days and is the reality of our winter British weather.
This is more common of a semi decent British summer day. Only just pushing 16A (~3.6kW) but only because the panels would have a chance to cool due to clouds. We have Panasonic panels which are more tolerant of heat than most other panel chemistries.
Llama.
Lurking somewhere up North
That’s a good setup. You’ll really benefit from the battery as you will be able to cut your costs loads if you charge them up off peak. Make sure you change to an off peak tariff like Octopus Go if you haven’t already.
That’s still enough panels to run your house on a sunny day.
PITA
Model 3 Performance
We've got a 7.2kWp Solar Array, but it's split over 3 roof aspects...
10 Panels East
6 Panels West
2 Panels South
This means we get a load of Power first thing in the morning from Sunrise. This fills up our Powerwall Batteries by 11am usually.
The inverter & battery storage is fixed onto North wall outside in the shade, with ventilation. Our panels use Optimisers, which run cooler than Micro Inverters.
Summer 2022 will be better because we'll have our Tesla Model 3 plugged in, taking excess Solar... so nothing to export.
Driving the car around during the day means the Solar generated goes into the Tesla Powerwall Batteries.
Arrive back home, and charge immediately from the batteries at full 7kW power, draining them for more Solar in afternoon.
The Solar is then still topping up the batteries in the background... I can balance this by still charging the car overnight at cheap rate grid tariff if needed.
That's why Power Capability on the storage batteries need to be 10kW or more, so you can draw full EV Charge Power during the day with free Solar only, and still power the house in the background. Regardless of how much power Solar is delivering at the time.
10 Panels East
6 Panels West
2 Panels South
This means we get a load of Power first thing in the morning from Sunrise. This fills up our Powerwall Batteries by 11am usually.
The inverter & battery storage is fixed onto North wall outside in the shade, with ventilation. Our panels use Optimisers, which run cooler than Micro Inverters.
Summer 2022 will be better because we'll have our Tesla Model 3 plugged in, taking excess Solar... so nothing to export.
Driving the car around during the day means the Solar generated goes into the Tesla Powerwall Batteries.
Arrive back home, and charge immediately from the batteries at full 7kW power, draining them for more Solar in afternoon.
The Solar is then still topping up the batteries in the background... I can balance this by still charging the car overnight at cheap rate grid tariff if needed.
That's why Power Capability on the storage batteries need to be 10kW or more, so you can draw full EV Charge Power during the day with free Solar only, and still power the house in the background. Regardless of how much power Solar is delivering at the time.
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HenryT
Active Member
Thanks that's encouraging @Llama.
I actually came at this initially just after a battery (or batteries) to take advantage of the overnight rate on Octopus Go - 4 hours at 5p. We don't do enough mileage to fully use it just for the cars and 'time shifting' as much domestic use as we can - we didn't plan to have any panels as the roof is an awkward shape and faces the wrong way, too many chimneys etc. In the event, the surveyor pointed out that the garage roof would be ideal as it is a pitched roof facing south with a clear view so we have gone for that.
Yachtsman
Member
This subject has been really interesting and informative and has probably swung my decision to proceed, although I would appreciate opinions of the proposed system detailed below.
I’m currently talking to a company ( I’ve short listed from 3) about a PV system Like Henry T, I initially enquired about having a powerwall battery to keep charged using octopus go nighttime cheap rate & run the house during the evening. However all 3 suppliers recommended I add solar panels since the added cost is relatively small compared to a battery system & will contribute considerable energy during the day during summer months.
My property has 3 roofs, limited by velux windows, NE, SW & SE facing capable of 12 x 375kW panels, a total of 4.5MWp, producing 3.45MW/annum.
The components are;
12 x Eurener MEPV 375kWp HC Zebra panels
12 x SolarEdge P401 optimisers
SolarEdge energy bank 10kW (voice of 1 or 2)
1 x SolarEdge 3500H inverter
1 x optional EV charger/inverter.
This system does not provide back up in the event of power cuts.
My annual consumption including my EV is 5.8MW, averaging 7.5kW/ day.
My main interest is reducing my need for peak grid energy, not feeding the grid or a payback period. Using solar + off peak to keep the battery charged and off peak to charge the car with possible excess solar during the summer.
I would really appreciate opinions from those lucky enough to already have a PV system & fully appreciate the pitfalls of choosing the wrong system.
I’m currently talking to a company ( I’ve short listed from 3) about a PV system Like Henry T, I initially enquired about having a powerwall battery to keep charged using octopus go nighttime cheap rate & run the house during the evening. However all 3 suppliers recommended I add solar panels since the added cost is relatively small compared to a battery system & will contribute considerable energy during the day during summer months.
My property has 3 roofs, limited by velux windows, NE, SW & SE facing capable of 12 x 375kW panels, a total of 4.5MWp, producing 3.45MW/annum.
The components are;
12 x Eurener MEPV 375kWp HC Zebra panels
12 x SolarEdge P401 optimisers
SolarEdge energy bank 10kW (voice of 1 or 2)
1 x SolarEdge 3500H inverter
1 x optional EV charger/inverter.
This system does not provide back up in the event of power cuts.
