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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
Discharge rate is almost the same too as I assume those numbers are per unit? 4x25 vs 3x37? A little extra oomph from the 3 big ones. At the internal 48v you are getting 5.3kw over 4.8 which would seem a useful increase for free.
My 3kw isn't really enough for pure battery operation. Bit of support from PV or grid and it's fine tho.
Yes, definitely set up independently as the Gen1's weren't behaving like this. It's likely there is some AC monitoring in the Gen2 firmware that maybe causing the issue, but like you said not ideal because of the losses but also unnecessary phantom cycling of the batteries.Thanks for that explanation. Very interesting.
So they were independent on the Gen 1’s but now somehow they can cross charge with the Gen 2’s. Presumably that’s to do with the Gen 2’s BMS firmware. Or the inverter firmware?
So for either or both inverters to now charge one battery or the other, they must both be connected to both batteries or it sounds more like one is discharging back through its inverter to the consumer unit to charge the other one (which would incur conversion losses.) Or more likely, could it just be that one inverter is charging one battery and the other inverter is not charging it’s battery and just putting the power to the consumer unit which is then charging the other battery? Either way sounds non-ideal.
Ideally they should charge non-evenly from the respective inverter and then do that when one of the batteries get full only. That would be most efficient.
Does this happen with all set ups like this or just a few?
Keep us all updated if anything changes.
My understanding is all set ups with hybrid Gen2/AC inverters.
scdoubleu
Member
Larger is certainly better if you want to improve your chances of staying off grid at peak-rate, but the law of diminishing returns applies.@scdoubleu any advice regarding batteries? Larger is better I suppose?
I did consider having a second Powerwall (not possible anyway thanks to DNO edict) but the economics don't add up for our current usage. The ROI would be pushed out way beyond the warranty on the installation. This will change if/when we ditch the 25 year-old gas boiler for a heat pump solution some time down the line. At that point a second (or third) Powerwall (or equivalent) will make much more sense financially, DNO permitting of course.
Right now our house usage idles at around 360 Wh per hour overnight, rising to around 500 Wh per hour during the day. A single Powerwall is quite capable of handling that during the 20 hours of peak rate, with some left over for cooking. On poor solar days, immersion heater and dishwasher run overnight. So even in the darkest days of winter we rarely use peak rate grid - I counted maybe 10 days this winter where the Powerwall was flat before off-peak kicked in, and we're not talking by hours. We only need solar to top up the Powerwall by a few kWh to allow us to be a little more profligate,
such as doing a laundry load or two.
So a larger battery is not always better. Pick something which fits your current usage, and add a wee bit of headroom. My plan is to stick with what I have at least until it has paid for itself (about 6 years to go - not bad, considering it was installed Oct '21).
Well i kind of getting thatLarger is certainly better if you want to improve your chances of staying off grid at peak-rate, but the law of diminishing returns applies.
I did consider having a second Powerwall (not possible anyway thanks to DNO edict) but the economics don't add up for our current usage. The ROI would be pushed out way beyond the warranty on the installation. This will change if/when we ditch the 25 year-old gas boiler for a heat pump solution some time down the line. At that point a second (or third) Powerwall (or equivalent) will make much more sense financially, DNO permitting of course.
Right now our house usage idles at around 360 Wh per hour overnight, rising to around 500 Wh per hour during the day. A single Powerwall is quite capable of handling that during the 20 hours of peak rate, with some left over for cooking. On poor solar days, immersion heater and dishwasher run overnight. So even in the darkest days of winter we rarely use peak rate grid - I counted maybe 10 days this winter where the Powerwall was flat before off-peak kicked in, and we're not talking by hours. We only need solar to top up the Powerwall by a few kWh to allow us to be a little more profligate,
such as doing a laundry load or two.
So a larger battery is not always better. Pick something which fits your current usage, and add a wee bit of headroom. My plan is to stick with what I have at least until it has paid for itself (about 6 years to go - not bad, considering it was installed Oct '21).
During quiet time during peak rate our usage is under 200 w.. unless wife decides that washing clothes is a must like NOW, so you can have washing and drying running at the same time . Si then suddenly it is 2000w or som + kettle and so on
I can easily have 14 kwh during peak rate darling winter (excluding any ev charging)
Now since 3 larger batteries are at the same price as 4 smaller (difference is 60 gbp!!) Then it makes sense to get larger 3 bateries.
you have to factor in what is practical to cover though. Spikes when the kettle is on - just ignore them. They're on for a couple of minutes and the battery will reduce the impact further. You can often adjust other consumption with minor changes in behaviour too - eg heat pump dryer will be lower baseline wattage rather than on/off spikes allowing more to fit inside a regular solar/battery coverage.
phil4
Member
It's not just usage you'd want to factor... sure bigger is better, but if during winter you want to charge it over night, does it's size and charging rate mean you can do so in the 3/4/6 hours off peak? They should, but if you start adding too much, and you're bound by the inverter you may run into problems.
