Solar Panel help please

woolgar.c

We've recently started looking in to solar panel systems & getting quotes. The more we've looked in to it the more confused we feel. 
Can anyone offer any advice or a service / person we can speak with for some impartial advice. 

Our aims were
- to offset our energy bills so they are reduced as much as possible (& the money that would have gone to energy bills will instead go to paying off the solar system we get installed). 
- a simple system that can hopefully automate charge & discharge from the grid at optimum times

We have a fully south facing roof, a slightly south west facing roof and a south facing garage roof. No shade across any of it. The house roofs can fit approx 10 or 11 panels, if we include the garage we could fit about 14.
I work from home 5 days per week, toddler is also home 1 day in week, all 3 of us home weekends. We have a hot tub too. 3 bed house end terrace to give an idea of size. 

We're struggling to figure out what system combination is best to reduce our bills without spending more than needed on the system itself. It's also hard to figure out how much real difference there would be between things like type & quality of panels, inverters, batteries. 

we've looked in to & had quotes for panels ranging from 430 to 455W, batteries from 5 to 13.5Kw, inverters & microinverters. 

Also unsure if a DNO application would be worth it. 

We've watched endless videos from Gary does Solar & tried various combinations in his online solar modelling calculator but we've ended even more confused. 

Please help!

Reed_Richards

You have no choice, you have to make a DNO application (or your installer will do that on your behalf).  But if the maximum export from your system is limited to 3.68 kW then it's almost automatic that your application will be approved.  If you want to export more than 3.68 kW, approval will depend on local conditions, such as the capacity of the wires that supply your house.

There is no "one size fits all" for solar panel and/or battery capacity.  You have a hot tub and they can consume large amounts of electricity, working out a combination of solar power, battery power and cheap rate electricity that you could use to minimise the cost of running the hot tub might be a useful guide. 

woolgar.c

Thanks. I was thinking of the application to export more than 3.68 kW, good to know it's dependent on local conditions. I'll try to find out if that's likely to be approved for us. We had thought it may be worth doing as seems to improve our calculated figures but I'm unsure if it's worth it. 

Your guide is exactly what we're trying to work out & where we're getting stuck. We can't seem to actually figure out what system size is best. Some of our quotes were 11 panels and as we learnt more we thought the largest possible array is probably best so 14 panels would be better (by including the garage roof). 

The battery seems to be the more significant cost. I'm unsure how much we would benefit from adding one, or perhaps just opting for a small one. My husband is more keen & likes the idea of a larger one, utilising Octopus Flux and forced charge / discharge at key times. We may get an electric or hybrid car in the next 3 or 4 years.

I feel like we need to get back in contact with some companies to amend our quotes in terms of panel size but as a guide this is what we have so far. Any input on quality & things to consider would be great. So far it seems each company has good reviews, I think the equipment is more variable.

Our average daily consumption is 23 kWh. If it helps additionally to the info in my first post the roof pitch is 40 degrees. 

1. Greenscape
(this was via a scheme currently running in Kent which in theory should make it cheaper but also seems to have the worst equipment of the quotes)
11 x 430W Longi LR5 panels (system size 4.73kW), Fox ESS H1 Series Inverter, Fox ESS EP5 5 kWh battery. Includes optimizers, bird guarding, scaffolding to the 2 roofs. Someone has been to the house to check pitch of roof etc. £8,895

2. Nano Protech
11 x 455W Aiko panels (system size 5.05kW), Tesla Powerwall 3 13.5kWh battery (I believe this is also the inverter). Includes scaffolding to 2 roofs, DNO application (not sure if this is for the 3.6 limit or beyond), gateway. £13,752

3. Soly
They suggested 13 panels on the 2 house roofs but everyone else has suggested 10 to 11 would fit.
13 x 455 Aiko panels (system size 5.92kW), Giv Energy battery 13.5 kWh, Enphase microinverters. Includes scaffolding to the 2 roofs.  £12,594
 
4. Bliss
They suggested it would be easy enough to add another 5kWh battery. The below price is discounted. They suggested the microinverter they use is one spec up from the one in the Soly quote.
14 x 455 Aiko panels (system size 6.37kW), Enphase battery 5kWh, Enphase microinverters. Includes scaffolding to the 3 roofs. someone has been to the house to speak with us but didn't measure the roof or pitch. £12,675
(same quote but for 10 panels on 2 roofs with no discount was £11,541)

5. Cahill
I think this is the point at which my husband has been trying to figure out the different battery options. We have 3 quotes from Cahill for the same panel set up but with different batteries & hence different inverters. 
10 x 440 DMEGC panels (system size 4.4 kW). 
a) with Fox ESS EP5 (5.1kW) battery and Fox ESS H1 Series inverter
b) with Tesla Powerwall 3 (13.5kW)
c) with Giv Energy All in One (13.5kW) battery and Fox ESS F Series inverter

Reed_Richards

Do you have a smart meter?  You are going to need one if you want to be paid for exporting electricity and if you want to charge your EV/Plug-in Hybrid at cheap overnight rates.  If you don't have one then get that organised now as there is often a bit of a wait required.

