I have played an Energy/ Fire blaster since I got started and I love him, but if I could go back and do it again I wouldn't choose those sets in a million years!
Build Up, Aim then Nova takes out even level toons if its well slotted for accuracy pretty well, but the recharge time means you are never going to farm much xp that way. My best advice to you is get in a big team!
If you insist in soloing then make sure you have haste, that will help with bigger mobs. Using things like BU+Aim+Snipe to get a head start on the Boss, then working down to easier enemies, but they have to be small mobs due to your squishiness. You should be good at using Knockback to keep enemies off their feet at this stage so make sure and use that, if someone his hurting you in Melee Range then use Power Push followed by Ring of Fire to take him out of range and hold him while you deal with others first. Enemies that are hurting you at longer range you need to focus on until they are outta there.
Energy Torrent will buy you time if you are eating damage from a variety of foes, one slot it for knockback and you will take all affected off their feet, again if it is not a smallish mob the aggro of this will kill ya!
Hmmmm, well I do have Energy Manipulation or my secondary and never even tried Fire Manipulation, but my advice if you're going for the sologrind, you'll need to consider a few things. 6 slot your nova straight away, you cannot go wrong with 3 damage 3 recharge, no need to worry about accuracy apparently because the base accuracy rate of a nova is very high, and with aim you should hit pretty much everything. 1 other thing, [u]Aid Self.[u] Get it if you want to stay on your feet that extra bit longer. I have mine slotted as 2 Heal 2 Interrupt reduction 2 Recharge. If you had taken Energy Manipulation and had power boost, activate that and Aid Self, boom, straight away about 1/2 your hitpoints come back. But without power boost it should recover around 1/3. Also bear in mind it is an interruptable power so best thing to do is stay focused and time it right, or do a quick hop back out of harms way and activate aid self. Its very useful. If you are taking on the solo grind aswell, keep a tray full of insps to keep you going.
Another thing, force mastery as your epic powerset, if you want to solo later on, it's a smart move. Personal Force Field will act as an excellent panic button. A good combo if you just can't hold out any longer is PFF+Aid Self. whilst most attacks are flying off the force field you can whack out the lil device, heal yourself, shut off PFF and get back into the fray. Temp Invunerability and Force of Nature are a must too, combined they have some very very nice damage resistances. I wouldn't take Repulsion field personally, but you can do if you do not wish to have any enemies up close with you, but keep in mind every enemy that hits your RF will cost additional endurance; in a big mob that can mean and end crash, and if you're out of end insps and mez'd, oopsie 
So to recap, 6 slot nova and aid self, and Force Mastery later on. But In my opinion, just try teams ^^
Hope it helps and have fun,
Capt A
Yo!
So I'm a level 33 Energy/Fire blaster sologrinding in Bricks. A bad [censored] way to grind is to pop Aim and jump in a crowd and go Nova.
That's one way, but are there any other?
I can take out 1-2 (maybe 3) at the same time around my level without popping Insps, but are there any other secret way of sologrinding?
Cheers, Tox.