Solar hotwater, controllers and panels.

[SteveBeck]

Am new to solar and have a few questions. About 20 years ago I bought a brushless hot water pump and ran it with a dc transformer through a wood burner going into a hot water tank. I needed no more than a handful of branches every day to heat a 40 gallon tank which would last me the day. It was real cheap(cut my electric bill by about 30%)! The pump came with a small PV panel but it wouldn't drive the pump on it's own(needed a battery and a controller which I never went down that road).

I now live in the city and want to turn towards solar using this pump which is rated 10 watts, 20 volts max(which I figured would take a 12v 5.5 amp battery) but I still want to stay away from a battery at the moment.

My question is, if I go with a larger PV panel(say a 100w panel, to begin with, producing enough current to run the pump without batteries), will I need to get a controller that matches this pump so that when the sun is out, the pump will run(without a battery, supplying enough current to run the pump but not burn it out) and where does any excess energy produced from the PV panel go until I start increasing my solar abilities? And if so, what controller might you suggest?

I want to start out installing panels and wiring the housing lights with DC (like in an RV) so that I use less and less electricity from the grid as I advance my system.

I understand that eventually I will need a battery bank but I want to start out as off-grid as possible at first and work my way up to a battery system that will be just necessary to run the larger appliances. Does this make sense or am I going about it all wrong here? I am limited on cash so I want to build and learn as I go and go the cheapest route possible.

Thanks in advance and sorry for not reading through thousands and thousands of previous posts to maybe find an already post to this nature but skimming through what I see doesn't tend to touch on such a precise nature as in what I am asking specifically...

 

[12VoltInstalls]

if I go with a larger PV panel(say a 100w panel, to begin with, producing enough current to run the pump without batteries

I know what your goal is. I would not buy a 100W panel at this stage- I would source a ‘leftover’ or newer used 300W panel and use a proper mppt controller. With a battery.
Then you can get more use out of it and not be dead on partly cloudy days.
Because:

Does this make sense or am I going about it all wrong here? I am limited on cash so I want to build and learn as I go and go the cheapest route possible.

The least costly over a few years’ service time will NOT be “the cheapest route possible.” Plus something that meets or exceeds expectations all of the time if not most of the time returns better value that translates to dollars.

will I need to get a controller that matches this pump so that when the sun is out, the pump will run(without a battery, supplying enough current to run the pump but not burn it out) and where does any excess energy produced from the PV panel go until I start increasing my solar abilities? And if so, what controller might you suggest?

I ‘think’ you could do this with an Epever charge controller. Using the ‘load’ outputs. It may not power up without a battery however- some form of battery is needed. You cannot simply feed panel voltage to the pump since most commodity 100W panels are ~22VOC though there are sun that max at 18VOC

learn as I go and go the cheapest route possible.

the cheapest route will cost more in the end

Instead of putting weight on “the cheapest” I’d suggest offering what you need/can do budget wise- $100, $250, $400
Then I or anyone else can make appropriate suggestions.