MechanicalBuilder

Yes it’s national grid but they have only quoted to install single phase to the property as that what I requested at the time. The chap has been pretty helpful, I can ask him what transformer they intend on installing if it’s really worth me having 3 phase to export on. If the information the solar company is providing is correct and I can expect to see the circa £3000 a year return for exporting then it will be worth the investing. i just don’t believe it!

Thanks John, Yes it is overkill but when I’m getting it pretty much for free I don’t mind it. The point of having 2 smaller units is that they won’t be working nearly as hard as a single 12kw heat pump plus of air conditioning in my bedrooms in the summer time 👍🏻 the bungalow isn’t quite as small as a summer house! the crux of the story convo is whether or not I’m ever going to see the money they want me to invest in mains and solar again? The ideal is to self install and stay off the grid but I still have to fork out £30k to have mains even if I don’t use it 😞

Ive just created a very long post in the pv forum! thanks guys

Good Morning everybody, I found this forum whilst researching power options for our self build dormer bungalow. Originally our intention was to be partially off grid and self-install solar as we have previously self installed a 10kw off-grid system powering a workshop and static caravan for my parents. This recently took a turn for the worse when the surveyor discovered we were going off-grid causing the lender after 6 months of knowing about being off-grid, deciding they would not mortgage our property without mains electricity. This is coming at a massive cost of £32000 due to the location of the property. I was going to try and blag that we will have mains installed later but its looking like the surveyor is going to ask for certification or the MPAN number (possibly?????) Its a shame as we could have saved a fortune self-installing our own system. Anyway, the mortgage is now on its way and with the slab being poured this week, progress is being made! We have pretty much everything in place now with just one bug hurdle to make decisions on. The power. The bungalow is being heated via 2 ashp. One 8kw ashp for the 300litre hot water tank and UFH with a smaller 5kw utilising 3x air to air units in the bedrooms. I'm fortunate that my best mate is a heat pump engineer so his boss has really done me a great deal sourcing and installing my system. He has advised that a worse case scenario the combined consumption will be 7500 kWh per annum. Going off of this figure and what we consume in our current property I can only estimate we would possibly be looking at consuming 10000kWh per annum. With the solar...... The roof is south facing with a 40' pitch and no obstruction whatsoever. So we have had a few quotes now and the best of the bunch has proposed 2 options (this is subject to DNO) 1. 10k array, 8kw inverter and 19.4kwh battery storage. £20,000. 2. This option being the 'best case scenario' we could possibly fit on our property 28kw array, 8kw inverter and 38.8 battery storage. £31,500. Now, as you can see this has now gone from a cost of £10,000 ish if we self installed to a whopping 50-60k. I'm really in 2 minds what is best to do considering the DNO cap, export prices and what financially i will gain back over our lifetimes. --Is the extra cost of going as large as possible really worth it with export prices? we would essentially never draw from the grid and only export but does the 4kw dno cap throttle this? --As the mains isnt in yet we do have the option of going 3 phase thus increasing the amount we could export - at a cost obviously. At the moment the DNO is paying for the transformer upgrade but i think we may have to contribute if we want 3 phase. The only have to provide a suitable connection for free. --Do we go with the optimal sized system and export a little back to the grid and offset our electricity payments which at todays prices are going to be 250ish a month. --Do we have mains bought in but not use it, self install and stay off grid? This probably all boils down to whether we are ever going to see this 30-60k outlay for mains and solar back. Thanks in advance and sorry if I have left anything out, we are 5 days overdue with our second child, we have a 3 year old and i'm trying to manage this build. I CANT WAIT TO SLEEP AT NIGHT AGAIN hahaha Phil Mechanic turned builder!

Good Morning all, Currently self building our forever home in Somerset. I Found this forum via google after researching advise and found some of the contributing posts very helpful indeed. We did intend on going completely off-grid but unfortunately our mortgage lender put a stop to this!