My annual consumption including my EV is 5.8MW, averaging 7.5kW/ day.
My main interest is reducing my need for peak grid energy, not feeding the grid or a payback period. Using solar + off peak to keep the battery charged and off peak to charge the car with possible excess solar during the summer.
I would really appreciate opinions from those lucky enough to already have a PV system & fully appreciate the pitfalls of choosing the wrong system.
ACarneiro
Active Member
If you're based in Staffordshire, may I recommend you contact Solar Star Power?
They did my PV+Powerwall system and fitted it all in one day. Nice and knowledgeable gang and not really felt like they were trying to be pushy or feel expensive stuff "just because".
Yachtsman
Member
Thanks for the tip, but I’ve gone through the selection process over recent weeks.
I’ve settled on a company very very local to me, who are Tesla approved & have several industry awards and importantly aren’t pushy.
Costs from all three were the same within a couple of hundred although offering slightly different components.
My experience with solar panels in the UK.
I have a 30kw (3phase) array on a farm roof here.
Max peak output today has been 1.5 kw and 2.5 kwh generated total.
OK OK, yes it's a cloudy December day, however my view is, consider winter output to be almost zero in the UK.
Keep that in mind when your considering solar panels and you won't go far wrong.
I have a 30kw (3phase) array on a farm roof here.
Max peak output today has been 1.5 kw and 2.5 kwh generated total.
OK OK, yes it's a cloudy December day, however my view is, consider winter output to be almost zero in the UK.
Keep that in mind when your considering solar panels and you won't go far wrong.
Yachtsman
Member
Point taken ok winter production, I’ll depend on off peak grid hopefully.
I have very little choice when it comes to panels due to the limited and awkward roof space. I’ve got to give it to the 3 companies I have dealt with they have played with a number of different configurations & this one seems the best.
Yachtsman
Member
What size system did you get & how long has it been installed.. I started pursuing the powerwall route but 2 suppliers have suggested it maybe a little large & thus expensive for my needs.
What are your thoughts?
PITA
Model 3 Performance
How did you start the conversations around a Tesla Powerwall, and end up with a SolarEdge Energy Bank?? Anyways...
Here's my opinion
If you buy the Battery Storage & Solar Panels plus installation at the same time, the VAT should be charged at 5%. If you buy these separately, the battery kit will be charged at 20%
Your Solar Array is 4.5kWp and will be capped to a maximum power output of 3.5kW (which is your inverter size).
You should still get some decent power in Summer, with the Optimizers maximising the power output of the different roof aspects. So that all looks good.
If your house uses around 7.5 kWh of energy per day, your Solar Array will easily do this in Summer, and you'll be exporting to the Grid (or your Electric Car if you have one). I would guess your Solar Array will be producing about 30kWh on it's best Summer day. So more than enough during Summer.
You can never have enough Solar Panels in my opinion, so don't downsize
The issue you'll have is in Winter. Solar will go to nothing much in November/December/January. During this time you'll be relying on your Storage Battery, Smart Meters and a Cheap Rate Tariff (like Octopus Go).
With your storage battery you need to look at two things:-
- kW (Power Capability). This is how much maximum power your battery can discharge. This is important, because anything you use above this figure means you'll have to pull the excess from solar (non existent in Winter) or Grid Power. If you're using high power during the day, beyond the capability of your battery, then it'll be Grid Power at Peak Rate.
- kWh (Energy Capacity). This is how much energy your system can generate/store/use per hour. This is also important, because it let's you know how long your stored battery power will last.
The Tesla Powerwall has 13.5 kWh of energy capacity, and 5 kW of maximum continuous power discharge. In my opinion, that's great. Because it'll handle kettles, and toasters, and hair dryers, and microwaves, and cookers, and washing machines, and tumble dryers... plus your normal background house lights, fridges/freezers etc. All up to a maximum of 5 kW before it starts hunting extra power from the Grid (at peak rates). This means you'll mostly be using cheap rate electricity stored inside it.
If the Solar Edge Energy Bank has a 10kWh storage capacity, what is it's kW power discharge rating? (3.5kW) I don't know, please check??
That might be enough for you, but you need to consider all your electrical items in your house, and how much power they need when being used. If you never go above 3.5kW then it's all good. But if you turn on an electric shower at 8.5kW.... then 5kW will come from the Grid at Peak Rate...
Seriously consider the Tesla Gateway 2 as well. This provides backup power to your home in the event of a Grid Failure. The Gateway device also allows for EV Chargers to be wired directly to it. This means you save a Consumer Board slot.
On the Tesla Gateway device you can also wire things into it on Grid Side (so power to that item fails in a powercut, ideal if it's a pool pump or EV Charger), or it's non-grid Backup side (so power is maintained in a powercut, feeding the item from your battery power). Clever kit.
Hope that helps.
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Yachtsman
Member
Yes certainly does help, the Mk was a typo.How did you start the conversations around a Tesla Powerwall, and end up with a SolarEdge Energy Bank?? Anyways...
