To encourage home and business owners to look first towards investing in what is very simple and low cost in China, is a very complicated and over engineered high cost in the UK and USA.

As a solar water heating systems designer of 25 years, those not wanting BIG brand named products, which is why we have today a 4 person home system costing £4.500 installed (supplied by the STA)
It seems that unless there is a return on investment within a short time, useing the suns tax free energy is not an incentive to invest £4,500, which I also agree.
When I started to promote and sell my own SWH system kits, it was to use where possible the existing hot water tank, unless the tank needed to be replaced as was old and leaked heat through the insulation.
My simple Thermix valve, that was inserted into the top of the cylinder allowed the solar heated water into the bottom of the tank and hot water out of the top, with no worries like today of stagnation, freezeing and servicing all the pressurized parts of the unvented / closed loop system

Our planned new lower cost prices, based on me able to find an importer to import 80% of the parts from Israel and China will bring back my under £1,000 system kit cost.
The Hot Water Tank should never be included in ROI, as the boiler isnt, the rest of the appliances in the house are not, so why has the hot water tank.
The introduction or the Renewable Heat Incentive Scheme (RHI) in April 2014 opens up new oppotunties to offer the home owner a choice:

1. Except the current system of going through a green deal assesment to check your level of insulation is up to latest standard, before you can apply for a SWH system under RHI
2. Through the payment of £4,500 installed, you are paid back £2,345.00 over 7 years, tax free
3. This reduces your £4,500 investment to £2,155.00 with an estimated £990.00 of service costs over the life of the system.
The 2nd choice is our system sold and installed outside any of the governments interference and red tape, costing £2,000 installed including the choice of 2 flat plate panels, or evacuated tube heat pipe, with a choice of a solar powered DC or AC pump, all the parts to connect this kit into an excisting cylinder.
The SWH system kit through our selected group buyers/seller with years of experiance in this business is £1,000, with £800.00 for the installer team and 5% vat on completion

Can anybody reading this, tell me why anybody should take up the RHI through the green deal, when all they want is part of the hot water heating TAX FREE from the sun??

Thankyou for your time