Eg. extreme example, you've a 3.6kW inverter, so that's the max battery charge rate, and you've 3 x 9.6 kW batteries... to fully charge you need ~9 hours.
It's extreme, and probably not a problem for most, but worth a quick check on charge/discharge rates and work out what 100% would take, and check it's in/around your Flux/Go/IO period.
Also, keep that rate in mind for usage. Baseload no issue, but if you draw >3.6 while cooking (oven/hob) etc, it won't all be coming from the battery. All worth thinking.
Eg. extreme example, you've a 3.6kW inverter, so that's the max battery charge rate, and you've 3 x 9.6 kW batteries... to fully charge you need ~9 hours.
It's extreme, and probably not a problem for most, but worth a quick check on charge/discharge rates and work out what 100% would take, and check it's in/around your Flux/Go/IO period.
Also, keep that rate in mind for usage. Baseload no issue, but if you draw >3.6 while cooking (oven/hob) etc, it won't all be coming from the battery. All worth thinking.
TheManofMead
Member
I have a SolarEdge system - Solar PV with Battery. Have had the system little over 4 years. Last week the inverter broke and is unrepairable, so SolarEdge have agreed to replace under (10 year) warranty.
Afew worrying issues surround this, first of which is why are their products failing so early into a 10 year warranty. Have I just been unlucky or could it be the case that mass warranty claims jeopardise the future of the company meaning it folds and I'm left with no warranty. In the 4 year period since the original Solar PV installation the installer company have gone into liquidation (my battery was installed more recently using a different company).
Aside from warranty issues, the daily cost to me until the inverter is replaced under warranty could be a fair amount considering I am now buying every Kw from Octopus at around 35p (except the 4 hours cheap rate).
Afew worrying issues surround this, first of which is why are their products failing so early into a 10 year warranty. Have I just been unlucky or could it be the case that mass warranty claims jeopardise the future of the company meaning it folds and I'm left with no warranty. In the 4 year period since the original Solar PV installation the installer company have gone into liquidation (my battery was installed more recently using a different company).
Aside from warranty issues, the daily cost to me until the inverter is replaced under warranty could be a fair amount considering I am now buying every Kw from Octopus at around 35p (except the 4 hours cheap rate).
we had a Sofar 10kw invertor fail, well its works as an invertor but the comminication has stopped with data port and to battery storage, this was only a year old, replacement is begin sent out as we speak.
But it is on 24hrs a day, so the hours soon rack up, not many devices are on 24hrs a day 365.
But it is on 24hrs a day, so the hours soon rack up, not many devices are on 24hrs a day 365.
WannabeOwner
Well-Known Member
Mine was an Uno Aurora, failed after half a dozen years (out of warranty). Google the fault code and every PV installer in the land has a page offering a "Replacement installation for £1,000" - the fault is common on that vintage, and thus everyone is trying to catch the fixing business.
I found a DIYer who had fixed his for a few £quid - the error code indicated that a relay had failed, was a common fault for that model / vintage ... I just need to find a soldering-iron wielding nerd and then I can find a new home for it.
I found a DIYer who had fixed his for a few £quid - the error code indicated that a relay had failed, was a common fault for that model / vintage ... I just need to find a soldering-iron wielding nerd and then I can find a new home for it.
I'd probably go on a 4x multiplier. eg 3.6kw inverter works nicely with a GE 9.5 battery, I'd want a 5kw inverter for a powerwall. Pretty much at the point where you need an inverter/battery as a single unit so if you expand you get another inverter along with it so you're not bound by inverter limits for charging off peak
I found dealing with Otovo faultless so far.
you request quotation - they book time slot for a call with you and run through the installation. you can align with them if you want different size system than they offer by default and they provide you the link with the quote.
You can have various configurations whatever you want - I had like 5-6 different options to compare.
they are very efficient in email comms as well.
they are MCS certified and work with MCS certified installers only.
the best for me is that no downpayments required.
phil4
Member
I hope the rest works out as well, but remember so far you've been dealing with the sales peeps, where they make things as slick and polished as they can. The hard bit is what follows. Hope it goes as well for you as it has so far.