Here's my opinion
If you buy the Battery Storage & Solar Panels plus installation at the same time, the VAT should be charged at 5%. If you buy these separately, the battery kit will be charged at 20%
Your Solar Array is 4.5kWp (not 4.5MWp) and will be capped to a maximum power output of 3.5kW (which is your inverter size).
You should still get some decent power in Summer, with the Optimizers maximising the power output of the different roof aspects. So that all looks good.
If your house uses around 7.5 kWh of energy per day, your Solar Array will easily do this in Summer, and you'll be exporting to the Grid (or your Electric Car if you have one). I would guess your Solar Array will be producing about 30kWh on it's best Summer day. So more than enough during Summer.
You can never have enough Solar Panels in my opinion, so don't downsize
The issue you'll have is in Winter. Solar will go to nothing much in November/December/January. During this time you'll be relying on your Storage Battery, Smart Meters and a Cheap Rate Tariff (like Octopus Go).
With your storage battery you need to look at two things:-
- kW (Power Capability). This is how much maximum power your battery can discharge. This is important, because anything you use above this figure means you'll have to pull the excess from solar (non existent in Winter) or Grid Power. If you're using high power during the day, beyond the capability of your battery, then it'll be Grid Power at Peak Rate.
- kWh (Energy Capacity). This is how much energy your system can generate/store/use per hour. This is also important, because it let's you know how long your stored battery power will last.
The Tesla Powerwall has 13.5 kWh of energy capacity, and 5 kW of maximum continuous power discharge. In my opinion, that's great. Because it'll handle kettles, and toasters, and hair dryers, and microwaves, and cookers, and washing machines, and tumble dryers... plus your normal background house lights, fridges/freezers etc. All up to a maximum of 5 kW before it starts hunting extra power from the Grid (at peak rates). This means you'll mostly be using cheap rate electricity stored inside it.
Seriously consider the Tesla Gateway 2 as well. This provides backup power to your home in the event of a Grid Failure. The Gateway device also allows for EV Chargers to be wired directly to it. This means you save a Consumer Board slot.
On the Tesla Gateway device you can also wire things into it on Grid Side (so power to that item fails in a powercut, ideal if it's a pool pump or EV Charger), or it's non-grid Backup side (so power is maintained in a powercut, feeding the item from your battery power). Clever kit.
Hope that helps.
As the owner of a M3 I initially looked for a Tesla approved supplier & wanted to go down the powerwall 2 route with SolarEdge optomisors & have two proposals for such.
Two of the suppliers suggested that maybe a powerwall was an overkill for my small system and relatively light use & that there are smaller cheaper storage options. Maybe they thought offering me a cheaper system would trigger me to place an order, knowing they were not the only company bidding.
Although we are both retired our daytime consumption until 4.30ish is relatively light except for the odd kettle, a AA+ rated dishwasher 3 times a week & A+ washing machine. None of those are used during off peak. The 7.5kW is obviously excluding the EV.
I’ve not had a costing for the SolarEdge system yet since I need to decide if it’s 1 or 2 batteries & for that decision I hoping for advice from this forum.
I’ll have to enquire whether a Tesla gateway 2 will fit with the proposed system. I suspect (although not itemised) the powerwall proposals included the gateway.
A single battery will give me 3.5kW discharge capacity which to me will be I suffice to & will need help from the grid at times.
I understand Inwill need to change my EV wall charger to enable charging from the battery.
I wonder if anyone has any knowledge of the proposed panels.
MrBadger
Badger out
Somehow I ended up on Solar Edges installer list. It was very enlightening how sales were being 'pushed'.
Don't get me wrong, Solar Edge is great stuff, I have it myself and would buy it again. But optimisers are there to solve shading problems and difficult arrays, not to boost output on otherwise good installations. The 10% or whatever benefit they use to say (no idea what they quote these days) is a 10% recovery of the losses due to constrained arrays. They won't give you anything on a good array and very little benefit on a well designed a constrained array. It was always glossed over as a saving and not a saving on losses. A well designed constrained array can also give almost optimal performance should the conditions allow, but unfortunately many installers do not take the time to properly design a system (often their initial design is based on a satellite view of the property and not further refined after an onsite survey) and instead take the optimiser (or micro inverter) route as its easier and offers more of a financial incentive.
Yachtsman
Member
I’ve got to admit every supplier pushed SolarEdge optimisers as the only way. You are right in that two of the suppliers have not visited site, whereas the local co have, however their price will depend ultimately on a full site survey, rightly so, I don’t want any nasty surprises halfway through installation.
What are thoughts on 1 x 10kW battery with 3.5kW output. Here is a typical usage graph excluding EV.
What are thoughts on 1 x 10kW battery with 3.5kW output. Here is a typical usage graph excluding EV.
Attachments
PITA
Model 3 Performance
Yeah, your use is very low. In fact so low, all your new solar & battery kit is more for your EV Charging I guess.
Compare it to our house
Last week our average daily use was 60 kWh... nearly 10 times your daily average... even more the week before.
Since we moved all-electric our use has quadrupled...
Compare it to our house
Last week our average daily use was 60 kWh... nearly 10 times your daily average... even more the week before.
Since we moved all-electric our use has quadrupled...
Attachments
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