Just been quoted for a 3.2kW system with battery and inverter, £10,790 (all Seasons Energy). Recons it would save us £880 a year at today's electricity prices. Is this competitive?
I don't know if it's competitive but if the guarantee is any less than 15 years on all parts and labour then it's not a sound investment as the quoted saving you're making means it will take over 12 years for you to pay back your initial investment.
The panels and labour are guaranteed for 30 years, the battery and inverter for 10 years. The price cap is set to rise significantly in April so that annual saving will most likely increase. I've got another company coming next Wednesday so it'll be interesting to compare.
The idea is to size your battery that it will cover a days worth of electric use. If you use 8kW a day then get an 8kW battery and on sunny days your electric will be free! If you get a 3.2kW battery but could have generated 8kW you’re missing out on savings. Historically the cost of electricity doubles every 9 years so whatever you’re saving in year 1 will be double in year 9.
Mines been in 12 month, it’s a 4kw system, we’ve have generated 4000kw on that period and I reckon we’ve used just about everything we’ve generated, if you have a hot water cylinder id 100% advise getting à I-Boost installed, it’s produced all out water feom May - September this year thus making a huge saving on gas too. As for batteries, I’m still sat on fence a little with them, for me, unless your buying off peak electricity from a supplier at a reduced rate then a don’t see how you can fully charge them up in the winter months as you’ll probably use what you’ve generated (fridge, freezer, lights been on etc) and in the summer months you typically use less electricity anyhow as it’s light for 17 hours of the day so there’s not as much emphasis on having the battery fully charged
On days like today my inverter won’t kick in until at least 8.30ish and mine is bang south facing with a 40* inclination, come 3ish it’ll knock off, if I use let’s say 4 kw through the day and my system produces 4kw then I’ve got a zero balance essentially, that doesn’t put any surplus into the battery, I am aware that Octopus Energy have a scheme where you can buy electric at a cheaper through the night
Very true, I just assume that people aren’t going to be continually drawing power all day, particularly when the weather is better. If you can run your house for free March to September it’s still a massive saving.
Yes, he said that some companies offer a reduced night rate but currently our supplier (Shell Energy) doesn't. He said they all will offer it eventually.
If you own them then I should think it would at the very least be a selling point. I suspect it would add some value...
That looks reasonably cheap based on current pricing, but it all depends on the size of battery and type of inverter being quoted for. 3.2kWh panel capacity seems quite small, as they'll typically try to put more than the 3.68kWh basic DNO limit (simplified approval process), allowing for some inefficiencies, but that's presumably a quote based on your specific roof dimensions, which are ultimately the limiting factor. I've just gone through a quotation process with numerous companies, but the choice boiled down to which was the best configuration for our requirements relative to cost. Cheaper isn't necessarily better. The main thing to check for is that the supplier is MCS certified and has HIES or RECC certification too. The efficiency saving figures that are calculated are very formulaic, and have to follow certain guidelines, but are simply based on how much your energy usage will be predicted to fall from having solar panels in place (i.e. it might calculate that you'll be 55% self-sufficient) but this doesn't take into account factors such as cheap electricity tariffs, etc. It's simply a calculation based on reduced usage at a fixed tariff. The most efficient payback available comes from utilising as much of the energy you generate, rather than any plans to export it back to the grid, as the old Feed-In-Tariffs are no longer available, so the payback on export is much less generous now. In summer, you'll produce much more energy than you can use, but in winter months you won't generate enough to cover daily needs, in all likelihood, so getting on an overnight tariff and charging the battery with cheap electricity for use through the day is a big part of the overall savings picture. Beyond this, there's the potential to use so-called agile tariffs where rates change every 30 minutes, to optimise the timing of import and export, but that's a level of complexity that most people won't want to consider. We have the complications of tree shading to consider, which makes optimisers a sensible option for us (additional cost, but improved levels of generation), and the battery system we've gone for is essentially plug and play expandable from the initial 10kWh being installed, but I'll wait to see what our real-life data looks like over the 1st year before looking at any tweaks to the system. We had a car charger installed last week as the first piece of the jigsaw (plug in hybrid car gets charged on the cheap overnight tariff and can be charged from excess solar generation when the panels are in place). We're also now using washing machine, dishwasher, tumble dryers overnight too when the cheap rate is in place (Octopus Go tariff - I can provide a referral code where each of us get £50 credit, if of interest). When the solar panels are in place, it will make sense to switch this back to daytime use in the higher-generating months. A hot-water heater is another logical option for excess generation, but we had our tank removed a few years ago via a combi-boiler installation so that's not an immediate option for us. Our system is booked for installation in mid-December. The best advice I can offer is to do as much research as you can to work out your usage profile (e.g. are you planning on having a car to charge, etc). Having done this, the conclusion that I reached was that if I had the choice of solar panels or a battery-only system, I would have prioritised the battery system based on having at least one vehicle to charge. Having both makes sense, but the savings calculation from the formulaic quotations don't take any of this into account.
Thanks for that mate, the company is All Seasons (based in Sheffield) and they have MCS, HIES and RECC accreditation. We've got another company coming next wednesday and another one who is giving me a quote without a visit but simply by using google earth images of the house .....
Quite a few of them do that. Ultimately, they'll still do a survey if you go ahead with them, having been quoted that way. This is a very simplified analysis, as technology is improving all the time on this, but shading is the real efficiency killer to be aware of, due to the way that the panels work. Depending on where the shadow falls, the efficiency drops on a standard full-cell panel are in 1/3 'chunks' and on a basic 'string' inverter system, each string will only operate at the capacity of the least efficient panel. A shadow on one panel could theoretically stop the entire string from generating anything, as a worst-case scenario. This is a good basic explainer on this. Most panels being sold currently are 'half-cell' which improve on these results, but it's good to understand any possible shading issues you have, and I'd expect anyone providing quotes to you to ask about them.
Thanks, we have no shading issues, no buildings to the south within half a mile (that might change in a few years time but the nearest buildings will be low-rise and about 50 yards away if planning is accepted) the nearest trees are at least 30 yards away and are quite small.
