VS pump vs. Dual Speed vs. keeping Status Quo

[mas985]

A variable speed pump will nearly always be more cost effective over the life of the pump. Yes it costs more up front but it will save more on electrical costs even if you run it at higher speeds for part of the cycle (I do this on my two speed). In my signature below is a link to "Pump Modeling Tools" which contains a spreadsheet that I put together which will compare the lifetime costs of any pumps that are in the CEC database. But without doing the analysis, I can tell you that the VS pumps will usually come out ahead but it depends on what you pay for electricity and if you will also need a controller.

As for your questions:

#1 - Yes, you will need to run the pump at higher speed for solar if you have an elevated installation AND you have a vacuum release valve near the top of the panels. You can lower the VRV and make solar work at lower pressure and flow rates but then the efficiency of the panels will suffer. But still, a VS pump will allow you to tune the flow rate to be just enough to keep the VRV closed and the panel efficiency up.

#2 - Yes but so what? You are saving money. If you want to impress vistors, just up the RPM of the pump for the party.

[chem geek]

I have a solar system, yet I was able to cut my pump electricity costs IN HALF from around $1400 to $700 per year (at high marginal 40 cents per kilowatt-hour rates) when I switched from a 1 HP (1.65 SF) Jandy HHP pump and a 3/4 HP booster pump (for the Letro Legend pool sweep) to an IntelliFlo VF pump. Most of the savings comes from the fact that even when I'm using solar, it isn't on for all 8 hours of pump run time. It's only on for 4-6 hours so the other 2-4 hours I'm able to run at a lower 26 GPM, 1500 RPM, 275 Watts. Even when the solar is on, I can run at 48 GPM (4 GPM per panel for 12 panels), 3000 RPM, 1500 Watts with greater efficiency than my old pump which was running at around 55 GPM (maybe 1800 Watts) or so when the solar was on (and 80 GPM or so when the solar was off, still close to 1800 Watts). The rest of the savings was using the IntelliFlo to power The Pool Cleaner at 15 GPM, 2200 RPM, 540 Watts through its dedicated line compared to the 3/4 HP booster pump at around 1400 Watts.

Richard