Heat Pump - I have hive installed which controls the heating and have hot water on schedule. I also have 4 TRV which control the bedroom temperatures i.e, stops heating the room when it reaches the desired temperature. What i have observed is that the heat coming out of the radiators when the flow is set at 45 is like lukewarm heat. When it is increased to 55 the radiators actually start to feel hot. Also, Heat Pump is running on compensation setting.

Hive and most other smart thermostats don't play well with heat pumps and should generally be disabled.. Radiators should be luke warm most of the time and never, or almost never, hot. 

I think it's highly likely that your settings are wrong and before concluding anything about the installation itself this needs to be fixed.  Heat pumps are run in trickle mode at low temperature 24x7 so that the energy supplied just matches the energy lost by the house, not on/off like boilers.  It's almost the polar opposite of how we run boilers in the UK, but results in cheaper operation and a more comfortable house.

It's difficult to adjust this outside the heating season but the basic procedure is

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Turn up all trvs to maximum

Turn up the hive and any other thermostats to maximum, set the heat pump and any external controls including the hive to run 24x7

Open any zone valves 24x7

Your house will get too warm.

Adjust the high oat end of the wc curve to say 27CFT at 20COAT

Slowly, over a period of several days, reduce the set ft at the low OAT end of the WC curve until the house is just the right temperature.   You need to be changing it a degree at a time only and leaving for 24hrs after each change (you may be able to go a bit faster at first).  It will take several days.

If different rooms settle at different temperatures (or you want some rooms, eg bedroom, a bit cooler) you may need to balance radiators, which you do by adjusting the locksield valve (the one opposite the trv)

Once the house is stable at the temperature you want you have the correct settings.  Leave all (or at least most) trvs on max and any external thermostats and the hive no less than 2C above the target temperature.  If one or two rooms experience solar gain or any other disturbance which causes the room periodically to overheat, you can use a trv, set a couple of degrees above target, as a limiter in that room.

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I can provide more detail and it would help to know the make of heat pump, but until you start heating again it's more or less impossible to do this adjustment.  Once it is done we will know whether the emitters have been correctly sized or not.

Solar Panels - I have a gable roof with is south facing, not sure of the exact angle, but during summers (when it is a sunny day with no clouds) sun will be directly on top most of the day facing into it and there is no restrictions.

This is a bit less obvious.  The most probable faults causing lower than expected output are:

• Panels dirty
• One or more panels not connected 
• Inverter fault

None of these are especially likely so again I think we first need to be certain there is a fault.  Gable ends can be quite shallow, or quite steep, so more info on this would help.  Also how many panels do you have, what is the rating of each panel, what make and model of inverter and how are you measuring the output power?  The certificate should have most of this info except for how you are measuring the output power.  Where roughly in Scotland are you (its lattitude that matters).

Sorry to ask more questions but its difficult to diagnose a fault without more detail.

Heat Pump: The heat calculations have not be done right per room and as the flow rate mentioned on the MCS certificate (45) is not achieving the desired heat output. Currently the flow rate is sitting at 55 which is the max it can go. What i need is to get the heat loss calculations done again to identify the right size of radiators for each room that will deliver the desired heat output at 45 flow rate. Don't think I am qualified enough to take this on myself. Do you have any suggestions

Are you operating the heat pump 24*7 with all, or almost all, trvs fully open, room thermostat if any set at least 2C above target and weather compensation adjusted accordingly (IE as low as you can get it consistent with just heating the house).  If not then it may be that all you need to do is tweak the controls. 

If you are already doing this can you provide some more info about heat pump, controls and calculations/observed issues?

Solar Panels: The MCS certificate says that i can get a heat output over 4KwH but in actual reality I have received ever anymore than 2.7Kwh. Not sure if there is anything that I can do to improve it.

Solar panels are specified by 'kWp' (kW peak) output which is the output when the sun is falling perpendicular to the panels.  Most installations come close to the peak but don't necessarily match it.  You imply you are in Scotland which typically will reduce output (unless you have a steep roof) simply because the sun is lower in the sky.  What angle (to the vertical) and orientation (compass angle) are your solar panels at?

Most likely your inverter is anyway specified at 3.68kW (IE 16A at 230V), the max allowed without express permission from your electric company.

I apologise if you have already considered these matters, but we need first to check it's not something relatively simple.

Heat Pump: The heat calculations have not be done right per room and as the flow rate mentioned on the MCS certificate (45) is not achieving the desired heat output. Currently the flow rate is sitting at 55 which is the max it can go. What i need is to get the heat loss calculations done again to identify the right size of radiators for each room that will deliver the desired heat output at 45 flow rate. Don't think I am qualified enough to take this on myself. Do you have any suggestions

Are you operating the heat pump 24*7 with all, or almost all, trvs fully open, room thermostat if any set at least 2C above target and weather compensation adjusted accordingly.  If not then it may be that all you need to do is tweak the controls. 

Solar Panels: The MCS certificate says that i can get a heat output over 4KwH but in actual reality I have received ever anymore than 2.7Kwh. Not sure if there is anything that I can do to improve it.

Solar panels are specified by 'kWp' (kW peak) output which is the output when the sun is falling perpendicular to the panels.  Most installations come close to the peak but don't necessarily match it.  You imply you are in Scotland which typically will reduce output (unless you have a steep roof) simply because the sun is lower in the sky.  What angle (to the vertical) and orientation (compass angle) are your solar panels at?

Most likely your inverter is anyway specified at 3.68kW (IE 16A at 230V), the max allowed without express permission from your electric company.

I apologise if you have already considered these matters, but we need first to check it's not something relatively simple.

I'm really sorry to hear about your experience which unfortunately, whilst relatively rare, is not unknown in the renewables industry, or indeed the construction industry more generally.  I am not the expert on routes to 'escalate' so will leave it to others to comment on this.

My personal experience in such cases (having been there myself with other parts of the construction industry), is that self help can become the only practical option, at least  sometimes.   If you do want to explore options to improve your systems without the help of your installer please feel free to post some details and I or others here may well have some suggestions.  I appreciate you may not be ready to take this step yet, so equally please don't feel you have to.  Many problems with heat pumps in particular come down to fairly simple controller configuration issues which the householder can in reality sort out.

If you’re up for it, I’d really encourage you to turn this experience into an open letter (I’d be happy to publish it on the main RHH site if that helps amplify your plight) and I will send that link to all the major stakeholders at MCS (including Ian Rippon) for comment. The more we can expose the disconnect between government rhetoric (ie. "use an MCS-certified installer for peace of mind!") and the reality on the ground, the more pressure we can collectively put on those in charge to tighten the system.