Critique my system

[JonboyP]

Hello all,

I've got to get a move on with a solar PV setup for home, to eliminate or at least drastically reduce my bills come December when my fixed tariff runs out.

I'm not an electrician, but I do have the services of an electrician available for the connections and I shall be doing most of the installation work myself.

Our useage varies between 8-15kWh per day, a bit more when we run the hot tub. We don't have an EV but may do in the future. It's a detatched house, gas central heating and water but I plan to install an iBoost system to heat the water. I work shifts so some days I am home during the day and out at work at night, sometimes the other way around.

Our roof is a hip-ridge affair with a large east (will fit 6 modules at 1052 x 1776mm) and west aspect (5 modules) and a smaller (3 modules) south aspect. I also have a large garden shed with a pent roof facing south 6m x 3.6m with a clear unobstructed view until around 3-4pm during the summer.

My mat helping me has propsed a system but no battery. I've come up with the following based on my own research which I appreciate may not be up to scratch.

Modules https://www.tradesparky.com/solarsp...30-410mr-black-frame-half-cell-solar-pv-panel

Hybrid Inverter https://www.amazon.co.uk/Iconica-Inverter-controller-battery-charger/dp/B07CTS3JB6

or this one, which I think is just single MPPT: Hybrid Inverter 2 https://1va.co.uk/maxic5000-clearance-grade-5kva-4kw-48vdc-mttp-solar-inverter-p-33.html

or this one: Solis Inverter https://www.bimblesolar.com/solis-3.6kw-hybrid-inverter-48v

Battery https://voltaconsolar.com/batteries/lithium-ion/pylontech-us5000-lithium-

Although I think maybe it might be a good idea to try and get hybrid inverter and battery from the same manufactrer?

At the moment the proposal is 14 modules (6, 5 and 3) of the 1052 x 1776 flavour to go just on the main roof. I am not averse to putting stuff on the shed but my mate doesn't seem to think this will be necessary.

Please, be gentle with me when you give your advice!

Jon

 

[binky]

I would shop around on the panels, I can get those £40 cheaper - trade of course.

Solis is fine, it's G99/G100 certified, other 2 are not and will not be accepted by the DNO.

Pylon tech is fine.

Bit of a problem with south roof, most inverters have 2 MPPTs, so 2 inputs, you could do with a third as connecting south side to either east or west will make it difficult for the MPPTs to extract the maximum energy from the system. MPPTs work to a preprogrammed expected power curve, which will be offset more than most can cope with with 2 different facing arrays connected to a single input. Solaredge or micro inverters maybe the way to go, or just leave the south side out of the equation.

Are you sure shed roof is strong enough?

Have a read of other posts on here, most of the info is in there somewhere.

 

[JonboyP]

I have been lurking for a few weeks and reading what I can, it's just such a big investment and I can't afford to bugger it up!

Shed is fairly sturdy and brand new, built it myself. 100x50 joists at 600mm spacing, doubled up in the middle, with 9mm OSB sheathing and a felt roof. I'd be confident it could take a bit of weight. The shed CU is fed from the main CU by a 6mm or 10mm (can't remember which) SWA cable. I could not run another cable from the shed to the house, so I guess I'd need a second inverter going into the shed CU?

Maybe I could end up with a bit of a mixed system, with an array on the shed feeding a plain inverter, feeding the house, and the roof arrays feeding a MPPT/hybrid inverter/battery system, as well as the house CU? Oh blimey, what a thought! I have no idea if that's allowed/possible/sensible.

I hear what you're saying about the small south array. I could augment this with another two or three modules possibly on the south-facing section of my garage roof, which is lower than the house roof but still largely unshaded. I'd still need a 3rd MPPT 'input' though. It's a quandry.

 

[binky]

seperate inverter in shed, perhaps use AC battery charger to take charge from both arrays.

There used to be inverters with 3 inputs,b ut I havn't seen one for a while. SMA used to do that sort of thing.

 

[JonboyP]

Mounting systems.

Does it matter which brand of mounting system I buy?

Let's say I go with the JASolar modules above, what sort /brand brackets and rails would I need for a standard pitched and tiled roof?

 

[NozSpark]

I don't know much about solar,,, but if you are thinking about getting an EV I would seriously consider getting a myEnergi EDDI instead of the iBoost,,, it, and PV monitoring, tie in seamlessly with their Zappi 2 charge points

 

[binky]

Mounting systems.

