Solar - what do I need to know?

Screwdriva

EssexHebridean said:

Thanks all - interesting on the battery side of things. We’re very much getting two sides on his - people are either very pro battery, or are on the other side of the scale saying it won’t be worth it. Potentially, if this works for us, in the longer term we would look at possibly reverting back to E7 in order to have the ability to charge the battery overnight at times when the solar is performing well  - although that clearly depends on availability E7 tariffs going forwards - if not though I suspect there will be other TOU tariffs that could have the same effect. Definitely one for us to think about more fully though as obviously the battery costs are a big  part of the quotes. 

On the water tank, the house doesn’t have one - we’ve a combi boiler and are absolutely loving the ability to have economically heated hot water when we want it and not be paying to heat more of it than we need. (Coming from 20 years of dealing with an immersion heater this is a definite luxury!) Realistically our only options for a cylinder here would be to either lose a big chunk of space from our spare room to have it installed there (not ideal) or to have it up in the loft - which is definitely not happening as we don’t want water up there at all - so this wouldn’t be something we’d consider really.

On the battery, as a general rule of thumb, if you consume more than ~4000 kWh per year, a battery slowly starts to make financial sense. Heat pump owners and EV owners who drive alot almost always fall into this bucket. 

On hot water, you have another option which is a heat pump built into the hot water cylinder. The MixEnergy iHP has been very well received since its debut last year. When paired with the right ducting and time of use tariffs, it can minimize hot water costs beyond any boiler's capability. It's on my shopping list!

On the panels, I'd place JA Solar in the same bucket as Jinko or Trina, as shared above. They are all available for £30 a panel wholesale to installers. No quality whatsoever. 

Slinky

Qyburn said:

Slinky said:

We have a hot water cylinder and considered having a diverter, but it was going to cost £500 to supply and install, and £500 buys an awful lot of gas at under 5p/kwh on Octopus. I'd rather get 15p/kwh exporting excess after the battery is charged. 

Same here. Although we don't have gas, oil is still much less that 15p/kWh so wouldn't be worth heating water instead of exporting.

To be fair none of the installers we spoke to recommended a diverter. It would be different if you were only getting 3p for export, and even more so on deemed export.

We first spoke to potential installers about 4 years ago and they were mentioned then. When we started speaking to them again last year, none of them mentioned it until asked. It seems like diverters have fallen out of fashion.

paul991

diverters are great if  you want to maximise self consumption ,I get a deemed export payment and although could make more money on a export tariff I like to have the  hot water and a little space heating most  days .My   P v has  paid for itself so will keep using the diverter until I get a battery or heat pump etc  

EssexHebridean

I think we’re about ready to go with this. We have had two additional quotes - and those two suppliers each think that they can get either 8 or 10 panels on our roof. However, for various reasons we’re not quite as comfortable with either of those suppliers as we are with the first one who quoted. That original supplier have now re-quoted favourably based on 8 panels, and we think we’re going to go with them.

We really are a bit in two minds about the battery - MrEH feels strongly that he’s not keen on going ahead without the battery as well, I’m a bit more ambivalent but allowing that we are already well versed in load-shifting after 20 years of E7, we do both feel that it will be relatively simple to get back into that mindset again and that could well mean we can maximise the advantages of a battery once we’re got to grips with it. We’re going to continue to mull the whole thing over during the weekend and will make a final decision early next week I think. 

Anyone got any views on Octopus Flux as a tariff?

Reed_Richards

Sign-up with Octopus and you can currently get 15p per kWh for your exported electricity.  But every kWh you import you pay at least 10p more (I've lost track of the exact price).  And on Economy 7 or similar you can charge you battery cheaply every night.  I heat with electricity so I use a lot of it and I think that strengthens the case for having a battery.  I got my battery almost 4 years ago and I'm not sure if I'll ever recoup the cost but I do enjoy running electrical appliances like a washing machine and not having to curse if the sun goes behind a cloud when it's heating the water.     

cm4ever

EssexHebridean said:

Anyone got any views on Octopus Flux as a tariff?

Without knowing any specifics about your potential total usable battery capacity and typical daily house total load - if your storage can be fully recharged in the 3hr Flux cheap night window and can power your house until the next morning - that's near enough the only main import unit cost for your electric you'll actually care about.

On the other hand, if your storage can at least cover the house load until after the peak evening period, again you effective import cost with be a percentage mix between cheap and middle tariff unit costs.

I suspect you'll already of figured that out, but it's worth spelling it out.

Getting battery storage isn't necessarily right or wrong it depends on your point of view.

I've been on Flux since it came out - bought my system before it was available and I've been really happy on it - even throughout the winter as my system covers my daily total house load i.e. generally only pay the cheap unit cost for all imports.

Flux has also been good for generation and meant my energy bills have dramatically reduced due to the generation income during the summer.

In fact I'd switched to variable direct debit in April and haven't paid any more money to Octopus yet - I expect to be short by about £8/9 this January dual fuel bill - I'd had a credit balance of £200 in April. The Octopus saving sessions also helped boost our slowly dwindling credit balance this winter.

Word of caution / something to think about - IO Flux is available as well now, but only to certain storage at the moment and has dramatically different unit import/export pricing structure....

zxzxzx

Agree with @cm4ever completely, got my solar/battery March last year and on Flux by mid April. It made me a buffer fund to see me through this winter with cash to spare. One thing I have done differently is to move to Agile around Christmas as no sun/no export so it made more sense to buy cheaper night time to charge my batteries BUT that won’t work for all.
I have found, as you are,  that the whole solar thing is a major learning curve.

Netexporter

The Gary Does Solar video series on Youtube is worth watching. He has also developed a calculator that includes the various Octopus TOU tariffs so you can compare your usage/solar and battery set-up on each tariff to see which works best for you circumstances. There's a free version of the calculator and an even more comprehensive one for subscribers.

EssexHebridean

Brilliant info - Thank you. This potentially also opens up questions around battery size - we have quotes for 5.2 and 9.5kWh batteries at the moment and had pretty much dismissed the larger but will look back over things again now. Our heating is gas within the house, but MrEH’s WFH office is a an outbuilding with electric UFH so in seriously cold weather that chews threw electricity fairly rapidly - being able to run at least the majority of his use from the battery would be tempting, plus we could potentially get a timer fitted to switch it on to heat during that cheap overnight period, after which it would use substantially less during the day… of course there would also be some odd shifting to that overnight period as well, which we would need to take into account. 

Much food for thought! Pretty sure further discussions will lead to further questions…

one I have just thought of - can you choose during the day whether to take energy from the grid or from the battery? Or does it just go Solar > Battery > grid in terms of preference? Apologies if that’s a really silly question to those who have knowledge of this sort of thing! 

QrizB

EssexHebridean said:

Brilliant info - Thank you. This potentially also opens up questions around battery size - we have quotes for 5.2 and 9.5kWh batteries at the moment and had pretty much dismissed the larger but will look back over things again now.

I suspect you've been offered single-manufacturer battery systems, but I'm fond of the a la carte approach where you have a hybrid inverter and a stack of eg. Pylontech rack-mounted batteries. It makes future expansion of your battery a much simpler process.

A neighbour of mine recently had a Solis hybrid inverter fitted plus (I think) 3x US3000C batteries. I helped him set it up to make best use of his E7 over the winter (the installer hadn't bothered showing him). If experience means he'd benefit from more storage, it's simple enough to add another to the pile.