DIY Solar - what a buzz

[rider]

Most people will probably be oblivious to 2019 legislation that detailed rolling blackouts to protect the National Grid output at times of stress, introduced as the country is nearing 100% capacity. Different areas to have their power cut on different days. This legislation was topped off in 2023 with 'in event of an emergency' legislation detailing up to 7 day blackouts on domestic property and 'certain' industries.

Aside from rising utility costs we have seen increasing number of power cuts, from a few seconds (I have lost a very expensive printer to a rapid sequence of on/off spikes) to blackouts lasting for several hours so, I went full on engineering project and did a DIY solar build on 2 pretty large two axis trackers. It is operating off grid but I have retained options for house backup supply from the mains or our generator ready for those dark Winter days. 

The build started with painting the metalwork in March and ended this month with an electrician brought in to do the final fix on the inverter and house feed cable. On a nominal 8Kw the system has peaked power delivery at 6.8Kwh in the sunshine and still delivers around 1Kwh on rain soaked days. There is a 20Kw battery store which on sunny days is recharged by 10am and on cloudy days has managed to be fully charged by the days end. This is at peak Summer where sunshine hours are 5 times those in the deep Winter months. 

A year ago I knew nothing about Solar so anyone clued up can reasonably expect to be capable of putting together their own DIY setup. We now have our own off grid power and our own bore hole water both backed up by mains electricity and mains water at the moment. If anyone considers their own entirely DIY installs, it was intense but overall quite satisfying seeing the end result and output. 

 

[TuneR]

Awesome setup, they look like giant robotic trees. Add a bit of metal artwork to the edges and spray it yellow and you could have a giant sunflower or go full on steampunk ha.

 

OT is the main cost of the build the batteries? There looks to be a bit of cost in the mechanical bits too, the axis tracking machinery... Also is there any reason not to hook the batteries up to the grid and have them charge at night during winter days at cheap rate? Total noob here jic questions are daft.

[rider]

The trackers were not expensive, US$2,800 DDP for the pair. They came with some spare parts too which was an unexpected bonus; a motor and two spare controllers. The batteries are the big ticket item at over £6k but still, the entire build came in just shy of £17k which I've been told by friends who used to install solar equipment is a bargain final cost. I did put in a lot of hours though doing the shed build and stud work for all the electrics as well as time spent actually assembling the trackers and ducting or just running a lot of cabling underground.

The inverter is not tied to the mains as you then need to register the installation with the local electricity network provider (National Grid) who would then have an implied right of access to perform an on site inspection. 

I'm fortunate to have the space and all the digging and lifting equipment required to do the job without recourse to paid help or equipment hire. That was important throughout April and May as there were only a few days that were dry enough on the ground to be able to move heavy equipment in and out of the site area.

The site is not overlooked from the road or any neighbouring properties so it's placed to be as inconspicuous as possible to minimise the risk of theft of hardware and also possible complaints from anyone in or passing through the area. So, no one would get to appreciate it if it was decorated.

[Swampy442]

All seems a bit tinfoil hat to me, if that was your only reason to do it and, like you said you have the luxuries of money, equipment and space which many dont. 

Personally Id do what many others have and just get a Tesla battery and use it as a UPS, but chapeau for the work.

 

Edited August 4 by Swampy442 (see edit history)

[johnny g]

23 hours ago, Swampy442 said:

All seems a bit tinfoil hat to me, if that was your only reason to do it and, like you said you have the luxuries of money, equipment and space which many dont. 

Personally Id do what many others have and just get a Tesla battery and use it as a UPS, but chapeau for the work.

 

I actually toyed with getting a few Tesla batteries and then charging them up on an offpeak tarrif to see us through the day. But you're talking £20k plus for 3 batteries. Then it's just under 40kWh, at £0.07 per kWh. Call it £3 per night, rather than £10.50 or so on 
It's 8 years to pay for itself.
 

Wasn't worth it for me.

[rider]

There are a few recycling companies now selling certified EV batteries for repurpose use in domestic and commercial power storage applications. You can buy certified, 80%+ charge capacity, 80Kwh Tesla batteries for £10k. Well under half the price of new battery storage. I know from our production output that we are wasting, not using or storing, up to 40Kw a day of available energy on start to end sunny Summer days and extra battery capacity could have us sail through several consecutive cloudy days without any need to resort to a generator or mains top up. 

My setup is single OEM plug an play, I suspect wiring up a mix and match of inverters to batteries could bring you into some kind of BMS mine field to navigate.