Solar quotes which one to choose?

[mandc]

Hi all

Im thinking of having a solar pv system installed on my garage roof (suffolk pan tiles) ive had 4 quotes that are close so wondered if anyone here could help me choose.

1st quote *HIB* Longi HiMo5 405W All Black Mono solar panel x7
Growatt MIC 3000 TL-X 1ph inverter
rails ,fixings and labour total £4447

2nd quote
Canadian Solar 405w solar panel x 7
Solis 2500 Mini 5G with DC inverter total £5100


3rd quote *HIB* Longi HiMo5 405W All Black Mono solar panel x7
Sofar HYD 3000 hybrid inverter
total £4447

4th quote
Canadian Solar 405w solar panel x7
solis 2500 Dual 5G with DC inverter total £5700

Ive decided not to go with a battery (quote 3 has left the hybrid inverter in even though ive decided not to have a battery)
Quotes 1, 2 and 3 The panels are on one single string of 7
Quote 4 2 strings (block of 3 and 4 )
roof has no shading
the panels are in one straight line

hope this is clear enough thanks

 

[binky]

Sofar customer service is shite!

Make it a 3kw Solis inverter and that would be my choice.

 

[mandc]

hi thanks binky
would that be with quote 3

 

[johnb2713]

Ive decided not to go with a battery (quote 3 has left the hybrid inverter in even though ive decided not to have a battery)

IMHO it's a huge mistake not going for a battery, you would get the battery 0% VAT if it's installed at the same time as the rest of the Solar PV, a battery makes bigger savings in many ways that the Solar PV does. I personally would also have a bigger inverter with the battery so that it could handle greater loads without importing from the grid.

 

[binky]

hi thanks binky
would that be with quote 3

I doubt that contractor would change, they tend to quote for what their wholesalers can supply.

Your total wattage is 2.8kw, add a tolerance on the panels of upto +5%, and that is just shy of 3kw, which is why I would prefer to see the larger inverter. Undersizing is a little old hat and relates back to the less efficient inverters we used to fit. A 2.5 will work fine, but there's nothing more irritating than the inverter choking the power output on really good output days.

 

[mandc]

IMHO it's a huge mistake not going for a battery, you would get the battery 0% VAT if it's installed at the same time as the rest of the Solar PV, a battery makes bigger savings in many ways that the Solar PV does. I personally would also have a bigger inverter with the battery so that it could handle greater loads without importing from the grid.

thanks john but the quote with battery was 10k and thats way out of my budget

 

[mandc]

I doubt that contractor would change, they tend to quote for what their wholesalers can supply.

Your total wattage is 2.8kw, add a tolerance on the panels of upto +5%, and that is just shy of 3kw, which is why I would prefer to see the larger inverter. Undersizing is a little old hat and relates back to the less efficient inverters we used to fit. A 2.5 will work fine, but there's nothing more irritating than the inverter choking the power output on really good output days.

Thats a good point about chocking , something i had not thought about , do you have any preferences on the different make of the panels

 

[binky]

The 2 quoted for have the same efficiency and more or less the same spec, so no difference really. I've not fitted Longi, but have fitted a lot of Canadian Solar, which have proven to be reliable to date. Both are half cell, which is good. What I look for is low light output figures, which the Longi datasheet doesn't show. Low light performance is important for winter and gloomy days, everything flies along in bright sunshine, but mid winter is when you really want that bit extra from the system. Panel degradation over time is identical, so just based on lack of info from Longi, I would opt for Canadian, but I suspect there's naff all difference in reality.

 

[johnb2713]

thanks john but the quote with battery was 10k and thats way out of my budget

When I went down this route last year, I too couldnt afford a system at all. Looking at the figures and the difference it would make it really was a no brainer and I took out a loan to pay for it. The system savings more than covers the loan cost, wintertime is almost forget solar it does next to nothing but the batteries being there carried the house through.
Good luck with your system.
J

 

[Andy1733]

My advise would be future proof your system as best your budget will allow. I'm using the Solis 3.6k hybrid inverter which when installed around may. Brilliant output whilst the sun was shining. Get to November and the output dropped to about 10% of my usage. I now have just under 10kwh of battery's that are charge on a cheap over night tariff and I have had several days where these last all day and night...
From April to Oct the 7 panels would easily supply a 3.6kwh inverter..

 

[johnb2713]

My advise would be future proof your system as best your budget will allow. I'm using the Solis 3.6k hybrid inverter which when installed around may. Brilliant output whilst the sun was shining. Get to November and the output dropped to about 10% of my usage. I now have just under 10kwh of battery's that are charge on a cheap over night tariff and I have had several days where these last all day and night...
From April to Oct the 7 panels would easily supply a 3.6kwh inverter..

And how well does it support your peak energy consumption, the times when you're doing the Sunday roast / washing / etc etc?

 

[Andy1733]

For myself very good. Most dinners are cooked either slow cooker or air fryer and the way we dine it's usually still daylight so combo of solar and batterys.
Washing and dish washer run on the cheap overnight tariff.