Does it matter which brand of mounting system I buy?

Let's say I go with the JASolar modules above, what sort /brand brackets and rails would I need for a standard pitched and tiled roof?

Schletter is my frame of choice, but frames are universal, whatever the make of panels

 

[Bob Smith]

Hello

how far did you go with your design?

Here are, what I hope are useful links:

To check if your inverter is approved
https://www.ena-eng.org/gen-ttr/Index?Action=ViewDetail&EID=59082185&tab=search
To calculate the minimum and maximum number of panels per string
https://solardesignguide.com/calculating-string-size/
If you intend to maximize the use of the surface area by selecting different panels size, there will be additional checks
https://support.tigoenergy.com/hc/e...xt=You can mix and match,than or equal to 25%
Be aware that there could be additional calculations, which I am not yet aware of, to be performed for the above criteria to validate a design.


Also, I am told the inverter should be as close as possible to the modules. However, I have not been able to verify this information nor quantify it. I hate when people are not specific!

Hope this helps and keep us posted. Good luck

 

[deanwilts]

Also, I am told the inverter should be as close as possible to the modules. However, I have not been able to verify this information nor quantify it. I hate when people are not specific!

Electrical wire has an internal resistance, which means electricity gets lost (as heat) and the longer the wire the greater the loss. So the general rule of thumb will always be keep wires as short as possible to avoid losses/waste.

The higher the voltage in use, the lower the relative loss experienced, so for that reason if you have to run long wires from modules to inverters, you should increase the voltage on the strings. This can be done by creating strings made up of modules connected in series rather than in parallel. This is what I'm looking to do as I have a minimum of about 130m I need to run my cables (to back of a field).

 

[binky]

Electrical wire has an internal resistance, which means electricity gets lost (as heat) and the longer the wire the greater the loss. So the general rule of thumb will always be keep wires as short as possible to avoid losses/waste.

The higher the voltage in use, the lower the relative loss experienced, so for that reason if you have to run long wires from modules to inverters, you should increase the voltage on the strings. This can be done by creating strings made up of modules connected in series rather than in parallel. This is what I'm looking to do as I have a minimum of about 130m I need to run my cables (to back of a field).

I once worked out 4mm solar cable on 4kW array is good for about 100m cable run. The advice about keeping the DC short is more to do with safety of the DC side, but it has been used a lot to justify sticking inverters in attics, which is not a great location for these devices in summer. I've fitted a lot of inverters outside on external walls , with DC cables run externally in conduit. Most inverters are IP65 rated, which makes this possible. Most Consumer units or meter boxes are also on an external wall, which keeps the AC cabling short.

 

[johnb2713]

Most inverters are IP65 rated, which makes this possible.

I didn't realise most inverters were IP 65 or better, I still don't think I'd be happy leaving it exposed to the elements. My battery build along with inverter and BMS is going outside but in a very narrow and not very deep garden shed type building. I intend to have a small heater under the batteries and insulate them with Kingspan, just keep them above 16 deg C in winter and cooling fans for the warmer days. So hopefully my Victron inverter will be happy in it's little house outside.

 

[binky]

I didn't realise most inverters were IP 65 or better, I still don't think I'd be happy leaving it exposed to the elements. My battery build along with inverter and BMS is going outside but in a very narrow and not very deep garden shed type building. I intend to have a small heater under the batteries and insulate them with Kingspan, just keep them above 16 deg C in winter and cooling fans for the warmer days. So hopefully my Victron inverter will be happy in it's little house outside.

inverters are designed to go in gardens and other places like solar farms. Ideal location is a shaded outside wall, so it's not in the hot sun and gets plenty of air movement. My own inverter has been working fine outdoors for 11 years now. Most solar farms are also built this way after they found big central inverters are a pain in the neck, plus it cuts down the DC cable runs. Running SWA back to a hub is easier and safer than running DC cables, especially when buried as the DC cable fails after about 5 years when constantly wet.

Batteries are a differnt matter, they need a dry shelter and a little warmth in winter.

 

[johnb2713]

inverters are designed to go in gardens and other places like solar farms. Ideal location is a shaded outside wall, so it's not in the hot sun and gets plenty of air movement. My own inverter has been working fine outdoors for 11 years now.

Every day a school day, thanks your valuable advice, much appreciated.