How much electricity do you use in a year?  You will tend to use more per day in winter but is that a lot more or a little more?  You might want to match your battery capacity to your daily use so you can charge it at a cheap night rate then use it to power your house during the day.  I don't think you are aiming for more than 5 KW peak output from your panels, which is decent but not huge.  

I can't really advise about battery options, except that a Tesla Powerwall is fancy but one of the most expensive in terms of £ per kWh of capacity.

And if you post your query to the Green & Ethical board https://forums.moneysavingexpert.com/categories/green-ethical-moneysaving you will get far more people advising than just me. 

Screwdriva

In my view, all of the above quotes are poor value. That said, in my view, the Tesla PW3 is the best battery on the market, bar none. The fact that it will soon be integrated with Octopus intelligent tariffs is the cherry on the cake. 

A Kent based installer I have used for multiple installations have quoted 13 X Sharp 435W bifacial panels + Tesla PW3 + Gateway 2 fully installed for £11.7K. That's a £2K savings over quote #2 with arguably superior panels. G99 + bird netting included. 

I'm confident you can do far better than the above quotes! Best of luck! 

woolgar.c

Reed_Richards said:

Do you have a smart meter?  You are going to need one if you want to be paid for exporting electricity and if you want to charge your EV/Plug-in Hybrid at cheap overnight rates.  If you don't have one then get that organised now as there is often a bit of a wait required.

How much electricity do you use in a year?  You will tend to use more per day in winter but is that a lot more or a little more?  You might want to match your battery capacity to your daily use so you can charge it at a cheap night rate then use it to power your house during the day.  I don't think you are aiming for more than 5 KW peak output from your panels, which is decent but not huge.  

I can't really advise about battery options, except that a Tesla Powerwall is fancy but one of the most expensive in terms of £ per kWh of capacity.

And if you post your query to the Green & Ethical board https://forums.moneysavingexpert.com/categories/green-ethical-moneysaving you will get far more people advising than just me. 

Thanks, I'll add a post in that forum too. 

Yes we have a smart meter & currently are with Octopus, although we'd want to switch to the Flux tariff once the solar system is installed. 

I think we actually use less energy in winter when the hot tub isn't out. Last year our average monthly summer use (without hot tub) was about 270kWh, this year (with hot tub) it's about 855kWh. Last winter average monthly use was about 495kWh. Average annual use was 532kWh

vic_sf49

Have you considered getting Octopus out to quote for fitting them? Other energy companies may still fit them, as well.

Octopus installations have been mentioned a fair bit on these boards, and the other company I'm trying to remember, may have been EDF*. 

*It was one of the "E" names, so EDF or Eon.

Can't comment on the specs, prices, or quality, as I haven't used them for a solar install.

Reed_Richards

Eon and/or Eon Next offer huge export payments for systems they have installed.  I'm not sure how long these payments last.

woolgar.c

Thanks. No I hadn't looked in to a quote from Octopus but I will do that

cash-magnet

My own solar install is very small compared to the average house but I concentrated on reducing my electricity usage before sizing my solar setup rather than getting a huge pv installation which isn't cheap.. Personally I do not export any electricity to the grid. It is all stored in my battery bank and gets used as and when it is required by myself. I sized my battery to hold 3 days of electricity which is used during my peak-rate period and any topping up in winter is done using an off-peak tariff.

The panels are the easy part, but a well sized battery and good capacity inverters are where I would be concentrating on for a happy solar experience.

woolgar.c

cash-magnet said:

My own solar install is very small compared to the average house but I concentrated on reducing my electricity usage before sizing my solar setup rather than getting a huge pv installation which isn't cheap.. Personally I do not export any electricity to the grid. It is all stored in my battery bank and gets used as and when it is required by myself. I sized my battery to hold 3 days of electricity which is used during my peak-rate period and any topping up in winter is done using an off-peak tariff.

The panels are the easy part, but a well sized battery and good capacity inverters are where I would be concentrating on for a happy solar experience.

Thank you. Good to hear your experience & the benefit you are getting just from the battery without any export. 

We have run some calculations now on our average daily usage, base load, expected array size and utilising the best forced charge / discharge timings to make the most of the flexible tariff. We've concluded that we need a battery of at least 10kWh. Still figuring out if the Powerwall is worth the extra over other battery models.