Solar Panels or PV's (Photo Voltaic)

   Solar + Batteries make the perfect combination. Best to get them installed as a pair. If I were only able to have 1 I'd go for batteries first.
   As you can see WHEN you charge your house battery \ EV can make a huge difference to your bill. Charging the house battery at night gives access to night time prices during the day. 1/4 the price !

   PV's can divert excess energy to either your hot water tank or your car and possibly both.
But speaking from experience-
  • Buying from the grid at night costs 7p/kWh but I can export solar during the day for 15p therefore its cheaper to charge at night and export as much solar as possible during the day
  • Charging a car battery 67kWh from a 10kWh battery very quickly kills your house battery. That leaves you at the mercy of high daytime prices.
  • My inverter deliver 5kW max so charging the car on the regular 7kW EV charger draws 5kW from the battery and 2 more expensive kWs from the grid. Some chargers have "Solar Charging" settings such as the Ohme or ZAPPI. 
Not sure how many panels you need ? Batteries ? Battery size ? Check out garydoessolar.com it has a awesome online modelling app.

House Battery

   Storing electricity in a house battery allows access to the cheapest energy throughout the day. That energy may come from-
  • Solar on your roof
  • Cheap night time rate
  • Excess renewable give away's such as Octoplus free electricity.
 Tesla Power Wall
   Here's my Solis inverter and house battery data for a cloudy winters day. As you can see little to no solar. Making the most of night time (23:30 - 05:30) cheap rate 7p/kWh electricity by charging the cars the house battery, heating, immersion heater & dishwasher.
   During the depths of winter the battery isn't sufficient to run the heating for long periods and frequently runs out at peak grid times (4:30 - 6:30pm) so I've programmed the house battery to top up 2:00 - 4:00pm so it can take us through the peak grid times. I could have had a larger battery to give cheap heat during the day but it's only a few days a year so not worth the additional expense.
The cost of PVs and house batteries have dropped significantly. Home made electricity is now much more affordable.
8 Panels might cost around £520
10kWh of battery costs around £2000
Plus installation

​Solar PV vs Thermal

PV's

Pros
  • Convert sunlight directly into electricity
  • Can charge an Electric Vehicle directly
  • Can charge a house battery directly
  • ​Can export to the grid and get paid
Cons
  • Only 19-25% efficient
  • Larger roof area required
  • Storing the energy can be expensive as you need something like a £7000 Tesla power wall.
  • Cant charge the car if you've gone to work in it

Solar Thermal

Pros
  • 80-95% efficient converting sun light to heat
  • does not require and expensive house batteries
  • Low installation costs
  • Can top up hot water tank with cheap rate night time electricity
  • ​Small roof area required
Cons
  • Requires hot water tank
  • Cant charge a power wall or car​