The days we struggle would be on a Sunday if it's a miserable day. The batterys take up some of the slack but we draw from the grid for the rest. Though if you consider there's about 700 hours per month and we're prob talking about 10 hours per month it's like I say a very good fit for us.
One thing I may consider is a additional battery next winter. Though if I work out cost over savings it may not be worth it. I need more figures to get to a conclusion

 

[johnb2713]

For myself very good. Most dinners are cooked either slow cooker or air fryer and the way we dine it's usually still daylight so combo of solar and batterys.
Washing and dish washer run on the cheap overnight tariff.

The days we struggle would be on a Sunday if it's a miserable day. The batterys take up some of the slack but we draw from the grid for the rest. Though if you consider there's about 700 hours per month and we're prob talking about 10 hours per month it's like I say a very good fit for us.
One thing I may consider is a additional battery next winter. Though if I work out cost over savings it may not be worth it. I need more figures to get to a conclusion

I struggled with inverter capacity and battery capacity until I added my second inverter and additional storage. I used to get really annoyed seeing grid import even though I had 7kWh in the battery. Now my Import is less than 1 kWh per day every day, the batteries and solar keep the house going fine.

 

[Mark Time]

Isn't the trick of avoiding import to reduce or eliminate the use of high-load devices? The oven is the killer of course, which you can sidestep to some extent using a slow cooker etc. I swapped my kettle and toaster for low-power ones, no real hardship, it just adds a minute. I also have a low-rate immersion heater available for those super sunny days when the battery is already full ... although now I am moving to Octopus Agile maybe it is better to export any surplus?

 

[Andy1733]

Yeah Mark. It's always better to avoid importing but at what cost? I get from the post The OP is on a tight budget and listed prices between the option 3 inverter and a 3.6kw Solis for example is a couple hundred pounds more. Imo unless you go the full Monty and throw loads of cash at going off grid you have to balance the cost over reward. For me it's about savings in my bank not saving the planet. I did solar for financial gain. If I decide to spend another £1800 on a 4.8kwh battery I need to know I will I meet the break even mark around year 10. I'm speaking from a DIY install so I don't get any payback from the grid.
The down side to battery's are. In the warmer months my inverter produces way more than my 9.6kwh batterys can store. So if I buy another 4.8kwh batterys will it be sat full and not discharging for 6 month of the year?

 

[Mark Time]

Sure it depends on circumstances. At the moment battery quotes look awfully expensive. Looking around for an extra 3.3kwh LPH battery for my system and the internet prices are £1.5-2K, on a DIY install basis. If you are able to find what for you is an affordable battery I don't think you would regret it - if not know, the hybrid inverter gives you the future option.

 

[johnb2713]

Yeah Mark. It's always better to avoid importing but at what cost? I get from the post The OP is on a tight budget and listed prices between the option 3 inverter and a 3.6kw Solis for example is a couple hundred pounds more. Imo unless you go the full Monty and throw loads of cash at going off grid you have to balance the cost over reward. For me it's about savings in my bank not saving the planet. I did solar for financial gain. If I decide to spend another £1800 on a 4.8kwh battery I need to know I will I meet the break even mark around year 10.

The payback for me is a LOT less than that, just a tad over 4 years

I'm speaking from a DIY install so I don't get any payback from the grid.

I had my solar and battery pro installed to get the MCS for export but always aim not to export if I can. The second battery and inverter was all DIY and a payback of just over 2 years.

The down side to battery's are. In the warmer months my inverter produces way more than my 9.6kwh batterys can store. So if I buy another 4.8kwh batterys will it be sat full and not discharging for 6 month of the year?

The batteries are unlikely to sit full for 6 months, they would do some discharge every night, and unless youre in a micro climate with wall to wall sunshine every day, there will be a good few days with reduced output. I assume you already do energy divert to immersion etc?

 

[mandc]

hi all thanks for your inputs , you mention above that the sofar customer service is not great and would choose a solis inverter over sofar , does anyone rate growartt inverters . sorry for such a basic question but im really new to solar !!

thanks again

 

[johnb2713]

hi all thanks for your inputs , you mention above that the sofar customer service is not great and would choose a solis inverter over sofar , does anyone rate growartt inverters . sorry for such a basic question but im really new to solar !!

thanks again

Growatt had a bad reputation on their earlier inverters, the later ones are much better. I have an SPH6000 and it has been absolutely fine. The only thing to look out for with the SPH series is that the maximum power out when running on batteries is 3kW, even on a 6kW rated inverter.

 

[mandc]

Thanks john for the info on the inverter. ive had these quotes (above) but have also thought about installing the panels myself and getting an electrician to wire the system up im not to worried about selling back to the grid so dont need all the paper work for that , im a plumbing and heating engineer of 35 years so the main install would be no problem , but every electrician i speak to is not interested in the wireing up of the system , ive done a material quote and the 7 panels with inverter and fixing stuff would work out about 2k i was hoping a sparks could wire it up for 500 to 800 so would make a good saving. Can you see any problems with a DiY system ie house insurance ( although the install would be on my detached garage) and do you know any good sparkies in suffolk!!